Background

I completed my PhD under the supervision of Prof. C. V. Tomy from Department of Physics, Indian Institute of Technology Bombay, India. My research areas include Superconductivity and Magnetism. In my PhD, I studied the vortex phase transitions, vortex phase diagram and some metastability effects in the single crystals of some low T_c superconductors via detailed magnetization and electrical resistivity measurements.

At Warwick I worked as a Postdoctoral Researcher in the Superconductivity and Magnetism group from 2016 to 2020 under the supervision of G. Balakrishnan, M. R. Lees and J. B. Staunton working on some rare-earth transition-metal based permanent magnets.

Research Interests

I am an experimentalist. At Warwick I worked in a joint theoretical-experimental project, PRETAMAG focused on the physics underlying the principles of design of rare earth-transition metal based permanent magnets. The project aimed to uncover the key design principles of permanent magnets. I worked on the experimental side of this project where I performed detailed studies of the magnetic anisotropy, temperature dependence of magnetization and various other properties in the single crystals of these permanent magnets. My research work included the synthesis of high quality single crystals and polycrystalline samples of the rare-earth-transition-metal based permanent magnets. Optical floating zone technique and tetra-arc furnace were used to grow the single crystals of some of these permanent magnets. For the structural characterization of the samples, I used powder X ray diffraction, metallography preparing the metallographic slides and carrying out optical and SEM imaging to check phase purity. To study the direction-dependent properties, I aligned the single crystals using a back scattered X ray Laue system. I carried out detailed magnetic susceptibility measurements at both ambient pressure as well as at high pressure and torque measurements at various temperatures. The experimental results obtained were analysed and compared directly with the theoretical calculations carried out in parallel by our theory team working in this project.

Recent Research Highlights

Tunability of the spin reorientation transitions with pressure in NdCo5, Santosh Kumar, C. E. Patrick, R. S. Edwards, G. Balakrishnan, M. R. Lees, and J. B. Staunton, Applied Physics Letters 116, 102408 (2020).

Structural and magnetic properties of GdCo5-xNix, Amy L. Tedstone, Christopher E. Patrick, Santosh Kumar, Rachel S. Edwards, Martin R. Lees, Geetha Balakrishnan, and Julie B. Staunton, Structural and magnetic properties of GdCo5-xNix, Physical Review Materials 3, 034409 (2019).

Torque magnetometry study of the spin reorientation transition and temperature-dependent magnetocrystalline anisotropy in NdCo5, Santosh Kumar, C. E. Patrick, R. S. Edwards, G. Balakrishnan, M. R. Lees, J. B. Staunton, Journal of Physics: Condensed Matter 32, 255802 (2020)

Calculating the magnetic anisotropy of rare-earth transition-metal ferrimagnets, Christopher E. Patrick, Santosh Kumar, Geetha Balakrishnan, Rachel S. Edwards, M. R. Lees, Leon Petit, and Julie B. Staunton, Physical Review Letters 120, 097202 (2018).

Vortex phase diagram study in the superconductor Ca3Ir4Sn13, Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Mater. Res. Express 5, 106002 (2018).

Rare-earth/transition-metal magnetic interactions in pristine and (Ni,Fe)-doped YCo5 and GdCo5, Christopher E. Patrick, Santosh Kumar, Geetha Balakrishnan, Rachel S. Edwards, Martin R. Lees, Eduardo Mendive-Tapia, Leon Petit and Julie B. Staunton, Physical Review Materials 1, 024411 (2017).

