Role of magnetic and structural symmetry breaking in forming the Mott insulating gap in Nb3Cl8
Journal Article
·
· Physical Review. B
- Univ. of Colorado, Boulder, CO (United States); Renewable and Sustainable Energy Institute, University of Colorado Boulder
- Univ. of Colorado, Boulder, CO (United States)
The α-phase of the gapped insulator Nb3Cl8 has recently emerged as the long-sought critical testing bed for examining the importance of strong interelectronic correlation vs symmetry breaking in understanding insulation of such Mott compounds. Structural symmetry breaking detected by density functional theory (DFT) energy lowering (such as dimer formation, disproportionation, or Jahn-Teller distortions) explains insulation in both d-electron Mott-like systems and in non-d-electron cases without recourse to strong correlation. Yet, in Nb3Cl8, structural symmetry breaking alone (viz. formation of Nb trimers) fails to explain insulation, leading instead to a partially occupied metallic flat band, in contrast with experimental observations. We examine the role of magnetic symmetry breaking, noting that Nb3Cl8 is an observed paramagnet (not an antiferromagnet), thus potentially carrying also short-range ordered magnetic moments. Describing the latter as a polymorphous distribution of nonzero local moments with total zero net magnetization is demonstrated to lower the DFT total energy, while gapping the system without recourse to strong correlation or long-range magnetic order. This suggests that degeneracy removal by symmetry breaking in mean-field-like approaches—either structural, or magnetic, or both—can reduce or eliminate the need for strong correlation, allowing the use of DFT for such Mott systems.
- Research Organization:
- Univ. of Colorado, Boulder, CO (United States); Univ. of Colorado, Boulder, CO (United States). Renewable and Sustainable Energy Institute (RSEI)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
- Grant/Contract Number:
- SC0010467
- OSTI ID:
- 2555843
- Alternate ID(s):
- OSTI ID: 2556928
OSTI ID: 3012045
- Journal Information:
- Physical Review. B, Journal Name: Physical Review. B Journal Issue: 15 Vol. 111; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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