Santu Baidya

@juit.ac.in

Assistant Professor and Department of Physics and Materials Science
Jaypee University of Information Technology



              

https://researchid.co/santubaidya

EDUCATION

Doctor of Philosophy ( from Calcutta Unversity

RESEARCH, TEACHING, or OTHER INTERESTS

Condensed Matter Physics, Materials Science, Mechanics of Materials, Surfaces, Coatings and Films

26

Scopus Publications

663

Scholar Citations

15

Scholar h-index

20

Scholar i10-index

Scopus Publications

  • Stripe helical magnetism and two regimes of anomalous Hall effect in NdAlGe
    Hung-Yu Yang, Jonathan Gaudet, Rahul Verma, Santu Baidya, Faranak Bahrami, Xiaohan Yao, Cheng-Yi Huang, Lisa DeBeer-Schmitt, Adam A. Aczel, Guangyong Xu,et al.
    American Physical Society (APS)
    We report the magnetic and electronic transport properties of the inversion and time-reversal symmetry breaking Weyl semimetal NdAlGe. This material is analogous to NdAlSi, whose helical magnetism presents a rare example of a Weyl-mediated collective phenomenon, but with a larger spin-orbit coupling. Our neutron diffraction experiments revealed that NdAlGe, similar to NdAlSi, supports an incommensurate Ising spin density wave ($T_{\\text{inc}}=6.8$ K) with a small helical spin canting of 3$^\\circ$ and a long-wavelength of $\\sim$ 35 nm, which transitions to a commensurate ferrimagnetic state below $T_{\\text{com}}=5.1$ K. Using small-angle neutron scattering, we showed that the zero-field cooled ferrimagnetic domains form stripes in real space with characteristic length scales of 18 nm and 72 nm parallel and perpendicular to the [110] direction, respectively. Interestingly, for the transport properties, NdAlSi does not exhibit an anomalous Hall effect (AHE) that is commonly observed in magnetic Weyl semimetals. In contrast to NdAlSi, we identify two different AHE regimes in NdAlGe that are respectively governed by intrinsic Berry curvature and extrinsic disorders/spin fluctuations. Our study suggests that Weyl-mediated magnetism prevails in this group of noncentrosymmetric magnetic Weyl semimetals NdAl$X$, but transport properties including AHE are affected by material-specific extrinsic effects such as disorders, despite the presence of prominent Berry curvature.

  • Magnetism and unconventional topology in LaCoO<inf>3</inf>/SrIrO<inf>3</inf>heterostructure
    Samir Rom, Santu Baidya, Subhro Bhattacharjee, and Tanusri Saha-Dasgupta
    AIP Publishing
    Employing first-principles calculations, we provide microscopic insights on the curious magnetic and topological properties of LaCoO3/SrIrO3 heterostructure, which has been recently synthesized [Kumar Jaiswal et al., Adv. Mater. 34, 2109163 (2022)]. Our computational study unravels transfer of polar charge from SrIrO3 to LaCoO3, thereby reducing the Co valence from 3+ toward 2+, supporting the experimental findings. Our study further reveals the stabilization of the intermediate spin state of Co and strong ferromagnetic Co–Co coupling in the LaCoO3 block of the heterostructure. This, in turn, is found to induce ferromagnetism in the pseudo-tetragonally structured SrIrO3 in the heterostructure geometry, providing an understanding of the origin of magnetism, which is counter-intuitive as both LaCoO3 and SrIrO3 are nonmagnetic in bulk form. Most interestingly, the band structure of ferromagnetic, tetragonal structured SrIrO3 is found to exhibit unconventional topology, manifested as C = 2 double Weyl points, which leads to the observed anomalous Hall effect. Our finding of C  =  2 double Weyl points, belonging to the class of charge-2 Dirac points, opens up the possibility of material realization of unconventional topological properties beyond the conventional Dirac and C  =  1 Weyl points, which calls for future experiments.

  • Spin Hall angle of rhodium and its effects on magnetic damping of Ni<inf>80</inf>Fe<inf>20</inf> in Rh/Ni<inf>80</inf>Fe<inf>20</inf> bilayer
    Bipul Kr. Mahato, R. Medwal, S. Baidya, D. Kumar, S.N. Piramanayagam, and R.S. Rawat
    Elsevier BV

  • Phonon spectrum of Pr2Zr2 O7 and Pr2Ir2 O7 as evidence of coupling of the lattice with electronic and magnetic degrees of freedom
    Yuanyuan Xu, Huiyuan Man, Nan Tang, Takumi Ohtsuki, Santu Baidya, Satoru Nakatsuji, David Vanderbilt, and Natalia Drichko
    American Physical Society (APS)
    Yuanyuan Xu, Huiyuan Man, 2 Nan Tang, Takumi Ohtsuki, 2 Santu Baidya, Hongbin Zhang, Satoru Nakatsuji, 4, 5, 6, 7 David Vanderbilt, and Natalia Drichko Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan Department of Physics and Astronomy, Rutgers University CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan

