Equiatomic rare earth intermetallic compounds RNi (R = heavy rare earth such as Gd, Tb, Dy, Ho and Er) exhibit excellent magnetocaloric effect near their ferromagnetic ordering temperature and alloying the rare earth site has been found to be an efficient method to tailor the magnetic transition temperature and the associated magnetic entropy change 1. In the present work, three rare earth elements Tb, Ho and Er in equimolar concentration occupy the rare earth site in RNi compound. Polycrystalline Tb0.33Ho0.33Er0.33Ni has been prepared by arc-melting under argon atmosphere and characterized by powder X-ray diffraction and magnetization measurements. Multicomponent Tb0.33Ho0.33Er0.33Ni compound has FeB-type orthorhombic crystal structure (space group Pnma, No.62) at room temperature. The sample orders ferromagnetically at ~59 K (TC) Fig. 1a. Paramagnetic susceptibility is Curie-Weiss like Inset in Fig. 1a. It should be recalled that the compounds with individual rare-earths viz. TbNi, HoNi and ErNi order ferromagnetically at about 67 K, 36 K and 11 K respectively. Magnetization has been measured at 5 K as a function of magnetic field up to 70 kOe. Magnetization saturates in applied magnetic field Fig. 1b and the saturation magnetization value is about 9.9 µB/f.u. A minor hysteresis with a coercive field of ~930 Oe is observed. By measuring isothermal magnetization data around TC, magnetocaloric effect is estimated. A moderate isothermal magnetic entropy change has been obtained near TC that is of the same order as in the end member RNi compounds. Understanding magnetic properties of such multicomponent rare earth intermetallic compounds should pave a way to comprehend the complex magnetism of rare earth high-entropy alloys.
References:
1. X. Q. Zheng, B. Zhang, H. Wu, F. X. Hu, Q. Z. Huang and B. G. Shen, J. Appl. Phys. 120 (2016) 163907

Fig. 1. (a) Magnetization vs temperature and (b) magnetization vs field of Tb0.33Ho0.33Er0.33Ni compound.