Motion of the guest ion as precursor to the first-order phase transition in the cage system GdB 6

Kazuaki Iwasa, Ryosuke Igarashi, Kotaro Saito, Claire Laulhé, Toshihiko Orihara, Satoru Kunii, Keitaro Kuwahara, Hironori Nakao, Youichi Murakami, Fumitoshi Iga, Masafumi Sera, Satoshi Tsutsui, Hiroshi Uchiyama, Alfred Q.R. Baron

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

The motion of guest Gd ions in oversized boron cages in GdB 6 was investigated from phonon spectra measurements obtained by inelastic x-ray scattering. The measured phonon modes soften by about 10% from 300 K down to T N=16 K, in particular, the longitudinal phonon for the propagation vector q 1=(1/2,0,0) that characterizes the distorted structure below T N. Besides, the dispersion relation curves show kinklike anomalies at q k=(0.38,0.38,0). The observed results imply that the motion of the guest Gd ion interplays with the f electrons magnetoelastically and with carriers via Fermi surface nesting. The anomalous properties previously reported for this material far above T N originate from the strong electron-phonon coupling, which causes the motion of guest ions as precursors to the first-order phase transition.

Original languageEnglish
Article number214308
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number21
DOIs
Publication statusPublished - 2011 Dec 28

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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