Specific heat of defects in Haldane systems Y2BaNiO5 and NENP: Absence of free spin-1/2 excitations

A. P. Ramirez, S. W. Cheong, M. L. Kaplan

Research output: Contribution to journalArticle

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Abstract

We have measured the specific heat of the antiferromagnetic spin-1 chain compounds NENP and Y2BaNiO5 diluted with Zn, at temperatures between 0.1 and 15 K and magnetic fields up to 9 T. We find that the defect-related Schottky anomaly in Y2BaNi1-xZnxO5 is better described by assuming the defects are S=1, rather than free S=1/2, the latter proposed to exist within the valence-bond-solid model of finite S=1 chains. The relationship of these results to electron-spin-resonance data for NENP, which imply free S=1/2 defects is discussed.

Original languageEnglish (US)
Pages (from-to)3108-3111
Number of pages4
JournalPhysical review letters
Volume72
Issue number19
DOIs
StatePublished - Jan 1 1994
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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