Publications 2012 - 2019

1. Amy L. Tedstone, Christopher E. Patrick, Santosh Kumar, Rachel S. Edwards, Martin R. Lees, Geetha Balakrishnan, and Julie B. Staunton, Structural and magnetic properties of GdCo_5-xNi_x, Physical Review Materials 3, 034409 (2019).
2. Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Vortex phase diagram study in the superconductor Ca₃Ir₄Sn₁₃, Mater. Res. Express 5, 106002 (2018).
3. Christopher E. Patrick, Santosh Kumar, Kathrin Gotze, Matthew J Pearce, John Singleton, George Rowlands, Geetha Balakrishnan, Martin R. Lees, Paul A. Goddard and Julie B. Staunton, Field-induced canting of magnetic moments in GdCo₅ at finite temperature: first principles calculations and high-field measurements, J. Phys.: Condens. Matter 30, 32LT01 (2018).
4. Christopher E. Patrick, Santosh Kumar, Geetha Balakrishnan, Rachel S. Edwards, Martin R. Lees, Leon Petit and Julie B. Staunton, Calculating the magnetic anisotropy of rare-earth/transition-metal ferrimagnets, Phys. Rev. Lett. 120, 097202 (2018).
5. Christopher E. Patrick, Santosh Kumar, Geetha Balakrishnan, Rachel S. Edwards, Martin R. Lees, Eduardo Mendive-Tapia, Leon Petit and Julie B. Staunton, Rare-earth/transition-metal magnetic interactions in pristine and (Ni,Fe)-doped YCo₅ and GdCo₅, Physical Review Materials 1, 024411 (2017).
6. Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Unveiling of Bragg glass to vortex glass transition by an ac driving force in a single crystal of Yb₃Rh₄Sn₁₃, Supercond. Sci. Technol. 28, 085013 (2015).
7. Santosh Kumar, C. V. Tomy, G. Balakrishnan, D. McK Paul and A. K. Grover, Paramagnetic magnetization signals and curious metastable behaviour in field-cooled magnetization of a single crystal of superconductor 2H-NbSe₂, J. Phys. Condens. Matter 27, 295701 (2015).
8. Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Evidence of surface superconductivity and multi-quanta vortex states in a weakly-pinned single crystal of Ca₃Ir₄Sn₁₃, Physica C 509, 42-48 (2015).
9. Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Dual role of an ac driving force and the underlying two distinct order-disorder transitions in the vortex phase diagram of Ca₃Ir₄Sn₁₃, Physica C 506, 69-75 (2014).

Conference Proceedings-

1. C. Patrick, S. Kumar, L. Petit, E. Mendive-Tapia and J. Staunton, Magnetic properties of doped rare-earth/transition metal permanent magnets at finite temperature, IEEE International Magnetics Conference (INTERMAG) (2017).
2. Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Paramagnetic response and novel metastability effects in a single crystal of superconducting Ca₃Ir₄Sn₁₃, AIP Conf. Proc. 1731, 130013 (2016).
3. Santosh Kumar, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Angular dependent study of spatial order-disorder transitions in the vortex matter of superconducting Yb₃Rh₄Sn₁₃, AIP Conf. Proc. 1728, 020625 (2016).
4. Santosh Kumar, Varun K. Kushwaha, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover, Elucidation of Peak Effect Phenomenon in a Single Crystal of Superconducting Ca₃Ir₄Sn₁₃, AIP Conf. Proc. 1665, 130009 (2015).
5. Santosh Kumar, C. V. Tomy, A. K. Grover, G. Balakrishnan and D. McK Paul, Crossover from more to less ordered vortex state on field-cooling a weakly-pinned crystal of Ca₃Rh₄Sn₁₃, AIP Conf. Proc. 1512, 1202-1203 (2013).
6. Santosh Kumar, Ajay D. Thakur, Ravi P. Singh, A. Thamizhavel, C. V. Tomy and A. K. Grover,Multi-quanta vortex states, crossover to Abrikosov Lattice and peak effect phenomenon in Ca₃Ir₄Sn₁₃, AIP Conf. Proc. 1447, 909 (2012).

Write to

If you have any questions about the research work carried out by Dr Santosh Kumar while at Warwick please email:

g dot balakrishnan at warwick dot ac dot uk

or

m dot r dot lees at warwick dot ac dot uk

Contact Details

Present Address

E-Mail

santosh dot kumar at iitdh dot ac dot in