Persistent exchange splitting in the chiral helimagnet <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Cr</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>/</mml:mo><mml:mn>3</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>NbS</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>
Na Qin, Cheng Chen, Shiqiao Du, Xian Du, Xin Zhang, Zhongxu Yin, Jinsong Zhou, Runzhe Xu, Xu Gu, Qinqin Zhang, Wenxuan Zhao, Yidian Li, Sung‐Kwan Mo, Zhongkai Liu, Shilei Zhang, Yanfeng Guo, Peizhe Tang, Yulin Chen, Lexian Yang
Abstract
Using high-resolution angle-resolved photoemission spectroscopy and ab initio calculation, we systematically investigate the electronic structure of the chiral helimagnet ${\mathrm{Cr}}_{1/3}{\mathrm{NbS}}_{2}$ and its temperature evolution. The comparison with ${\mathrm{NbS}}_{2}$ suggests that the electronic structure of ${\mathrm{Cr}}_{1/3}{\mathrm{NbS}}_{2}$ is strongly modified by the intercalation of Cr atoms. Our ab initio calculation, consistent with experimental results, suggests strong hybridization between Nb- and Cr-derived states near the Fermi level. In the chiral helimagnetic state (below the Curie temperature, ${T}_{c}$), we observe exchange splitting of the energy bands crossing the Fermi level, which follows the temperature evolution of the magnetic moment, suggesting a strong interaction between the conduction electrons and Cr spin moments. Interestingly, the exchange splitting persists far above ${T}_{c}$ with weak temperature dependence, in drastic contrast to the itinerant ferromagnetism described by the Stoner model, indicating the existence of short-range magnetic order. Our results provide important insights into the interplay between the electronic structure and magnetism in ${\mathrm{Cr}}_{1/3}{\mathrm{NbS}}_{2}$, which is helpful for understanding the microscopic mechanism of chiral helimagnetic ordering.