Hardeep Kumar
@nituk.ac.in
Assistant Professor, Physics
NIT Uttarakhand
Dr. Hardeep Kumar received his B.Sc. degree in Non-Medical from Himachal Pradesh University, Shimla in 2002 and M.Sc. degree in Physics from Guru Nanak Dev University Amritsar in 2004. He obtained Ph.D. degree in Physics from I.I.T. Delhi in 2011. His Ph.D. work is based on magnetic granular thin films. Dr. Hardeep worked as FAPESP Post-doctoral Fellow at University of Sao Paulo, Brazil from 09/2011 to 05/2014 and joined Amity University UP, Noida as Assistant Professor in 10/2014 and worked there for about 3 Year and 7 Months. He joined NIT Uttarakhand as Assistant Professor in 06/2018. Dr. Hardeep has co-supervised one Ph.D. scholar (07/2016-03/2021), and currently two Ph.D. students are working under his sole supervision in the area of Spintronics . He completed one research project (2016-19) sponsored by UGC-DAE CSR , Indore, and currently working on a project (2020-till date) sponsored by UGC-DAE CSR , Indore. His research interests are magnetic heterostructures for spintronics ap
EDUCATION
* Ph.D. (Physics) - Indian Institute of Technology Delhi, India - 2011
* M.Sc. (Physics) - GNDU Amritsar, India - 2004
RESEARCH INTERESTS
Magnetism, Thin films, Spintronics, Ion-irradiation, Hydrogen sensors
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Preeti Negi, Mukul Gupta, Rajeev Rawat, Rajeev Joshi, Harsh Bhatt, Surendra Singh, V.R. Reddy, and Hardeep Kumar
Elsevier BV
C. Lakshmi Ranganatha, B. S. Palakshamurthy, G. P. Abhilash, Anu Mathew, H. M. Suresh Kumar, and C. Shivakumara
Springer Science and Business Media LLC
Hardepinder Singh, Mukul Gupta, Pooja Gupta, Rafaela F. S. Penacchio, Sergio L. Morelhao, and Hardeep Kumar
Springer Science and Business Media LLC
Hardeep Kumar, Sergio L. Morelhao, Gerson Pessotto, Hardepinder Singh, Anil K. Sinha, and Daniel R. Cornejo
Journal of Magnetism and Magnetic Materials Elsevier BV
Deepti, Bhawini Tripathi, Hardeep Kumar, Ambuj Tripathi, Sunil Kumar, Saif Ahmad Khan, G.B.V.S. Lakshmi, Arka Bikash Dey, Gagan Sharma, Ajay Gupta,et al.
Elsevier BV
Deepti, Hardeep Kumar, Ambuj Tripathi, Arka Bikash Dey, Mukul Gupta, Richa Krishna, and D.K. Avasthi
Elsevier BV
Debalaya Sarker, Saswata Bhattacharya, H. Kumar, Pankaj Srivastava, and Santanu Ghosh
Springer Science and Business Media LLC
AbstractThe reliance of modern electronic era on ultrafast data recording has made the search for novel tools to tune nano-scale magnetic-anisotropy (MA) never-ending. We demonstrate a strong correlation between the spin-spin interactions, local atomic structure and the MA of Ni nanoparticles (NPs) embedded inside SiO2 matrix under swift heavy ion (SHI) irradiation. In contrast to traditional understandings, MA in Ni NPs along with their aspect ratio, first increases upto 5 × 1013 ions/cm2 SHI fluence (5e13) and gets reduced at highest fluence. Using angle dependent Extented-Xray-Absorption-Fine-Structure (EXAFS) and ab initio molecular dynamics (MD) simulations, we show that the anisotropy induced in local atomic structure upon irradiation is dependent on atomic spin-spin interactions, which gets reduced at highest fluence. The chosen model cluster (Ni38) used in our MD simulations is duly validated by comparing the pair-correlation-function of the structure with the EXAFS-Fourier-Transform. The lattice temperatures for the films irradiated at different fluences, as calculated from thermal-spike-model, are used for the respective MD runs. We conclude that the enhanced disorder in both the local atomic environment and spin alignment destroys the MA at the highest fluence in SHI irradiated Ni NPs. The findings therefore provide rich conceptual insights for designing magnetic devices using SHI-induced phenomena.
