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Dr Santosh Kumar

Background

I am currently working as a Postdoctoral Researcher in the Superconductivity and Magnetism group joined in Jan 2016 under the supervision of G. Balakrishnan, M. R. Lees and J. B. Staunton. 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 have studied the vortex phase transitions, vortex phase diagram and some metastability effects in the single crystals of some low Tc superconductors via detailed magnetization and electrical resistivity measurements. In the current postdoctoral work, I am working on some rare-earth transition-metal based permanent magnets.

Research Interests

I am an experimentalist working 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 aims to uncover the key design principles of permanent magnets. I am working from the experimental side of this project where I perform a detailed study of magnetic anisotropy, temperature dependence of magnetization and various other properties in the single crystals of these permanent magnets. My research work includes 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 have been utilized to grow the single crystals of some of these permanent magnets. For the structural characterization of the samples, I have been using the powder X ray diffraction technique, preparing the metallographic slides and carrying out their optical imaging to check the phase purity. To study the direction-dependent properties, I align the single crystals using backscattered X ray Laue system. I carry out the detailed magnetic susceptibility measurements at both ambient pressure as well as at high pressure and torque measurements at various temperatures. The experimental results obtained are analysed and compared directly with the theoretical calculations carried out in parallel by our theory team working in this project.

Recent Research Highlights

A. Tedstone et al., Physical Review Materials 3, 034409 (2019)

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).

C. E. Patrick et al., Physical Review Letters 120, 097202 (2018)

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).

Santosh Kumar et al., Material Research Express 5, 106002 (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).

C. E. Patrick et al., Physical Review Materials 1, 024411 (2017)

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

  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 GdCo5-xNix, 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).

Santosh_Photo

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Contact Details

Department of Physics
University of Warwick
Coventry CV4 7AL
United Kingdom

Contact Details

Office
P230

Telephone
+44 (0)24 765 22329
Fax
+44 (0)2476150897
E-Mail

S dot Kumar dot 1 at warwick dot ac dot uk