Post Doc: Low temp., superconductivity, magnetism: micro-SQUID-EPR at 30 mK on 3d/4f single molecule magnet spin qubits
EDUCATION
BSc (Physics): Jadavpur University, Kolkata
MSc (Physics): IIT Kanpur, India
PhD: IIT Kanpur, India
Post Doc: Karlsruhe Institute of Technology (KIT), Germany
RESEARCH, TEACHING, or OTHER INTERESTS
Condensed Matter Physics, Atomic and Molecular Physics, and Optics, Physical and Theoretical Chemistry
Ligand-field symmetry and magneto-optical correlations in a luminescent Dy(iii) single-molecule magnet Senthil Kumar Kuppusamy, Christian Pachl, Zhaoyang Jing, Sagar Paul, Benoît Heinrich, et al. Dalton Transactions, 2026 Magneto-optical correlations linking effective ligand-field (LF) symmetry and magnetization relaxation are presented for an emissive mononuclear Dy( iii) compound functioning as a single-molecule magnet (SMM).
Leveraging 3d-4f Coordination: Molecular Quantum Spring-Magnet Behavior in Axial Ni2Ln Complexes Zhaoyang Jing, Eufemio Moreno‐Pineda, Sagar Paul, Appu Sunil, Olaf Fuhr, et al. Angewandte Chemie International Edition, 2026 We report heterotrimetallic 3d–4f complexes, mimicking classical exchange spring magnets at the molecular scale. The complexes feature a linear Ni···Ln···Ni core, where the lanthanide ion is sandwiched between two Ni 2+ centers coordinated by N 3 O 3 ligand environments. The complexes are isostructural, while CASSCF calculations reveal collinear anisotropy axes and favorable electronic configurations for magnetic bistability in selected systems. Magnetic characterization via DC, AC, and µSQUID magnetometry down to 30 mK demonstrates slow magnetic relaxation and open hysteresis loops exclusively in Ni 2 Tb , Ni 2 Dy , and Ni 2 Ho . These systems exhibit ferromagnetic 3d‐4f coupling, while their isolated or antiferromagnetically coupled analogs ( Ni 2 Y , Zn 2 Tb / Dy ) and Ni 2 Er / Yb counterparts show fast relaxation and closed loops. Analysis suggests that the Ni 2+ ions alone, with modest anisotropy, deviate from the expected “hard” magnetic behavior due to a broad zero‐field QTM, while the Ln 3+ ions alone serve as the “soft” phase with large magnetic moments and sharp zero‐field QTM. Nevertheless, when brought together, their coupling and alignment of the anisotropy axis enhances the magnetic performance with exchange‐bias features mimicking the macroscopic exchange spring magnets. We highlight an optimal utilization of 3d‐4f coordination in designing molecular magnets with tunable relaxation and bistability, advancing prospects for quantum information and nanoscale magnetic devices.
Isolation of a planar π-aromatic Bi5− ring in a cobalt-based inverse-sandwich-type complex Julia Rienmüller, Benjamin Peerless, Sagar Paul, Florian Bruder, Wolfgang Wernsdorfer, et al. Nature Chemistry, 2025 Monocyclic π-aromatic compounds are ubiquitous throughout almost all fields of natural sciences—as synthons in industrial processes, as ligands of metal complexes for catalysis or sensing and as bioactive molecules. Planar organocycles stand out through their specific way of overcoming electron deficiency by a non-localizable set of (4n + 2)π electrons. By contrast, all-metal aromatic monocycles are still rare, as metal atoms prefer to form clusters with multiply bonded atoms instead. This limits the knowledge and potential of corresponding compounds in chemical syntheses or for innovative materials. Here we report the successful generation of Bi5 −, the heaviest analogue of (C5H5)−. Its use as a ligand in [{IMesCo}2(µ,η5:η5-Bi5)] (1) was realized by reacting (TlBi3)2− with [(IMes)2CoCl] (where IMes is bis(1,3-(2,4,6-trimethylphenyl))imidazol-2-ylidene) in ortho-difluorobenzene. Compound 1 is mixed-valence Co0/CoI as verified by µ-SQUID measurements and density functional theory, and embeds the planar Bi5 − cycle in an inverse-sandwich-type manner. Capturing Bi5 − represents a landmark in the chemistry of all-metal aromatic molecules and defines a new era for aromatic compounds.
