Anisotropic magnetic entropy change in the hard ferromagnetic semiconductor VI3

Layered VI3 has emerged as a new two-dimensional (2D) van der Waals bonded ferromagnetic semiconductor, which is an important class of materials for spintronics applications. However, the origin of ferromagnetism in VI3 is still missing. In this work, we systematically investigate the anisotropy of magnetic properties and entropy change in a VI3 single crystal. Based on the measurement of the angular-dependent magnetization, there is a weak sixfold in-plane symmetry and fourfold out-of-plane symmetry, indicating VI3 possesses weak in-plane anisotropy and large out-of-plane anisotropy. Meanwhile, anisotropy of magnetic entropy change Delta S-M(T, H) is further studied by the isothermal magnetization, showing that the difference of -Delta S-M(max) between the c axis and ab plane reaches a maximum value similar to 0.95 J kg(-1) K-1 with a magnetic field change of 4.5 T. With the scaling analysis of Delta S-M, the critical exponents can be obtained and indicate a crossover between 2D-Ising and tricritical mean-field magnetic interactions, and the rescaled Delta S-M(T, H) curves fall onto a universal curve, demonstrating a second-order type of magnetic transition.