Current-Induced Metallization and Valence Transition in Black SmS

Abstract

A strongly-correlated insulator, samarium mono-sulfide (SmS), presents not only the pressure-induced insulator-to-metal transition (IMT) with the color change from black to golden-yellow but also current-induced IMT (CIMT) with negative resistance. To clarify the origin of the CIMT of SmS, the electronic structure change has been investigated by optical reflectivity and angle-integrated photoelectron spectra by applying an electric current. At lower temperatures than about 100 K, where the nonlinear $V$-$I$ curve has been observed, the carrier density rapidly increases, accompanied by decreasing relaxation time of carriers with increasing current. Then, the direct gap size increases, and the mean valence changes from Sm${}^{2+}$-dominant SmS to the mixed-valent one with increasing current. These results suggest that the CIMT originates from increasing the Sm $4f$-$5d$ hybridization intensity induced by the applied current.

arXiv commentMain text: 6 pages, 4 figures, Supplementary materials: 2 pages, 2 figures

References in corpus (5)

• Metal-insulator transitions: Influence of lattice structure, Jahn-Teller effect, and Hund's rule coupling
• Unified understanding of the valence transition in the rare-earth monochalcogenides under pressure
• Excitonic Instability in the Transition from the Black Phase to the Golden Phase of SmS under Pressure Investigated by Infrared Spectroscopy
• Interplay of Valence and Semimetal-to-Insulator Transitions in SmS
• Surface valence transition in SmS by alkali metal adsorption

Cited by in corpus (2)

• Photo-induced nonlinear band shift and valence transition in SmS
• Photo-induced phase transition on black samarium monosulfide