We have investigated the magnetic and magnetocaloric properties of van der Waals (vdW) layered CrCl3 from magnetization and heat capacity measurements. CrCl3 exhibits complicated magnetic properties due to the strong competition between the ferromagnetic and antiferromagnetic interactions: a ferromagnetic ordering around 17 K followed by an antiferromagnetic ordering at 14.3 K. A large magnetic entropy change (−ΔSM) of 19 J kg−1 K−1, an adiabatic temperature change (ΔTad) of 6.2 K, and a relative cooling power of 600 J kg−1 are observed for a field change of 7 T near the transition temperature, and the mechanical efficiency (ηm) at 18 K and 0–3 T is 1.17. These values of magnetocaloric parameters are significantly larger than those for CrI3 and other layered vdW systems. The scaling analysis shows that all the rescaled ΔSM(T, H) data collapse into a single curve, which indicates the second order nature of magnetic phase transition. The above results suggest that environmentally friendly CrCl3 can be a phenomenal alternative to very expensive rare-earth material for the magnetic refrigeration for liquefaction of hydrogen.
The discovery of skyrmions has recently sparked tremendous interest in topologically nontrivial spin textures. The signature of the noncoplanar nature of magnetic moments can be observed as topological Hall effect (THE) in electrical measurement. Realization of such nontrivial spin textures in new materials and through new routes is an ongoing endeavor due to their huge potential for future ultra‐dense, low‐power memory applications. In this work, oxygen vacancy (OV)‐induced THE and anomalous Hall effect (AHE) in a 5d0 system KTaO3 are reported. The observation of weak antilocalization behavior and THE in the same temperature range strongly implies the crucial role of spin–orbit coupling (SOC) behind the origin of THE. Ab initio calculations reveal the formation of the magnetic moment on Ta atoms around the OV and Rashba‐type spin texturing of conduction electrons. In the presence of Rashba SOC, the local moments around vacancy can form bound magnetic polarons (BMPs) with noncollinear spin texture, resulting in THE. Scaling analysis between transverse and longitudinal resistance establishes skew scattering‐driven AHE in the present case. This study opens a route to realize topological phenomena through defect engineering.
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