DCMPMS Seminars

Magnetic and magnetocaloric properties of rare earth intermetallic compounds RCoNi (R = Gd, Tb, Dy and Ho) and HoCo2-xNix (0 ≤ x ≤ 2)

by Dr. Rajib Mondal (Low Temperature Physics Lab., Department of Physics, Indian Institute of Technology Madras, Chennai)

Tuesday, August 2, 2016 from to (Asia/Kolkata)
at AG80
Description
Recently, magnetic refrigeration based on magnetocaloric effect (MCE) is considered to be potential alternative to the conventional refrigeration in terms of energy efficiency and environment friendliness. The magnetocaloric effect is an intrinsic property of the magnetic materials in which a reversible temperature change and magnetic entropy change is caused by the application or removal of magnetic field under adiabatic and isothermal conditions, respectively. It has been evidenced that the order of the magnetic transition also influences greatly the MCE of a material. The rare earth and transition metal based compounds, RT2 (R = Dy, Ho, Er and T = Co, Ni) exhibit large MCE near transition. While RCo2 (R = Dy, Ho and Er) compounds display large MCE caused by the first order metamagnetic transition at ferrimagnetic ordering (TC), RNi2 (R = Dy, Ho and Er) compounds display large MCE near their second order ferromagnetic transition. The partial substitution of Ni at Co-site of RCo2 affects the d-state near Fermi level of RCo2 compounds and hence it is expected to alter the associated magnetic and magnetocaloric properties. The partial substitution of Ni at Co-site of RCo2 compounds leads to the interesting magnetic and magnetocaloric properties. Substitution of Ni broadens the MCE curves, thereby leading to improve the cooling efficiency of the refrigerants. Large cooling efficiency with minimal thermal hysteresis loss due to second order magnetic transition at TC makes the Ni substituted RCo2 compounds potential magnetic refrigerants at low temperatures. In the talk, the structural, magnetic and magnetocaloric properties of cubic Laves phase rare earth intermetallic compounds RCoNi (R = Gd, Tb, Dy and Ho) and HoCo2-xNix (0 ≤ x ≤ 2) will be discussed [1-4].

References:
1.	Rajib Mondal, R. Nirmala, J. Arout Chelvane and S. K. Malik, J. Magn. Magn. Mater. 393, 376 (2015) 
2.	Rajib Mondal, R. Nirmala, J. Arout Chelvane and A. K. Nigam, Physica B 448, 9 (2014)
3.	Rajib Mondal, R. Nirmala, J. Arout Chelvane and A. K. Nigam, J. Appl. Phys. 113, 17A930 (2013) and references therein
4.	Rajib Mondal, J. Arout Chelvane and R. Nirmala, AIP Conference Proceedings 1447, 1115 (2012)