Local observations of orbital diamagnetism and excitation in three-dimensional dirac fermion systems Bi1-xSbx

Yukihiro Watanabe, Masashi Kumazaki, Hiroki Ezure, Takao Sasagawa, Robert Cava, Masayuki Itoh, Yasuhiro Shimizu

Research output: Contribution to journalArticlepeer-review

Abstract

Dirac fermions display a singular response against magnetic and electric fields. A distinct manifestation is the large diamagnetism originating in the interband effect of Bloch bands, as observed in bismuth alloys. Through 209Bi NMR spectroscopy, we extract diamagnetic orbital susceptibility inherent to Dirac fermions in the semiconducting bismuth alloys Bi1-xSbx(x = 0.08-0.16). The 209Bi hyperfine coupling constant provides an estimate of the effective orbital radius. In addition to the interband diamagnetism, the NMR shift includes an anomalous temperature-independent term originating in the enhanced intraband diamagnetism under strong spin-orbit coupling. The nuclear spin-lattice relaxation rate 1=T1 is dominated by orbital excitation and follows cubic temperature dependence in an extensive temperature range. The result demonstrates the robust diamagnetism and low-lying orbital excitation against the small gap opening, whereas x-dependent spin excitation appears at low temperatures.

Original languageEnglish (US)
Article number053701
JournalJournal of the Physical Society of Japan
Volume90
Issue number5
DOIs
StatePublished - Apr 2 2021

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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