Tunable colossal negative magnetoresistance of topological semimetal EuB6 thin sheets

作者：K. Zhu 祝, Qi 琦 Qi 齐, Yaofeng 耀锋 Xie 谢, L. Pan 潘, Senhao 森浩 Lv 吕, Guojing 国静 Hu 胡, Z. Zhao 赵, G. Xian 冼, Yechao 烨超 Han 韩, L. Bao 鲍, Y. Zhang 张, X. Lin 林, H. Guo 郭, H. Yang 杨, H. Gao 高 · 发表于：Chinese Physics B · 年份：2025 · DOI：10.1088/1674-1056/add5ca · 研究领域：Physics

EuB6, a magnetic topological semimetal, has attracted considerable attention in recent years due to its rich intriguing physical properties, including a colossal negative magnetoresistance (CNMR) ratio exceeding −80%, a topological phase transition and a predicted quantum anomalous Hall effect (QAHE) approaching the two-dimensional (2D) limit. Yet, studies of the influence of the dimensionality approaching 2D on the electronic transport properties of EuB6 are still scarce. In this work, EuB6 thin sheets with thicknesses ranging from 35 μm to 180 μm were successfully fabricated through careful mechanical polishing of high-quality EuB6 single crystals. The reduced thickness, temperature and magnetic field have a strong influence on the electronic transport properties, including the CNMR and carrier concentration of EuB6 thin sheets. As the thickness of EuB6 thin sheets decreases from 180 μm to 35 μm, the magnetization transition temperature and the corresponding suppressing temperature of the Kondo effect decrease from 15.2 K to 10.9 K, while the CNMR ratio increases from −87.2% to −90.8%. Furthermore, the weak antilocalization effect transits to a weak localization effect and the carrier concentration increases by 9.4% at 30 K in a 35 μm EuB6 thin sheet compared to the value reported for a 180 μm thin sheet. Our findings demonstrate an obvious tunable effect of the reduced dimensionality on the transport properties of EuB6 along with the temperature and magnetic field, which c...