SPECIFIC-HEAT OF DEFECTS IN HALDANE SYSTEMS Y2BANIO5 AND NENP - ABSENCE OF FREE SPIN-1/2 EXCITATIONS

被引：80

作者：

RAMIREZ, AP

CHEONG, SW

KAPLAN, ML

机构：

[1] AT and T Bell Laboratories, Murray Hill, NJ 07974

来源：

PHYSICAL REVIEW LETTERS | 1994年 / 72卷 / 19期

关键词：

D O I：

10.1103/PhysRevLett.72.3108

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

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.

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页码：3108 / 3111

页数：4

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