Asymmetric hysteresis loop due to hidden local magnetic state in a Weyl semimetal

Magnetic Weyl semimetals, which couple magnetic order with topological features, have emerged as promising candidates for advanced applications based on topological materials. The switching of magnetization and the driving of domain wall motion play key roles in developing such applications. In this study, we propose that a type of hard-magnetic nuclei dominates the magnetic reversal and induces an asymmetric hysteresis loop, which resembles exchange bias effect. The sign change of this bias-like behavior can be realized by controlling the orientation of these hard-magnetic nuclei. Notably, these nuclei can retain their magnetic orientation at temperatures well above the material’s Curie temperature, suggesting the existence of a local magnetic state with non-zero magnetization and high stability. Our study offers a new scenario for manipulating the magnetic reversal and provides further insights into the magnetism of this Weyl system.