Antiferromagnetic ordering coupled with phonon mode anomalies in rare-earth cuprate NdCu2O4, probed by nuclear quadrupole resonance and raman spectroscopy

Shinji Wada, Hiroshi Sugiata, Daisuke Sawai, Takeshi Mito, Minoru Osada, Robert A. Fisher, Norman E. Phillips, Jeanne L. Luce, Angelica M. Stacy

Research output: Contribution to journalArticle

Abstract

We found evidence that two successive antiferromagnetic orderings of a rare earth cuprate NdCu2O4 (nonstandard monoclinic structure with magnetic Cu(1) and nonmagnetic Cu(2) sites) are strongly coupled with phonon mode anomalies. The nuclear quadrupole resonance frequency of 63,65Cu on the Cu(2) site shows a step decrease below each of the ordering temperatures TN1 ∼ 20 K and TN2 ∼ 10 K, that originates from changes in the symmetry of the charge distribution on the surrounding lattice. In the Raman spectrum, the shift of a phonon mode near 300 cm-1 displays an anomalous temperature dependence, which suggests a hardening of the lattice below TN1 and a softening below T N2. The Cu2+ spins on the Cu(1) site order antiferromagnetically below TN1, and the complex magnetic behavior is ascribed to the variations in the exchange interactions between the Cu(1) spins and in the paramagnetic spin polarization of Nd3+ below T N2.

Original languageEnglish
Pages (from-to)2076-2081
Number of pages6
JournalJournal of the Physical Society of Japan
Volume74
Issue number7
DOIs
Publication statusPublished - 2005 Jul
Externally publishedYes

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Keywords

  • Antiferromagnetic ordering
  • NdCuO
  • NMR
  • Phonon anomaly
  • Raman

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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