Critical behavior and magnetocaloric effect of the ferromagnetic Weyl semimetal candidate Co2−xZrSn single crystals

Abstract

We carried out a comprehensive investigation of the magnetic critical properties and the magnetocaloric effect of the ferromagnetic Weyl semimetal candidate Co2−xZrSn (x ≈ 0.41) single crystals. Contrary to the result of polycrystalline samples, the magnetic properties cannot be described by the mean-field model. The critical exponents β = 0.443(1) with TC= 192.2(1) K, γ = 1.338(11) with TC= 192.5(1) K, and δ = 4.14(6) at TC ~ 192 K suggest a three-dimensional long-range magnetic coupling with the exchange distance decaying as J(r) ~ r−4.9, which lies between the 3D Heisenberg model and the mean-field model. Moreover, the magnetic entropy change −ΔSM gets a maximum value around TC. The peak position of −ΔSM exhibits a small shift toward high temperature with an increasing of field, further excluding the mean-field model. The renormalized −ΔSM(T, H) plots fall into a universal curve, verifying a second-order phase transition and reliability of the deduced critical exponents.