  • Weyl-mediated helical magnetism in NdAlSi
    Jonathan Gaudet, Hung-Yu Yang, Santu Baidya, Baozhu Lu, Guangyong Xu, Yang Zhao, Jose A. Rodriguez-Rivera, Christina M. Hoffmann, David E. Graf, Darius H. Torchinsky,et al.
    Springer Science and Business Media LLC

  • Importance of dynamic lattice effects for crystal field excitations in the quantum spin ice candidate Pr2Zr2 O7
    Yuanyuan Xu, Huiyuan Man, Nan Tang, Santu Baidya, Hongbing Zhang, Satoru Nakatsuji, David Vanderbilt, and Natalia Drichko
    American Physical Society (APS)
    Yuanyuan Xu, Huiyuan Man, 2 Nan Tang, 2 Santu Baidya, Honbin Zhang, Satoru Nakatsuji, 4, 5, 6, 7 David Vanderbilt, and Natalia Drichko Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba 277-8581, Japan Department of Physics and Astronomy, Rutgers University CREST, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan Institute for Quantum Matter and Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA Department of Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan Trans-scale Quantum Science Institute, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan (Dated: July 28, 2021)

  • First-principles theory of the Dirac semimetal Cd3As2 under Zeeman magnetic field
    Santu Baidya and David Vanderbilt
    American Physical Society (APS)
    Time-reversal broken Weyl semimetals have attracted much attention recently, but certain aspects of their behavior, including the evolution of their Fermi surface topology and anomalous Hall conductivity with Fermi-level position, have remained underexplored. A promising route to obtain such materials may be to start with a nonmagnetic Dirac semimetal and break time-reversal symmetry via magnetic doping or magnetic proximity. Here we explore this scenario in the case of the Dirac semimetal ${\\mathrm{Cd}}_{3}{\\mathrm{As}}_{2}$ based on first-principles density-functional calculations and subsequent low-energy modeling of ${\\mathrm{Cd}}_{3}{\\mathrm{As}}_{2}$ in the presence of a Zeeman field applied along the symmetry axis. We clarify how each fourfold degenerate Dirac node splits into four Weyl nodes, two with chirality $\\ifmmode\\pm\\else\\textpm\\fi{}1$ and two higher-order nodes with chirality $\\ifmmode\\pm\\else\\textpm\\fi{}2$. Using a minimal $k\\ifmmode\\cdot\\else\\textperiodcentered\\fi{}p$ model Hamiltonian whose parameters are fit to the first-principles calculations, we detail the evolution of the Fermi surfaces and their Chern numbers as the Fermi energy is scanned across the region of the Weyl nodes at fixed Zeeman field. We also compute the intrinsic anomalous Hall conductivity as a function of the Fermi-level position, finding a characteristic inverted-dome structure. ${\\mathrm{Cd}}_{3}{\\mathrm{As}}_{2}$ is especially well suited to such a study because of its high mobility, but the qualitative behavior revealed here should be applicable to other Dirac semimetals as well.

  • Interplay of Magnetism and Topological Superconductivity in Bilayer Kagome Metals
    Santu Baidya, Aabhaas Vineet Mallik, Subhro Bhattacharjee, and Tanusri Saha-Dasgupta
    American Physical Society (APS)
    The binary intermetallic materials, M_{3}Sn_{2} (M=3d transition metal) present a new class of strongly correlated systems that naturally allows for the interplay of magnetism and metallicity. Using first principles calculations we confirm that bulk Fe_{3}Sn_{2} is a ferromagnetic metal, and show that M=Ni and Cu are paramagnetic metals with nontrivial band structures. Focusing on Fe_{3}Sn_{2} to understand the effect of enhanced correlations in an experimentally relevant atomistically thin single kagome bilayer, our ab initio results show that dimensional confinement naturally exposes the flatness of band structure associated with the bilayer kagome geometry in a resultant ferromagnetic Chern metal. We use a multistage minimal modeling of the magnetic bands progressively closer to the Fermi energy. This effectively captures the physics of the Chern metal with a nonzero anomalous Hall response over a material relevant parameter regime along with a possible superconducting instability of the spin-polarized band resulting in a topological superconductor.

