Direct observation of field-induced incommensurate fluctuations in a one-dimensional S=1/2 antiferromagnet
Direct observation of field-induced incommensurate fluctuations in a one-dimensional S=1/2 antiferromagnet
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DOI：
10.1103/physrevlett.79.1750
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发表时间：
1997-09-01
影响因子：
8.6
通讯作者：
Aeppli, G
中科院分区：
文献类型：
--
作者：
Dender, DC;Hammar, PR;Aeppli, G
苯甲酸铜(C6D5COO)的中子散射(2)3D(2)O，首次提供了一维自旋S=1/2反铁磁体中依赖于场的无公度低能模的直接实验证据。如Bethe ansatz和S=1/2链的自旋描述所预言的那样，波矢(Q)在波矢(Q)上=pi+/-增量(Q)在波纹(H)上出现软模，其中波矢(Q)在波纹(H)上的波矢(Q)近似为2pi M(H)/gMu(B)。意想不到的是场诱导的能隙增量(H)αH-α，其中α=0.65(3)，由比热测量确定。在H=7T(gMu(B)H/J=0.52)时，能隙的大小随外场方向的不同从0.06J变化到0.3J。
Neutron scattering from copper benzoate, Cu(C6D5COO)(2) . 3D(2)O, provides the first direct experimental evidence for field-dependent incommensurate low energy modes in a one-dimensional spin S = 1/2 antiferromagnet. Soft modes occur for wave vectors (q) over tilde = pi +/- delta (q) over tilde(H), where delta (q) over tilde(H) approximate to 2 pi M(H)/g mu(B) as predicted by Bethe ansatz and spinon descriptions of the S = 1/2 chain. Unexpected was a field-induced energy gap Delta(H) alpha H-alpha, where alpha = 0.65(3) as determined from specific heat measurements. At H = 7 T (g mu(B)H/J = 0.52), the magnitude of the gap varies from 0.06J to 0.3J depending on the orientation of the applied field.