近日，东南大学的苗霖及其研究小组与上海交通大学的钱冬等人合作并取得一项新进展。经过不懈努力，他们揭示d电子相关半导体FeSb₂中自旋态激发的光谱证据。相关研究成果已于2024年7月2日在国际知名学术期刊《美国科学院院刊》上发表。

本文利用X射线吸收光谱和原子多重态模拟，观察了FeSb₂中3d⁶组态的混合自旋态。此外，研究人员揭示了电导率的增强，无论是由温度还是掺杂引起的，其特征是由低自旋态填充到高自旋态。这项研究工作构成了重要的光谱证据，证明FeSb₂中的电/磁跃迁与自旋态激发直接相关。

据悉，锑化铁(FeSb₂)由于其令人费解的电子性质，已经被研究了几十年。它经历了从绝缘体到不确定金属的温度控制跃迁，以及从抗磁性到顺磁性的交叉。目前，各方已做了大量努力，但尚未形成共识。尽管宏观上的输运特性和磁测量数据可以通过多种理论模型进行解释，但识别其物理本质所需的基本光谱证据却仍然处于缺失状态。

附：英文原文

Title: Spectroscopic evidence of spin-state excitation in d-electron correlated semiconductor FeSb₂

Author: Li, Huayao, Wang, Guohua, Ding, Ning, Ren, Quan, Zhao, Gan, Lin, Wenting, Yang, Jinchuan, Yan, Wensheng, Li, Qian, Yang, Run, Yuan, Shijun, Denlinger, Jonathan D., Wang, Zhenxing, Zhang, Xiaoqian, Wray, L. Andrew, Dong, Shuai, Qian, Dong, Miao, Lin

Issue&Volume: 2024-7-2

Abstract: Iron antimonide (FeSb₂) has been investigated for decades due to its puzzling electronic properties. It undergoes the temperature-controlled transition from an insulator to an ill-defined metal, with a cross-over from diamagnetism to paramagnetism. Extensive efforts have been made to uncover the underlying mechanism, but a consensus has yet to be reached. While macroscopic transport and magnetic measurements can be explained by different theoretical proposals, the essential spectroscopic evidence required to distinguish the physical origin is missing. In this paper, through the use of X-ray absorption spectroscopy and atomic multiplet simulations, we have observed the mixed spin states of 3d⁶ configuration in FeSb₂. Furthermore, we reveal that the enhancement of the conductivity, whether induced by temperature or doping, is characterized by populating the high-spin state from the low-spin state. Our work constitutes vital spectroscopic evidence that the electrical/magnetical transition in FeSb2 is directly associated with the spin-state excitation.

DOI: 10.1073/pnas.2321193121

Source: https://www.pnas.org/doi/abs/10.1073/pnas.2321193121