Dynamical Bonding Driving Mixed Valency in a Metal Boride
- Univ. of California, Los Angeles, CA (United States); Columbia Univ., New York, NY (United States)
- Univ. of California, Los Angeles, CA (United States)
- Johns Hopkins Univ., Baltimore, MD (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Abstract Samarium hexaboride is an anomaly, having many exotic and seemingly mutually incompatible properties. It was proposed to be a mixed‐valent semiconductor, and later a topological Kondo insulator, and yet has a Fermi surface despite being an insulator. We propose a new and unified understanding of SmB 6 centered on the hitherto unrecognized dynamical bonding effect: the coexistence of two Sm−B bonding modes within SmB 6 , corresponding to different oxidation states of the Sm. The mixed valency arises in SmB 6 from thermal population of these distinct minima enabled by motion of B. Our model simultaneously explains the thermal valence fluctuations, appearance of magnetic Fermi surface, excess entropy at low temperatures, pressure‐induced phase transitions, and related features in Raman spectra and their unexpected dependence on temperature and boron isotope.
- Research Organization:
- Energy Frontier Research Centers (EFRC) (United States). Institute for Quantum Matter (IQM); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- 89233218CNA000001; SC0019331
- OSTI ID:
- 1671085
- Alternate ID(s):
- OSTI ID: 1608371
- Report Number(s):
- LA-UR-19-30421
- Journal Information:
- Angewandte Chemie (International Edition), Vol. 59, Issue 27; ISSN 1433-7851
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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