Investigation of field-controlled magnetocaloric switching effect in single crystal antiferromagnetic MnBi2Te4

Abstract

Being the first intrinsic antiferromagnetic (AFM) topological insulator (TI), MnBi₂Te₄, has garnered significant attention as an ideal platform for realizing diverse exotic topological quantum states. However, little is known about the magnetocaloric properties of MnBi₂Te₄ to date. In this work, we report the magnetocaloric effect, rotating magnetocaloric effect, and magnetocaloric switching effect of single-crystal MnBi₂Te₄. Under 0–9 T, the maximum magnetic entropy changes (−ΔS_M) obtained are 2.5 J kg⁻¹ K⁻¹ and 2.1J kg⁻¹ K⁻¹, when H∥c and H∥ab, respectively. Furthermore, the anisotropy in the −ΔS_M between the two crystallographic orientations gives MnBi₂Te₄ single crystals a rotational magnetocaloric effect. The sample exhibits a rotating entropy change of 0.4J kg⁻¹ K⁻¹ under a magnetic field of 9 T as the magnetic field is rotated from the ab plane to the c axis. More importantly, MnBi₂Te₄ exhibits a coexistence of conventional and inverse magnetocaloric effects by switching between them at a specific temperature and magnetic field, that is, the magnetocaloric switching effect. Moreover, the switching temperature of MnBi₂Te₄ can be modulated by changing the magnetic field, so that it is suitable for various constant-temperature baths. This study provides a meaningful clue for the design and exploration of high performance MCE-based constant-temperature devices.