Superconducting nitridized-aluminum thin films Alba Torras-Coloma, Leyre Martínez de Olcoz, Eva Céspedes, Elia Bertoldo, David López-Núñez, et al. Superconductor Science and Technology, 2024
Unconventional Nuclear-Spin-Dependent Toroidal Ground States in Isotopologue A Dy 4 [2 × 2] Complexes Y Chen, E Moreno-Pineda, S Paul, O Fuhr, D Fenske, W Wernsdorfer, ... Journal of the American Chemical Society , 2026 2026
Angle Resolved Magnetic Chirality Control in a Dy3 Single Molecule Toroic E Moreno-Pineda, S Paul, Z Zhu, S Liu, A Sunil, J Tang, W Wernsdorfer 2026
Homochiral toroidal spin state in Dy (III)-based single-molecule toroics Z Zhu, X Ying, LC Adi, C Zhao, EJM Chew, L Ungur, S Paul, ... Nature Chemistry, 1-10 , 2026 2026 Citations: 4
Nutzen der 3d‐4f Koordination: Molekulares Quanten‐Feder‐Magnet‐Verhalten in axialen Ni 2 Ln Komplexen Z Jing, E Moreno‐Pineda, S Paul, A Sunil, O Fuhr, Y Chen, ... Angewandte Chemie 138 (5), e22076 , 2026 2026
Leveraging 3d‐4f Coordination: Molecular Quantum Spring‐Magnet Behavior in Axial Ni 2 Ln Complexes Z Jing, E Moreno‐Pineda, S Paul, A Sunil, O Fuhr, Y Chen, ... Angewandte Chemie International Edition 65 (5), e22076 , 2026 2026 Citations: 1
Ligand-field symmetry and magneto-optical correlations in a luminescent Dy (III) singlemolecule magnet S Kumar Kuppusamy, C Pachl, Z Jing, S Paul, B Heinrich, O Fuhr, ... 2026
µSQUID-EPR Reveals Topologically Quenched Tunnelling in a Lanthanide Molecule W Wernsdorfer, S Paul, E Moreno-Pineda, CCMJ de Moreno, A Sunil, ... 2026
Ligand-field symmetry and magneto-optical correlations in a luminescent Dy (iii) single-molecule magnet SK Kuppusamy, C Pachl, Z Jing, S Paul, B Heinrich, O Fuhr, S Klyatskaya, ... Dalton Transactions 55 (14), 5448-5465 , 2026 2026
A Spin Frustrated Hourglass {Gd 9 } Molecular Nanomagnet with Unusual Magnetocaloric Properties SPK Panguluri, E Moreno-Pineda, C Molina-Jirón, S Paul, MUI Cervera, ... Journal of the American Chemical Society 147 (47), 43578-43583 , 2025 2025
Chiral Dysprosium-[7] Helicene Macrocycles Showing Record Single-Molecule Magnet Properties in the Lanthanide–Helicene Family Z Zhu, T Wang, LA Mariano, S Paul, W Wernsdorfer, A Lunghi, J Tang Journal of the American Chemical Society 147 (46), 42815-42824 , 2025 2025 Citations: 4
Ultraslow Relaxation of Toroidal State in Ferrotoroidal Dysprosium Complex D Chauhan, S Paul, D Borah, A Sunil, W Wernsdorfer, M Shanmugam, ... Journal of the American Chemical Society 147 (43), 39572-39581 , 2025 2025 Citations: 7
From Strong to Weak Interaction: Reconciling SQUID and µSQUID-EPR Data in Anomalous Co (II) Dimers S Paul, M Dolai, JN Goswami, B Bhattacharya, F Emmerling, MGB Drew, ... Inorganic Chemistry Frontiers , 2025 2025 Citations: 3
Deciphering the Magnetostructural Criteria in Dy III and Ho III Macrocycle-Based Single-Molecule Magnets with Pseudo- D 5h Symmetry: A Combined Single … AS Armenis, GP Bakali, S Paul, KN Pantelis, L Cunha-Silva, J Tang, ... Inorganic Chemistry 64 (23), 11476-11489 , 2025 2025 Citations: 6
