Studies of 27Al NMR in SrAl4

Haruo Niki, Nonoka Higa, Hiroko Kuroshima, Tatsuki Toji, Mach Morishima, Motofumi Minei, Mamoru Yogi, Ai Nakamura, Masato Hedo, Takao Nakama, Yoshichika Onuki, Hisatomo Harima

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)

Abstract

A charge density wave (CDW) transition at TCDW = 243 K and a structural phase (SP) transition at approximately 100 K occur in SrAl4 with the BaAl4-type body center tetragonal structure, which is the divalent and non-4f electron reference compound of EuAl4. To understand the behaviors of the CDW and SP transitions, the 27Al NMR measurements using a single crystal and a powder sample of SrAl4 have been carried out. The line width below TCDW is modulated by an electrical quadruple interaction between 27Al nucleus and CDW charge modulation. The incommensurate CDW state below TCDW changes into a different structure below TSP. The temperature dependences of Knight shifts of 27Al(I) and 27Al(II) show the different behaviors. The temperature variation of 27Al(I) Knight shift shows anomalies at the CDW and SP transition temperatures, revealing the shift to negative side below TCDW, which is attributable to the core polarization of the d-electrons. However, 27Al(II) Knight shift keeps almost constant except for the small shift due to the SP transition. The 1/T1T of 27Al(I) indicates the obvious changes due to the CDW and SP transitions, while that of 27Al(II) takes a constant value. The density of state at the Fermi level at Al(I) site below 60 K would be about 0.9 times less than that above TCDW.

Original languageEnglish
Pages (from-to)763-770
Number of pages8
JournalPhysics Procedia
Volume75
DOIs
Publication statusPublished - 2015
Externally publishedYes
Event20th International Conference on Magnetism, ICM 2015 - Barcelona, Spain
Duration: 2015 Jul 52015 Jul 10

Keywords

  • Knight shift
  • NMR
  • SrAl
  • charge density wave
  • spin-lattice relaxation time
  • structural phase transition

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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