H. Kumar, D. R. Cornejo, S. L. Morelhao, S. Kycia, I. M. Montellano, N. R. Álvarez, G. Alejandro, and A. Butera
AIP Publishing
In this work, we report the experimental results obtained on a set of ∼90 nm thick FeRh epitaxial films deposited on MgO (001), MgO (111), and Al2O3 (0001) single crystal substrates. The magnetic characterization was achieved by measuring magnetization curves and ferromagnetic resonance as a function of temperature and orientation of the films with respect to the applied magnetic field. We discuss our results by comparing the characteristics of the antiferromagnetic-ferromagnetic transition among FeRh films of the same thickness but exposed to different post-growth annealings and deposited on substrates of different crystalline orientations. We have found that there is a correlation between the strain present in the films and their magnetic behavior, observing that a change in the in-plane stress from compressive to tensile tends to shift the magnetic transition by more than 60 K. The interplay between magnetic and elastic properties was further analyzed by ferromagnetic resonance, and we have found that the magnetoelastic component of the anisotropy varies from out-of-plane to in-plane, depending on the substrate. These findings could be of great importance if a precise tuning of the magnetic transition temperature or the magnetic anisotropy is needed for a specific application.In this work, we report the experimental results obtained on a set of ∼90 nm thick FeRh epitaxial films deposited on MgO (001), MgO (111), and Al2O3 (0001) single crystal substrates. The magnetic characterization was achieved by measuring magnetization curves and ferromagnetic resonance as a function of temperature and orientation of the films with respect to the applied magnetic field. We discuss our results by comparing the characteristics of the antiferromagnetic-ferromagnetic transition among FeRh films of the same thickness but exposed to different post-growth annealings and deposited on substrates of different crystalline orientations. We have found that there is a correlation between the strain present in the films and their magnetic behavior, observing that a change in the in-plane stress from compressive to tensile tends to shift the magnetic transition by more than 60 K. The interplay between magnetic and elastic properties was further analyzed by ferromagnetic resonance, and we have found that ...
R. Della Noce, A.V. Benedetti, M. Magnani, E.C. Passamani, H. Kumar, D.R. Cornejo, and C.A. Ospina
Elsevier BV
Debalaya Sarker, H. Kumar, Rajkumar Patra, D. Kabiraj, D. K. Avasthi, Sarathlal K. Vayalil, S. V. Roth, P. Srivastava, and S. Ghosh
AIP Publishing
The field emission (FE) properties of nickel nanoparticles embedded in thin silica matrix irradiated with 100 MeV Au+7 ions at various fluences are studied here. A large increase in FE current density is observed in the irradiated films as compared to their as deposited counterpart. The dependence of FE properties on irradiation fluence is correlated with surface roughness, density of states of valence band and size distribution of nanoparticles as examined with atomic force microscope, X-ray photoelectron spectroscopy, and grazing incidence small angle x-ray scattering. A current density as high as 0.48 mA/cm2 at an applied field 15 V/μm has been found for the first time for planar field emitters in the film irradiated with fluence of 5.0 × 1013 ions/cm2. This significant enhancement in the current density is attributed to an optimized size distribution along with highest surface roughness of the same. This new member of field emission family meets most of the requirements of cold cathodes for vacuum mic...
S. Ghosh, H. Kumar, S. P. Singh, P. Srivastava, D. Kabiraj, D. K. Avasthi, D. Bürger, S. Zhou, A. Mücklich, H. Schmidt,et al.
Springer International Publishing
A.M.P. Sakita, E.C. Passamani, H. Kumar, D.R. Cornejo, C.S. Fugivara, R.D. Noce, and A.V. Benedetti
Elsevier BV
Hardeep Kumar, Marcia C. A. Fantini, and Daniel R. Cornejo
Institute of Electrical and Electronics Engineers (IEEE)
Fe100-xRhx films were deposited on Si substrates with various Rh concentrations (conc.) (x) ~ 32 to 52% at. All the films showed the in-plane magnetic anisotropy due to the thin-film like structure i.e., shape anisotropy. For Rh conc. up to ~ 42% at., the films exhibit a single ferromagnetic (α') phase. However, for Rh conc. (x) > 42% at., there exists a mixture of ferromagnetic (α') and antiferromagnetic (α") phase. Nearly equiatomic samples ( x ~ 48 to 52% at.) showed abrupt enhancement in coercivity and a broad thermal hysteresis. This behavior is consistent with the presence of a mixture of FM and AFM phase. Thermal first-order-reversal-curves analysis showed that the AFM to FM phase transition is restricted to a region with FWHM of ~ T = 40 K, in spite of the mentioned broad thermal hysteresis.
