Statics and dynamics of incommensurate spin order in a geometrically frustrated antiferromagnet CdCr2O4 -: art. no. 247204
Statics and dynamics of incommensurate spin order in a geometrically frustrated antiferromagnet CdCr2O4 -: art. no. 247204
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DOI：
10.1103/physrevlett.95.247204
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发表时间：
2005-12-09
影响因子：
8.6
通讯作者：
Park, S
中科院分区：
文献类型：
--
作者：
Chung, JH;Matsuda, M;Park, S
用弹性和非弹性中子散射研究表明，立方尖晶石CdCr2O4在T-N=7.8K时，在类自旋-Peierls相变时发生沿c轴(c>；a=b)的伸长。Neel相(T<；T-N)具有无公度的自旋结构，特征波矢Q(M)=(0，β，1)，δ类似于0.09，自旋位于交流面上。这与另一种众所周知的铬基尖晶石--锌铬尖晶石形成了鲜明的对比，后者经历了c轴收缩和相应的自旋顺序。无公度Neel态的磁激发具有0.6 meV的弱各向异性带隙，它由至少三个带组成，最大可达5 meV。
Using elastic and inelastic neutron scattering we show that a cubic spinel, CdCr2O4, undergoes an elongation along the c axis (c > a=b) at its spin-Peierls-like phase transition at T-N=7.8 K. The Neel phase (T < T-N) has an incommensurate spin structure with a characteristic wave vector Q(M)=(0,delta,1) with delta similar to 0.09 and with spins lying on the ac plane. This is in stark contrast to another well-known Cr-based spinel, ZnCr2O4, that undergoes a c-axis contraction and a commensurate spin order. The magnetic excitation of the incommensurate Neel state has a weak anisotropy gap of 0.6 meV and it consists of at least three bands extending up to 5 meV.