  • Chern insulator with a nearly flat band in the metal-organic-framework-based Kagome lattice
    Santu Baidya, Seungjin Kang, Choong H. Kim, and Jaejun Yu
    Springer Science and Business Media LLC
    AbstractBased on first-principles density-functional theory (DFT) calculations, we report that the transition-metal bis-dithiolene, M3C12S12 (M = Mn and Fe), complexes can be a two-dimensional (2D) ferromagnetic insulator with nontrivial Chern number. Among various synthetic pathways leading to metal bis-dithiolenes, the simplest choice of ligand, Benzene-hexathiol, connecting metal cations to form a Kagome lattice is studied following the experimental report of time-reversal symmetric isostructural compound Ni3C12S12. We show sulfur and carbon-based ligands play the key role in making the complexes topologically nontrivial. An unusual topological quantum phase transition induced by the on-site Coulomb interaction brings a nearly flat band with a nonzero Chern number as the highest occupied band. With this analysis we explain the electronic structure of the class M3C12S12 and predict the existence of nearly flat band with nonzero Chern number and it can be a fractional Chern insulator candidate with carrier doping.

  • Theoretical evidence of spin-orbital-entangled Jeff= 12 state in the 3d transition metal oxide CuAl2 O4
    Choong H. Kim, Santu Baidya, Hwanbeom Cho, Vladimir V. Gapontsev, Sergey V. Streltsov, Daniel I. Khomskii, Je-Geun Park, Ara Go, and Hosub Jin
    American Physical Society (APS)
    Transition metal oxides exhibit various competing phases and exotic phenomena depending on how their reaction to the rich degeneracy of the $d$-orbital. Large spin-orbit coupling (SOC) reduces this degeneracy in a unique way by providing a spin-orbital-entangled ground state for 4$d$ and 5$d$ transition metal compounds. In particular, the spin-orbital-entangled Kramers doublet, known as the $J_{\\mathbf{eff}}$=1/2 pseudospin, appears in layered iridates and $\\alpha$-RuCl$_3$, manifesting a relativistic Mott insulating phase. Such entanglement, however, seems barely attainable in 3$d$ transition metal oxides, where the SOC is small and the orbital angular momentum is easily quenched. From experimental and theoretical evidence, here we report on the CuAl$_2$O$_4$ spinel as the first example of a $J_{\\mathbf{eff}}$=1/2 Mott insulator in 3$d$ transition metal compounds. Based on the experimental study, including synthesis of the cubic CuAl$_2$O$_4$ single crystal, density functional theory and dynamical mean field theory calculations reveal that the $J_{\\mathbf{eff}}$=1/2 state survives the competition with an orbital-momentum-quenched $S$=1/2 state. The electron-addition spectra probing unoccupied states are well described by the $j_{\\mathbf{eff}}$=1/2 hole state, whereas electron-removal spectra have a rich multiplet structure. The fully relativistic entity found in CuAl$_2$O$_4$ provides new insight into the untapped regime where the spin-orbital-entangled Kramers pair coexists with strong electron correlation.

  • Tunable magnetic topological insulating phases in monolayer CrI3
    Santu Baidya, Jaejun Yu, and Choong H. Kim
    American Physical Society (APS)
    Tunable magnetic topological insulating phases in monolayer CrI3 Santu Baidya,1,2,* Jaejun Yu,3,† and Choong H. Kim1,2,‡ 1Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea 2Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea 3Center for Theoretical Physics, Department of Physics and Astronomy, Seoul National University, Seoul 08826, Republic of Korea

  • Confinement-driven electronic and topological phases in corundum-derived 3d -oxide honeycomb lattices
    Okan Köksal, Santu Baidya, and Rossitza Pentcheva
    American Physical Society (APS)
    Using density functional theory calculations including an on-site Coulomb term, we explore electronic and possibly topologically nontrivial phases in $3d$ transition metal oxide honeycomb layers confined in the corundum structure ($\\alpha$-Al$_2$O$_3$) along the [0001] direction. In most cases the ground state is a trivial antiferromagnetic Mott insulator, often with distinct orbital or spin states compared to the bulk phases. With imposed symmetry of the two sublattices the ferromagnetic phases of Ti, Mn, Co and Ni exhibit a characteristic set of four bands, two relatively flat and two with a Dirac crossing at K, associated with the single electron occupation of $e_{g}'$ (Ti) or $e_{g}$ (Mn, Co, Ni) orbitals. Our results indicate that the Dirac point can be tuned to the Fermi level using strain. Applying spin-orbit coupling (SOC) leads to a substantial anomalous Hall conductivity with values up to 0.94 $e^2/h$. Moreover, at $a_{Al_2O_3}$=4.81\\AA\\ we identify a particularly strong effect of SOC with out-of-plane easy axis for ($Ti_2$O$_3$)$_1$/(Al$_2$O$_3$)$_5$(0001) which stabilizes dynamically the system. Due to the unusually high orbital moment of -0.88$\\mu_{\\rm B}$ that nearly compensates the spin moment of 1.01$\\mu_{\\rm B}$, this system emerges as a candidate for the realization of the topological Haldane model of spinless fermions. Parallels to the perovskite analogs (La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$(111) are discussed.

