2021/01/07 by Shinji Watanabe
Materials Science · Physics and Astronomy · #Band gap #Condensed matter physics #Iron-based superconductors research #Phase (matter) #Phase diagram #Phase transition #Physics #Physics of Superconductivity and Magnetism #Quantum critical point #Quantum mechanics #Quantum phase transition #Quantum phases #Rare-earth and actinide compounds #Semimetal #Superlattice #Valence (chemistry) #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.7566/jpsj.90.023706
published as J. Phys. Soc. Jpn. 90 (2021) 023706 · 5 pages, 5 figures
arxiv created 2021/01/07 · arxiv updated 2021/01/20 · openalex publication_date 2021/01/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Recent discoveries of a new type of quantum criticality arising from Yb-valence fluctuations in Yb-based metal in periodic crystal and quasicrystal have opened a new class of quantum critical phenomena in correlated electron systems. To clarify whether this new concept can be generalized to other rare-earth-based semimetal and insulator, we study SmS which exhibits golden-black phase transition under pressure. By constructing the model for SmS, we show that Coulomb repulsion between 4f and 5d orbitals at Sm drives first-order valence transition (FOVT) and semimetal-to-insulator transition (MIT) simultaneously, which explains the golden-black phase transition. We clarify the ground-state phase diagram for the FOVT and MIT by identifying the quantum critical point of the FOVT. We find that exciton condensates in both semimetal and insulator phases. Our result explains measured peak anomalies in the specific heat and compressibility in pressurized golden SmS and provides a cue to clarify recently-observed anomalies in black SmS.