Unique Band Structure of Pressure Induced Semiconducting State in SmS Characterized by 33S-Nuclear Magnetic Resonance Measurements

• Published in: Journal of the Physical Society of Japan 2024-01, Vol.93 (1), p.1
• Main Authors: Yoshida, Shogo, Ueda, Hajime, Mutou, Tetsuya, Katakami, Shun, Okada, Masato, Yokoyama, Yuichi, Mizumaki, Masaichiro, Hiraoka, Naoka, Kitagawa, Kentaro, Haga, Yoshinori, Fujii, Takuto, Nakai, Yusuke, Mito, Takeshi
• Format: Article
• Language: eng ; jpn
• Subjects: Band structure of solids; Bayesian analysis; Conduction electrons; Elementary excitations; Energy gap; High pressure; Low temperature; NMR; Nuclear magnetic resonance; Nuclear spin; Relaxation time; Spin-lattice relaxation; Statistical inference; Temperature dependence
• ISSN: 0031-9015; 1347-4073
• DOI: 10.7566/JPSJ.93.013702

In Kondo insulators, where a small energy gap evolves only at low temperatures, it is challenging to experimentally clarify their electronic structures, especially under high pressure. In this study, we have carried out high-pressure 33S-nuclear magnetic resonance measurements on a pressure-induced semiconducting phase with a small energy gap of SmS. To analyze the recovery curve of nuclear spin–lattice relaxation time T1, consisting of multiple components, the Bayesian inference was introduced. The unique temperature dependence of 1/T1 is reproduced based on a simplified rectangular band model and a periodic Anderson model, which allows to obtain parameters characterizing the semiconducting state semi-quantitatively: the bandwidths of conduction electrons and quasiparticles are much narrower and the energy gap is smaller than for SmB6, a prototypical Kondo insulator. This peculiar band structure in the small gap state may arise from the characteristics of weak correlations and relatively strong hybridization.