  • High-temperature large-gap quantum anomalous Hall insulating state in ultrathin double perovskite films
    Santu Baidya, Umesh V. Waghmare, Arun Paramekanti, and Tanusri Saha-Dasgupta
    American Physical Society (APS)
    Towards the goal of realizing topological phases in thin films of correlated oxide and heterostructures, we propose here a quantum anomalous Hall insulator (QAHI) in ultrathin films of double perovskites based on mixed $3d\\ensuremath{-}5d$ or $3d\\ensuremath{-}4d$ transition-metal ions, grown along the [111] direction. Considering the specific case of ultrathin ${\\mathrm{Ba}}_{2}{\\mathrm{FeReO}}_{6}$, we present a theoretical analysis of an effective Hamiltonian derived from first principles. We establish that a strong spin-orbit coupling at the Re site, ${t}_{2g}$ symmetry of the low-energy $d$ bands, polarity of its [111] orientation of perovskite structure, and mixed $3d\\ensuremath{-}5d$ chemistry results in room temperature magnetism with a robust QAHI state of Chern number $C=1$ and a large band gap. We uncover and highlight a nonrelativistic orbital Rashba-type effect in addition to the spin-orbit coupling, that governs this QAHI state. With a band gap of $\\ensuremath{\\sim}100$ meV in electronic structure and magnetic transition temperature ${T}_{c}\\ensuremath{\\sim}300\\phantom{\\rule{0.28em}{0ex}}\\mathrm{K}$ estimated by Monte Carlo simulations, our finding of the QAHI state in ultrathin ${\\mathrm{Ba}}_{2}{\\mathrm{FeReO}}_{6}$ is expected to stimulate experimental verification along with possible practical applications of its dissipationless edge currents.

  • Configuration and self-averaging in disordered systems
    S. Chowdhury, D. Jana, B. Sadhukhan, D. Nafday, S. Baidya, T. Saha-Dasgupta, and A. Mookerjee
    Springer Science and Business Media LLC

  • Design of Chern and Mott insulators in buckled 3d oxide honeycomb lattices
    David Doennig, Santu Baidya, Warren E. Pickett, and Rossitza Pentcheva
    American Physical Society (APS)
    Perovskite bilayers with (111)-orientation combine a honeycomb lattice as a key feature with the strongly correlated, multiorbital nature of electrons in transition metal oxides. In a systematic DFT+$U$ study of (111)-oriented (La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, we establish trends in the evolution of ground states versus band filling in (111)-oriented (La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, with $X$ spanning the entire $3d$ transition metal series. The competition between local quasi-cubic and global triangular symmetry triggers unanticipated broken symmetry phases, with mechanisms ranging from Jahn-Teller distortions, to charge-, spin-, and orbital-ordering. LaMnO$_3$, where spin-orbit coupling opens a sizable gap in the Dirac-point Fermi surface, emerges as a topological Chern insulator.

  • Controlled confinement of half-metallic two-dimensional electron gas in BaTiO3/Ba2FeReO6/BaTiO3 heterostructures: A first-principles study
    Santu Baidya, Umesh V. Waghmare, Arun Paramekanti, and Tanusri Saha-Dasgupta
    American Physical Society (APS)
    Using density functional theory calculations, we establish that the half-metallicity of bulk Ba2FeReO6 survives down to 1 nm thickness in BaTiO3/Ba2FeReO6/BaTiO3 heterostructures grown along the (001) and (111) directions. The confinement of the two-dimensional (2D) electron gas in this quantum well structure arises from the suppressed hybridization between Re/Fe d states and unoccupied Ti d states, and it is further strengthened by polar fields for the (111) direction. This mechanism, distinct from the polar catastrophe, leads to an order of magnitude stronger confinement of the 2D electron gas than that at the LaAlO3/SrTiO3 interface. We further show low-energy bands of (111) heterostructure display nontrivial topological character. Our work opens up the possibility of realizing ultrathin spintronic devices.

  • Breakdown of J=0 nonmagnetic state in d4 iridate double perovskites: A first-principles study
    Sayantika Bhowal, Santu Baidya, Indra Dasgupta, and Tanusri Saha-Dasgupta
    American Physical Society (APS)
    Through first-principles calculations, we study the electronic structure of double-perovskite iridates with Ir in the ${d}^{4}$ valence state. Contrary to the expected strong spin-orbit driven $J=0$ nonmagnetic state, we find finite moment at the Ir site, exhibiting breakdown of the $J=0$ state. We further find the band structure effect rather than the crystal field effect to be responsible for this breakdown. The antiferromagnetic superexchange interaction between Ir moments, in general, makes these compounds insulating.