Hardeep Kumar, L. Olivi;G. Aquilanti, S. Ghosh, P. Srivastava, D. Kabiraj, and D. K. Avasthi
International Association of Advanced Materials
A series of FeCo-SiO2 granular films of different FeCo atomic concentration (33-54%) have been prepared by fast atom beam sputtering technique and post-annealed in inert (Ar) and reducing (H2) gas environments. Fe and Co K-edge XANES analysis of as-deposited films indicate that both Fe and Co are present mainly in their elemental (Fe 0 , Co 0 ) state. A partial oxidation of Fe and Co is observed, as the FeCo alloy content decreases (54 to 33%) due to reduced particle size. XANES/XAFS analysis shows the formation of FeCo alloy with bcc Fe structure in H2 environment annealed films. The XRD and Raman analysis of Ar environment annealed films suggest the formation of Co3O4 and CoFe2O4 phases. The Ar environment is found not to be effective reducing medium to stabilize the FeCo alloy phase, while H2 environment annealing (450-700 o C) leads to formation of bcc FeCo alloy. Copyright © 2013 VBRI press.
R.D. Noce, A.V. Benedetti, E.C. Passamani, H. Kumar, D.R. Cornejo, and M. Magnani
Elsevier BV
Nitin Bindal, Manisha Sharma, H. Kumar, S. Sharma, S. C. Upadhaya, S. K. Tripathi, Keya Dharamvir, Ranjan Kumar, and G. S. S. Saini
AIP
Cadmium doped zinc oxide polycrystalline nano thin films were deposited on microscopic glass substrates following a modified chemical bath technique called Successive Ionic Layer Adsorption and Reaction (SILAR). Cadmium doping was found to increase the film grown rate. The X‐ray diffraction pattern showed that films have polycrystalline nature. The SEM image revealed growth of large crystallites perpendicular to the substrates. The optical transmittance spectra indicate that these thin films have the direct energy band gap. The resistivity of these films decreased with increase in the temperature for all compositions, which confirmed the semiconducting nature of films.
Hardeep Kumar, Santanu Ghosh, Danilo Bürger, Lin Li, Shengqiang Zhou, Debdulal Kabiraj, Devesh Kumar Avasthi, Rainer Grötzschel, and Heidemarie Schmidt
AIP Publishing
In this work, we report the effect of FeCo atomic fraction (0.33 < x < 0.54) and temperature on the electrical, magnetic, and tunneling magnetoresistance (TMR) properties of FeCo-Si-O granular films prepared by atom beam sputtering technique. Glancing angle x-ray diffraction and TEM studies reveal that films are amorphous in nature. The dipole–dipole interactions (particle–matrix mixing) is evident from zero-field cooled and field-cooled magnetic susceptibility measurements and the presence of oxides (mainly Fe-related) is observed by x-ray photoelectron spectroscopy analysis. The presence of Fe-oxides is responsible for the observed reduction of saturation magnetization and rapid increase in coercivity below 50 K. TMR has been observed in a wide temperature range, and a maximum TMR of −4.25% at 300 K is observed for x = 0.39 at a maximum applied field of 60 kOe. The fast decay of maximum TMR at high temperatures and lower TMR values at 300 K when compared to PFeCo2/(1+PFeCo2), where PFeCo is the spin pol...
Hardeep Kumar, Santanu Ghosh, Devesh Kumar Avasthi, Debdulal Kabiraj, Arndt Mücklich, Shengqiang Zhou, Heidemarie Schmidt, and Jean-Paul Stoquert
Springer Science and Business Media LLC
Hardeep Kumar, Santanu Ghosh, D.K. Avasthi, D. Kabiraj, N.P. Lalla, T. Shripathi, and J.C. Pivin
Elsevier BV
Hardeep Kumar, Santanu Ghosh, Danilo Bürger, Shengqiang Zhou, Debdulal Kabiraj, Devesh Kumar Avasthi, Rainer Grötzschel, and Heidemarie Schmidt
AIP Publishing
In this work we report on the synthesis of Ni:SiO2 nanogranular films with different metal fraction (0.10≤x≤0.68) and a homogeneous distribution of Ni particles by atom beam sputtering technique and on the study of their microstructure, electrical transport, magnetic properties, and on the observation of extraordinary Hall effect (EHE). Films with the Ni fraction x above percolation threshold (x≥0.58>xp) as revealed by resistivity versus temperature measurements have a large Ni particle size, pronounced ferromagnetic characteristics, and appreciable extraordinary Hall resistivity at 300 K. Furthermore, films above percolation have a relatively low, nearly temperature independent Ohmic resistivity smaller than 10−3 Ω cm and may be useful for Hall sensor applications. On the other hand, films below percolation threshold (x≤0.54 xp) show ferromagnetic characteristics with an enha...
Y.K. Mishra, V.S.K. Chakravadhanula, U. Schürmann, Hardeep Kumar, D. Kabiraj, S. Ghosh, V. Zaporojtchenko, D.K. Avasthi, and F. Faupel
Elsevier BV
Hardeep Kumar, Y.K. Mishra, S. Mohapatra, D. Kabiraj, J.C. Pivin, S. Ghosh, and D.K. Avasthi
Elsevier BV