Cover Feature: The Interplay of Single Ion Anisotropy and Magnetic 3 d ‐4 f Interactions in V III 2 Ln III 2 Butterfly Complexes (ChemistryEurope 3/2025) J Arneth, XF Li, J Braun, S Paul, M Schulze, CE Anson, W Wernsdorfer, ... ChemistryEurope 3 (3), e202580302 , 2025 2025
The Interplay of Single Ion Anisotropy and Magnetic 3 d ‐4 f Interactions in V III 2 Ln III 2 Butterfly Complexes J Arneth, XF Li, J Braun, S Paul, M Schulze, CE Anson, W Wernsdorfer, ... ChemistryEurope 3 (3), e202500011 , 2025 2025 Citations: 2
Isolation of a planar π-aromatic Bi 5 − ring in a cobalt-based inverse-sandwich-type complex J Rienmüller, B Peerless, S Paul, F Bruder, W Wernsdorfer, F Weigend, ... Nature Chemistry 17 (4), 547-555 , 2025 2025 Citations: 13
Unveiling the Werner-Type Cluster Chemistry of Heterometallic 4f/Post-Transition Metals: A {Dy 3 Bi 8 } Complex Exhibiting Quantum Tunneling Steps in the … KH Baka, D Liu, S Paul, W Wernsdorfer, J Tang, LF Chibotaru, ... Inorganic Chemistry 64 (4), 1962-1974 , 2025 2025 Citations: 3
π-Aromatic Bi5––The Heaviest Analogue of Cyclopentadienide (C5H5)–Finally Captured in the Mixed-Valent Compound [{IMesCo} 2 (μ, η5: η5-Bi5)] S Dehnen, F Weigend, W Wernsdorfer, J Rienmueller, B Peerless, S Paul 2024
Record quantum tunneling time in an air-stable exchange-bias dysprosium macrocycle Z Zhu, S Paul, C Zhao, J Wu, X Ying, L Ungur, W Wernsdorfer, F Meyer, ... Journal of the American Chemical Society 146 (28), 18899-18904 , 2024 2024 Citations: 50
Superconducting nitridized-aluminum thin films A Torras-Coloma, L Martínez de Olcoz, E Céspedes, E Bertoldo, ... Superconductor Science and Technology 37 (3), 035017 , 2024 2024 Citations: 11
MOST CITED SCHOLAR PUBLICATIONS
Record quantum tunneling time in an air-stable exchange-bias dysprosium macrocycle Z Zhu, S Paul, C Zhao, J Wu, X Ying, L Ungur, W Wernsdorfer, F Meyer, ... Journal of the American Chemical Society 146 (28), 18899-18904 , 2024 2024 Citations: 50
Insight into ferromagnetic interactions in Cu II–Ln III dimers with a compartmental ligand A Panja, S Paul, E Moreno-Pineda, R Herchel, NC Jana, P Brandão, ... Dalton Transactions 53 (6), 2501-2511 , 2024 2024 Citations: 22
Isolation of a planar π-aromatic Bi 5 − ring in a cobalt-based inverse-sandwich-type complex J Rienmüller, B Peerless, S Paul, F Bruder, W Wernsdorfer, F Weigend, ... Nature Chemistry 17 (4), 547-555 , 2025 2025 Citations: 13
Superconducting nitridized-aluminum thin films A Torras-Coloma, L Martínez de Olcoz, E Céspedes, E Bertoldo, ... Superconductor Science and Technology 37 (3), 035017 , 2024 2024 Citations: 11
Stochastic resonance in thermally bistable Josephson weak links and micro-SQUIDs S Paul, G Kotagiri, R Ganguly, H Courtois, CB Winkelmann, AK Gupta Physical Review Applied 15 (2), 024009 , 2021 2021 Citations: 11
Micron size superconducting quantum interference devices of lead (Pb) S Paul, S Biswas, AK Gupta Superconductor Science and Technology 30 (2), 025017 , 2017 2017 Citations: 8
Ultraslow Relaxation of Toroidal State in Ferrotoroidal Dysprosium Complex D Chauhan, S Paul, D Borah, A Sunil, W Wernsdorfer, M Shanmugam, ... Journal of the American Chemical Society 147 (43), 39572-39581 , 2025 2025 Citations: 7