  • Covalency-driven structural instability and spin-phonon coupling in barium cobalt oxychloride
    Tanushree Chakraborty, S. Baidya, Carlo Meneghini, Tanusri Saha-Dasgupta, Giulia Veronesi, Marco Merlini, Hiroko Yokota, Mitsuru Itoh, S. Majumdar, and Sugata Ray
    American Physical Society (APS)
    Tanushree Chakraborty,1 S. Baidya,2 Carlo Meneghini,3,* Tanusri Saha-Dasgupta,2,† Giulia Veronesi,4 Marco Merlini,5 Hiroko Yokota,6 Mitsuru Itoh,7 S. Majumdar,8 and Sugata Ray1,9,‡ 1Centre for Advanced Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India 2Department of Condensed Matter and Materials Science, S. N. Bose National Centre for Basic Sciences, JD Block, Sector III, Salt Lake, Kolkata 700098, India 3Dipartimento di Scienze, Universita Roma Tre, Via della Vasca Navale, 84 I-00146 Roma, Italy 4European Synchrotron Radiation Facility, POB 220, Grenoble Cedex 9, France 5Universita di Milano–Dip. di Scienze della Terra Ardito Desio, Milano, Italy 6Department of Physics, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan 7Materials and Structures Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Yokohama 226-8503, Japan 8Solid State Physics, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India 9Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032, India (Received 2 July 2014; revised manuscript received 1 December 2014; published 29 December 2014)

  • A real-space study of random extended defects in solids: Application to disordered Stone-Wales defects in graphene
    Suman Chowdhury, Santu Baidya, Dhani Nafday, Soumyajyoti Halder, Mukul Kabir, Biplab Sanyal, Tanusri Saha-Dasgupta, Debnarayan Jana, and Abhijit Mookerjee
    Elsevier BV

  • Crystal structure and magnetic properties of a new layered sodium nickel hydroxide phosphate, Na<inf>2</inf>Ni<inf>3</inf>(OH)<inf>2</inf>(PO <inf>4</inf>)<inf>2</inf>
    Olga Yakubovich, Galina Kiriukhina, Olga Dimitrova, Anatoly Volkov, Alexey Golovanov, Olga Volkova, Elena Zvereva, Santu Baidya, Tanusri Saha-Dasgupta, and Alexander Vasiliev
    Royal Society of Chemistry (RSC)
    Mixed sodium nickel hydroxide phosphate, Na2Ni3(OH)2(PO4)2, has been synthesized hydrothermally from the system NiCO3-Na4P2O7-NaCl-H2O. Its monoclinic crystal structure has been determined by single crystal X-ray diffraction: a = 14.259(5), b = 5.695(2), c = 4.933(1) Å, β = 104.28(3)°, space group C2/m, Z = 2, ρc = 3.816 g cm(-3), R = 0.026. The underlying spin model has been characterized in terms of first-principles electronic structure calculations. The compound is formed by alternating layers of [NiO6] octahedra and [NaO7] polyhedra, combined in the [100] direction with tetrahedral [PO4] oxocomplexes and hydrogen bonds. The novel phase is treated as an isostructural variant of the two-dimensional potassium manganese hydroxide vanadate, K2Mn3(OH)2(VO4)2, which can be formally obtained by morphotropic substitutions of all positions in the cationic sublattice. The stripe arrangement of Ni(2+) ions (S = 1) within [NiO4(OH)2] layers of Na2Ni3(OH)2(PO4)2 is unique in the sense that its magnetic topology places it in between widely discussed honeycomb and kagomé lattices. The Na2Ni3(OH)2(PO4)2 is a low-dimensional magnet, which reaches the short-range correlation regime at Tmax = 38.4 K and orders antiferromagnetically at TN = 33.4 K.

