近日，德国马克斯·普朗克固体研究所的B. Keimer&C. T. Suen及其研究小组与加拿大不列颠哥伦比亚大学的A. Damascelli等人合作并取得一项新进展。经过不懈努力，他们揭示莫特绝缘子在电流感应绝缘子到金属转变时的电子响应。相关研究成果已于2024年9月24日在国际知名学术期刊《自然—物理学》上发表。

该研究团队展示了电流诱导对Ca₂RuO₄电子态的改性作用。通过结合四探针电输运测量的角度分辨光电子能谱（输运-ARPES）技术，研究人员观察到莫特能隙的显著减小以及钌能带色散的改变。基于自由能分析，研究人员证明了电流诱导相在电子特性上与高温零电流金属相截然不同。这项研究结果凸显了电流驱动的绝缘体-金属转变中，晶格依赖与轨道依赖电子响应之间的强烈相互作用。

据悉，莫特绝缘体Ca₂RuO₄表现出由直流电流诱导的绝缘体-金属转变。尽管与此转变相关的结构变化已得到全面研究，但对电子自由度响应的全面理解仍然不足。

附：英文原文

Title: Electronic response of a Mott insulator at a current-induced insulator-to-metal transition

Author: Suen, C. T., Markovi, I., Zonno, M., Heinsdorf, N., Zhdanovich, S., Jo, N. H., Schmid, M., Hansmann, P., Puphal, P., Frsich, K., Smit, S., Au-Yeung, C., Zimmermann, V., Zwartsenberg, B., Krautloher, M., Elfimov, I. S., Koch, R., Gorovikov, S., Jozwiak, C., Bostwick, A., Franz, M., Rotenberg, Eli, Keimer, B., Damascelli, A.

Issue&Volume: 2024-09-24

Abstract: The Mott insulator Ca₂RuO₄ exhibits an insulator-to-metal transition induced by d.c. current. Despite the thorough examination of the structural changes associated with this transition, a comprehensive knowledge of the response of electronic degrees of freedom is still lacking. Here we demonstrate current-induced modifications of the electronic states of Ca₂RuO₄. Angle-resolved photoemission spectroscopy in conjunction with four-probe electrical transport (transport-ARPES) measurements reveal a clear reduction of the Mott gap and a modification in the dispersion of the Ru bands. Based on a free-energy analysis, we show that the current-induced phase is electronically distinct from the high-temperature zero-current metallic phase. Our results highlight strong interplay of lattice- and orbital-dependent electronic responses in the current-driven insulator-to-metal transition.

DOI: 10.1038/s41567-024-02629-3

Source: https://www.nature.com/articles/s41567-024-02629-3