Synthesis, characterization and magnetic properties of halogenated tetranuclear cubane-like nickel (ii) complexes M Aryaeifar, HA Rudbari, E Moreno-Pineda, JV Cuevas-Vicario, S Paul, ... New Journal of Chemistry 48 (8), 3603-3613 , 2024 2024 Citations: 7
Magnetization reversal across multiple serial barriers in a single nanoparticle S Paul, G Kotagiri, R Ganguly, A Subramanian, H Courtois, ... Physical Review B 105 (18), L180410 , 2022 2022 Citations: 7
Deciphering the Magnetostructural Criteria in Dy III and Ho III Macrocycle-Based Single-Molecule Magnets with Pseudo- D 5h Symmetry: A Combined Single … AS Armenis, GP Bakali, S Paul, KN Pantelis, L Cunha-Silva, J Tang, ... Inorganic Chemistry 64 (23), 11476-11489 , 2025 2025 Citations: 6
Magnetic behaviour of a spin-canted asymmetric lanthanide quinolate trimer L Batista, S Paul, C Molina-Jirón, JA Jaén, D Fensker, O Fuhr, M Ruben, ... Dalton Transactions 53 (31), 12927-12935 , 2024 2024 Citations: 5
Probing magnetism of individual nano-structures using Nb μ-SQUIDs in hysteresis free mode S Paul, G Kotagiri, R Ganguly, H Parashari, H Courtois, CB Winkelmann, ... Journal of Magnetism and Magnetic Materials 503, 166625 , 2020 2020 Citations: 5
Homochiral toroidal spin state in Dy (III)-based single-molecule toroics Z Zhu, X Ying, LC Adi, C Zhao, EJM Chew, L Ungur, S Paul, ... Nature Chemistry, 1-10 , 2026 2026 Citations: 4
Chiral Dysprosium-[7] Helicene Macrocycles Showing Record Single-Molecule Magnet Properties in the Lanthanide–Helicene Family Z Zhu, T Wang, LA Mariano, S Paul, W Wernsdorfer, A Lunghi, J Tang Journal of the American Chemical Society 147 (46), 42815-42824 , 2025 2025 Citations: 4
Modulating quantum tunnelling of magnetization in Dy isotopologue dimers TT Ruan, E Moreno-Pineda, S Paul, M Schulze, S Schlittenhardt, ... Dalton Transactions 53 (42), 17281-17290 , 2024 2024 Citations: 4
From Strong to Weak Interaction: Reconciling SQUID and µSQUID-EPR Data in Anomalous Co (II) Dimers S Paul, M Dolai, JN Goswami, B Bhattacharya, F Emmerling, MGB Drew, ... Inorganic Chemistry Frontiers , 2025 2025 Citations: 3
Unveiling the Werner-Type Cluster Chemistry of Heterometallic 4f/Post-Transition Metals: A {Dy 3 Bi 8 } Complex Exhibiting Quantum Tunneling Steps in the … KH Baka, D Liu, S Paul, W Wernsdorfer, J Tang, LF Chibotaru, ... Inorganic Chemistry 64 (4), 1962-1974 , 2025 2025 Citations: 3
The Interplay of Single Ion Anisotropy and Magnetic 3 d ‐4 f Interactions in V III 2 Ln III 2 Butterfly Complexes J Arneth, XF Li, J Braun, S Paul, M Schulze, CE Anson, W Wernsdorfer, ... ChemistryEurope 3 (3), e202500011 , 2025 2025 Citations: 2
Leveraging 3d‐4f Coordination: Molecular Quantum Spring‐Magnet Behavior in Axial Ni 2 Ln Complexes Z Jing, E Moreno‐Pineda, S Paul, A Sunil, O Fuhr, Y Chen, ... Angewandte Chemie International Edition 65 (5), e22076 , 2026 2026 Citations: 1
Design of a 3D vector magnet for micro-SQUID magnetometry S Paul, H Parashari, AK Gupta, G Sinha Proc. Indian Particle Accelerator Conf. , 2018 2018 Citations: 1