  • Copper rubidium diphosphate, Rb<inf>2</inf>Cu<inf>3</inf>(P <inf>2</inf>O<inf>7</inf>)<inf>2</inf>: Synthesis, crystal structure, thermodynamic and resonant properties
    Larisa Shvanskaya, Olga Yakubovich, Anna Ivanova, Santu Baidya, Tanusri Saha-Dasgupta, Elena Zvereva, Alexey Golovanov, Olga Volkova, and Alexander Vasiliev
    Royal Society of Chemistry (RSC)
    A new compound, Rb2Cu3(P2O7)2, has been obtained from the melt in the Rb–Cu–P–O system. Its monoclinic crystal structure was determined by single-crystal X-ray diffraction: space group P21/c, Z = 2, a = 7.7119(8) A, b = 10.5245(9) A, c = 7.8034(9) A, β = 103.862(5)° at 293 K, R = 0.030. The copper ions show coordination number (CN) 6 (4+2, distorted tetragonal bipyramidal). Trimers of [CuO6] polyhedra sharing cis-edges form together with diphosphate groups of two tetrahedra [P2O7] a microporous 3D framework with channels open along the c direction. The rubidium ions positioned in the channels show CN 10. The new phase is isotypic to Cs2Cu3(P2O7)2. The regular changes in cell dimensions in the row Cs2Cu3(P2O7)2 → Rb2Cu3(P2O7)2 are caused by the compression of channel volumes due to decrease of the Cu–O–P angles in the framework windows. An electron spin resonance study indicates appearance of short range magnetic correlations below ∼120 K, long range magnetic order takes place at TN = 9.2 K as follows from magnetization and specific heat measurements. First principles calculations of the magnetic exchanges indicate that the effective Cu–Cu hopping interactions corresponding to super–super-exchange paths involving P atoms are much stronger than those within the edge-sharing Cu2–Cu1–Cu2 trimer units.

  • Interplay of localized and itinerant character of Ru ions: Tl <inf>2</inf>Ru <inf>2</inf>O <inf>7</inf> versus Hg <inf>2</inf>Ru <inf>2</inf>O <inf>7</inf>
    Santu Baidya, Soumyajit Sarkar, T. Saha-Dasgupta, and D. D. Sarma
    American Physical Society (APS)
    We carry out a comparative study of the electronic structure of two pyrochlore ruthenate compounds, Tl2Ru2O7 and Hg2Ru2O7, in terms of first principles calculations. Our study reveals the Ru d electrons in Hg2Ru2O7 to be much more delocalized compared to that in Tl2Ru2O7. The subtle change in the Ru-d bandwidths in the two compounds, triggered by the differences in Hg 5d-Ru 4d hybridization compared to that of Tl 5d-Ru 4d, bring in the observed differences in behavior. Our study further shows that the development of long range noncollinear antiferromagnetic structure at low temperature is sufficient to produce the insulating solution in Hg2Ru2O7, in line with the prediction from recent nuclear magnetic resonance study.

  • Effect of A cation on magnetic properties of double perovskite compounds: From ferromagnetic Ca <inf>2</inf>CrSbO <inf>6</inf> to antiferromagnetic Sr <inf>2</inf>CrSbO <inf>6</inf>
    Santu Baidya and T. Saha-Dasgupta
    American Physical Society (APS)
    Using first-principles, density functional theory based calculations, we explore the microscopic origin of the switching from antiferromagnetic to ferromagnetic behavior, in replacing Sr by Ca in Sr2CrSbO6 double perovskite. Our study reveals that the difference in the strength of covalency between Sr and Cr compared to that between Ca and Cr, added to the structural differences, dictates the sign of the dominant first nearest-neighbor Cr-Cr interaction, and thereby, is the responsible factor for this interesting behavior. The antiferromagnetically coupledCr spins in frustrated face-centered cubic lattice of Sr2CrSbO6 double perovskite structure shows ordering in A-type antiferromagnetic structure, driven by the magnetocrystalline anisotropy.

  • Understanding neutron scattering data in YMn<inf>2</inf>O<inf>5</inf>: An effective spin Hamiltonian
    Santu Baidya, Prabuddha Sanyal, Hena Das, Bertrand Roessli, Tapan Chatterji, and T. Saha-Dasgupta
    American Physical Society (APS)
    We construct an effective spin Hamiltonian for YMn 2 O 5 through analysis of first-principles density-functional theory results. Using our first-principles-derived spin Hamiltonian we calculate the magnon dispersion of this compound and compare with the experimentally measured spectra probed using inelastic neutron scattering. Our first-principles-derived set of magnetic interaction parameters show the importance of the Mn1-Mn2 interaction along the b axis, which was ignored in the literature. We provide justification in favor of our first-principles-derived parameters.

