Magnetic properties and large inverse magnetocaloric effect in single crystal antiferromagnetic TbNiAl 4

Abstract

The magnetic properties and magnetocaloric effect (MCE) in single crystal antiferromagnetic TbNiAl 4 were systematically studied by examining the temperature and field dependence of magnetization and heat capacity. These magnetic properties and the MCE show strong magnetocrystalline anisotropy. A field-induced step-like magnetization transition and large inverse MCE were observed at low temperatures with the magnetic field parallel to the a axis but not for the b or c axes. Such strong anisotropy originates from the crystalline electric field interaction of the Tb 3+ ions. The large inverse MCE is related to the field-induced step-like magnetic behaviour which is probably due to a transition from a commensurate antiferromagnetic phase to an incommensurate magnetic phase. The values of maximum magnetic entropy change ( Δ S M max ) reach 5.0 and 7.9 J Kg −1 K −1 for field changes of 2 and 6 T ( H // a axis), respectively; the corresponding maximum adiabatic temperature changes ( Δ T a d max ) are evaluated to be 1.4 and 3.4 K for single crystal TbNiAl 4.