µ-PES Studies on TiNCl and Quasi-two-dimensional Superconductor Na-intercalated TiNCl

Noriyuki Kataoka, Kensei Terashima, Masashi Tanaka, Wataru Hosoda, Takumi Taniguchi, Takanori Wakita, Yuji Muraoka, Takayoshi Yokoya

Research output: Contribution to journalArticle

Abstract

Electron-doped TiNCl is a superconductor, for which exotic mechanisms of the superconductivity have been discussed. However, difficulty in preparing large single-phase samples has prevented the direct observation of its electronic structure and how that changes with electron doping. In this study, micro-photoemission spectroscopy (µ-PES) was used to reveal the electronic structures of TiNCl and Na-intercalated TiNCl (Na-TiNCl). Comparison of Ti 2p core-level spectra shows the enhancement of a spectral feature in Na-TiNCl that suggests an increase in its metallic character. This indicates the introduction of electron carriers to the TiNCl layers. Although the overall valence band electronic structure of parent TiNCl could be reproduced by first-principle calculations, that of Na-TiNCl showed a marked deviation from the rigid band model near the Fermi level (EF). The spectral shape observed near EF of Na-TiNCl was found to be similar to a result in early transition metal oxides that has been attributed to the effect of strong electron correlation. The present study also demonstrated the usefulness of µ-PES to obtain reliable electronic structure data for samples that are difficult to make at large sizes.

Original languageEnglish
Article number104709
JournalJournal of the Physical Society of Japan
Volume88
Issue number10
DOIs
Publication statusPublished - Jan 1 2019

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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