RECENT SCHOLAR PUBLICATIONS

  • A large anomalous Hall effect and Weyl nodes in bulk FeNi: a density functional theory study
    S Thakur, S Baidya
    arXiv preprint arXiv:2501.11025 2025

  • Stripe helical magnetism and two regimes of anomalous Hall effect in NdAlGe
    HY Yang, J Gaudet, R Verma, S Baidya, F Bahrami, X Yao, CY Huang, ...
    Physical Review Materials 7 (3), 034202 2023

  • Magnetism and unconventional topology in LaCoO3/SrIrO3 heterostructure
    S Rom, S Baidya, S Bhattacharjee, T Saha-Dasgupta
    Applied Physics Letters 122 (2) 2023

  • Spin Hall angle of rhodium and its effects on magnetic damping of Ni80Fe20 in Rh/Ni80Fe20 bilayer
    BK Mahato, R Medwal, S Baidya, D Kumar, SN Piramanayagam, ...
    Journal of Magnetism and Magnetic Materials 555, 169404 2022

  • Phonon spectrum of and as evidence of coupling of the lattice with electronic and magnetic degrees of freedom
    Y Xu, H Man, N Tang, T Ohtsuki, S Baidya, S Nakatsuji, D Vanderbilt, ...
    Physical Review B 105 (7), 075137 2022

  • Weyl-mediated helical magnetism in NdAlSi
    J Gaudet, HY Yang, S Baidya, B Lu, G Xu, Y Zhao, JA Rodriguez-Rivera, ...
    Nature materials 20 (12), 1650-1656 2021

  • Importance of dynamic lattice effects for crystal field excitations in the quantum spin ice candidate
    Y Xu, H Man, N Tang, S Baidya, H Zhang, S Nakatsuji, D Vanderbilt, ...
    Physical Review B 104 (7), 075125 2021

  • First-principles theory of the Dirac semimetal under Zeeman magnetic field
    S Baidya, D Vanderbilt
    Physical Review B 102 (16), 165115 2020

  • Interplay of Magnetism and Topological Superconductivity in Bilayer Kagome Metals
    S Baidya, AV Mallik, S Bhattacharjee, T Saha-Dasgupta
    Phys. Rev. Lett. 125, 026401 (2020) 2020

  • Theoretical evidence of spin-orbital-entangled state in the transition metal oxide
    CH Kim, S Baidya, H Cho, VV Gapontsev, SV Streltsov, DI Khomskii, ...
    Physical Review B 100 (16), 161104 2019

  • Chern insulator with a nearly flat band in the metal-organic-framework-based kagome lattice
    S Baidya, S Kang, CH Kim, J Yu
    Scientific reports 9 (1), 13807 2019

  • Tunable magnetic topological insulating phases in monolayer
    S Baidya, J Yu, CH Kim
    Physical Review B 98 (15), 155148 2018

  • Confinement-driven electronic and topological phases in corundum-derived -oxide honeycomb lattices
    O Kksal, S Baidya, R Pentcheva
    Physical Review B 97 (3), 035126 2018

  • High-temperature large-gap quantum anomalous Hall insulating state in ultrathin double perovskite films
    S Baidya, UV Waghmare, A Paramekanti, T Saha-Dasgupta
    Physical Review B 94 (15), 155405 2016

  • Configuration and self-averaging in disordered systems
    S Chowdhury, D Jana, B Sadhukhan, D Nafday, S Baidya, ...
    Indian Journal of Physics 90, 649-657 2016

  • Design of Chern and Mott insulators in buckled oxide honeycomb lattices
    D Doennig, S Baidya, WE Pickett, R Pentcheva
    Physical Review B 93 (16), 165145 2016

  • Controlled confinement of half-metallic two-dimensional electron gas in heterostructures: A first-principles study
    S Baidya, UV Waghmare, A Paramekanti, T Saha-Dasgupta
    Physical Review B 92 (16), 161106 2015

  • Breakdown of nonmagnetic state in iridate double perovskites: A first-principles study
    S Bhowal, S Baidya, I Dasgupta, T Saha-Dasgupta
    Physical Review B 92 (12), 121113 2015

  • Covalency driven low-temperature structural distortion and its effect on electronic structure of
    S Baidya, T Saha-Dasgupta
    Physical Review B 91 (7), 075123 2015

  • Covalency-driven structural instability and spin-phonon coupling in barium cobalt oxychloride
    T Chakraborty, S Baidya, C Meneghini, T Saha-Dasgupta, G Veronesi, ...
    Physical Review B 90 (23), 235147 2014

MOST CITED SCHOLAR PUBLICATIONS

  • Weyl-mediated helical magnetism in NdAlSi
    J Gaudet, HY Yang, S Baidya, B Lu, G Xu, Y Zhao, JA Rodriguez-Rivera, ...
    Nature materials 20 (12), 1650-1656 2021
    Citations: 94

  • Electronic structure and phonons in LaCoMnO: A ferromagnetic insulator driven by Coulomb-assisted spin-orbit coupling
    S Baidya, T Saha-Dasgupta
    Physical Review B—Condensed Matter and Materials Physics 84 (3), 035131 2011
    Citations: 89

