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Seminar of International Laboratory of High Magnetic Fields and Low Temperatures PAS

Multifunctional phenomena in rare-earth intermetallic compounds with a Laves phase structure: Giant magnetostriction and magnetocaloric effect

Irina Tereshina

Baikov Institute of Metallurgy and Material Science of RAS”, Moscow, Russia

We report the magnetic and thermal properties (magnetization, specific heat, thermal expansion, magnetostriction and magnetocaloric effect) for the three multicomponent systems Tb_xDy_yGd_zCo₂,Tb_xDy_yHo_zCo₂ and Tb_xDy_yEr_zCo₂ (x+y+z=1). The Curie temperatures T_С of Tb_xDy_yR_zCo₂ranging from 130 to 300 K and the transition order (first or second) are found to depend on the composition of the materials. The highest MCE values (ΔT_ad/μ₀ΔH =1.2 - 1.5 K/T, where ΔТ_ad is the adiabatic temperature change in a variable magnetic field) are observed for the compounds exhibiting the transitions of the first order. Giant volume magnetostriction of (1.5 - 2)×10-3 and (0.5 - 0.6)×10-3 is demonstrated at field of μ₀H = 10T and 1.2T, respectively. Structural and magnetic entropy contributions to the total isothermal entropy change in Tb_xDy_yR_zCo₂ alloys are estimated. Regular recurrence and/or change of the physical properties across the varied composition of the compounds allows us to find the materials with desired magnetic characteristics such as T_C and MCE as well as magnetostriction values in order to use them in practice.