Korringa factor in Dirac-nodal-line systems

Abstract

The Korringa factor K(α) in the nuclear magnetic resonance studies is a widely used measure of electron-correlation effects in metals and is conventionally interpreted using the non-correlated value K(α) = 1. In Dirac-fermion systems, however, the non-correlated reference value depends on the electronic density of states (DOS) and differs from that of conventional metals. Here, we theoretically investigate the non-correlated Korringa factor K^*(α) in a Dirac nodal-line (DNL) system with finite nodal-line dispersion using a DOS-based approach. We show that K^*(α) exhibits an intrinsic temperature dependence, continuously evolving from the Dirac-fermion value of 1.71 at high temperatures to the metallic value of 1 at low temperatures. The crossover temperature is found to be proportional to the nodal-line dispersion width, identified as the characteristic energy scale governing the non-correlated Korringa factor in DNL systems. We further demonstrate that Landau quantization generates singular DOS structures that strongly enhance K^*(α), producing pronounced peaks even in the absence of electron correlations. In addition, K^*(α) exhibits two distinct types of magnetic oscillations arising from intra-level and inter-level contributions. The latter originates from the overlap of singular points belonging to positive and negative quantum-number Landau subbands at the Fermi level and represents a unique consequence of the finite energy dispersion of a DNL. These results provide a quantitative reference for interpreting NMR experiments in DNL materials and for identifying genuine correlation effects beyond DOS-induced contributions.

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Cite

BibTeX RIS

BibTeX

@misc{sekine2026korringa,
  title = {{Korringa factor in Dirac-nodal-line systems}},
  author = {Takahiko Sekine and Kanoda Kazushi},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.03994},
  eprint = {2611.03994},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.03994},
}

RIS

TY  - UNPB
TI  - Korringa factor in Dirac-nodal-line systems
AU  - Takahiko Sekine
AU  - Kanoda Kazushi
PY  - 2026
DA  - 2026/11/02
PB  - arXiv
DO  - 10.48550/arxiv.2611.03994
UR  - https://arxiv.org/abs/2611.03994
AB  - The Korringa factor K(α) in the nuclear magnetic resonance studies is a widely used measure of electron-correlation effects in metals and is conventionally interpreted using the non-correlated value K(α) = 1. In Dirac-fermion systems, however, the non-correlated reference value depends on the electronic density of states (DOS) and differs from that of conventional metals. Here, we theoretically investigate the non-correlated Korringa factor K^*(α) in a Dirac nodal-line (DNL) system with finite nodal-line dispersion using a DOS-based approach. We show that K^*(α) exhibits an intrinsic temperature dependence, continuously evolving from the Dirac-fermion value of 1.71 at high temperatures to the metallic value of 1 at low temperatures. The crossover temperature is found to be proportional to the nodal-line dispersion width, identified as the characteristic energy scale governing the non-correlated Korringa factor in DNL systems. We further demonstrate that Landau quantization generates singular DOS structures that strongly enhance K^*(α), producing pronounced peaks even in the absence of electron correlations. In addition, K^*(α) exhibits two distinct types of magnetic oscillations arising from intra-level and inter-level contributions. The latter originates from the overlap of singular points belonging to positive and negative quantum-number Landau subbands at the Fermi level and represents a unique consequence of the finite energy dispersion of a DNL. These results provide a quantitative reference for interpreting NMR experiments in DNL materials and for identifying genuine correlation effects beyond DOS-induced contributions.
ER  -

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