  • Breakdown of nonmagnetic state in iridate double perovskites: A first-principles study
    S Bhowal, S Baidya, I Dasgupta, T Saha-Dasgupta
    Physical Review B 92 (12), 121113 2015
    Citations: 76

  • Tunable magnetic topological insulating phases in monolayer
    S Baidya, J Yu, CH Kim
    Physical Review B 98 (15), 155148 2018
    Citations: 45

  • Design of Chern and Mott insulators in buckled oxide honeycomb lattices
    D Doennig, S Baidya, WE Pickett, R Pentcheva
    Physical Review B 93 (16), 165145 2016
    Citations: 43

  • A real-space study of random extended defects in solids: Application to disordered Stone–Wales defects in graphene
    S Chowdhury, S Baidya, D Nafday, S Halder, M Kabir, B Sanyal, ...
    Physica E: Low-dimensional Systems and Nanostructures 61, 191-197 2014
    Citations: 32

  • Chern insulator with a nearly flat band in the metal-organic-framework-based kagome lattice
    S Baidya, S Kang, CH Kim, J Yu
    Scientific reports 9 (1), 13807 2019
    Citations: 27

  • First-principles theory of the Dirac semimetal under Zeeman magnetic field
    S Baidya, D Vanderbilt
    Physical Review B 102 (16), 165115 2020
    Citations: 25

  • High-temperature large-gap quantum anomalous Hall insulating state in ultrathin double perovskite films
    S Baidya, UV Waghmare, A Paramekanti, T Saha-Dasgupta
    Physical Review B 94 (15), 155405 2016
    Citations: 23

  • Importance of dynamic lattice effects for crystal field excitations in the quantum spin ice candidate
    Y Xu, H Man, N Tang, S Baidya, H Zhang, S Nakatsuji, D Vanderbilt, ...
    Physical Review B 104 (7), 075125 2021
    Citations: 21

  • Interplay of Magnetism and Topological Superconductivity in Bilayer Kagome Metals
    S Baidya, AV Mallik, S Bhattacharjee, T Saha-Dasgupta
    Phys. Rev. Lett. 125, 026401 (2020) 2020
    Citations: 21

  • Stripe helical magnetism and two regimes of anomalous Hall effect in NdAlGe
    HY Yang, J Gaudet, R Verma, S Baidya, F Bahrami, X Yao, CY Huang, ...
    Physical Review Materials 7 (3), 034202 2023
    Citations: 19

  • Crystal structure and magnetic properties of a new layered sodium nickel hydroxide phosphate, Na 2 Ni 3 (OH) 2 (PO 4) 2
    O Yakubovich, G Kiriukhina, O Dimitrova, A Volkov, A Golovanov, ...
    Dalton Transactions 42 (41), 14718-14725 2013
    Citations: 18

  • Effect of cation on magnetic properties of double perovskite compounds: From ferromagnetic CaCrSbO to antiferromagnetic SrCrSbO
    S Baidya, T Saha-Dasgupta
    Physical Review B—Condensed Matter and Materials Physics 86 (2), 024440 2012
    Citations: 17

  • Theoretical evidence of spin-orbital-entangled state in the transition metal oxide
    CH Kim, S Baidya, H Cho, VV Gapontsev, SV Streltsov, DI Khomskii, ...
    Physical Review B 100 (16), 161104 2019
    Citations: 16

  • Confinement-driven electronic and topological phases in corundum-derived -oxide honeycomb lattices
    O Kksal, S Baidya, R Pentcheva
    Physical Review B 97 (3), 035126 2018
    Citations: 15

  • Controlled confinement of half-metallic two-dimensional electron gas in heterostructures: A first-principles study
    S Baidya, UV Waghmare, A Paramekanti, T Saha-Dasgupta
    Physical Review B 92 (16), 161106 2015
    Citations: 13

  • Phonon spectrum of and as evidence of coupling of the lattice with electronic and magnetic degrees of freedom
    Y Xu, H Man, N Tang, T Ohtsuki, S Baidya, S Nakatsuji, D Vanderbilt, ...
    Physical Review B 105 (7), 075137 2022
    Citations: 12

  • Copper rubidium diphosphate, Rb 2 Cu 3 (P 2 O 7) 2: synthesis, crystal structure, thermodynamic and resonant properties
    L Shvanskaya, O Yakubovich, A Ivanova, S Baidya, T Saha-Dasgupta, ...
    New Journal of Chemistry 37 (9), 2743-2750 2013
    Citations: 12

  • Understanding neutron scattering data in YMnO: An effective spin Hamiltonian
    S Baidya, P Sanyal, H Das, B Roessli, T Chatterji, T Saha-Dasgupta
    Physical Review B—Condensed Matter and Materials Physics 84 (5), 054444 2011
    Citations: 12