Spiral phase and spin waves in the quasi-two-dimensional antiferromagnet Ba2CuGe2O7

被引:61
作者
Zheludev, A [1 ]
Shirane, G [1 ]
Sasago, Y [1 ]
Kiode, N [1 ]
Uchinokura, K [1 ]
机构
[1] UNIV TOKYO,DEPT APPL PHYS,BUNKYO KU,TOKYO 113,JAPAN
来源
PHYSICAL REVIEW B | 1996年 / 54卷 / 21期
关键词
D O I
10.1103/PhysRevB.54.15163
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The quasi-two-dimensional square-lattice antiferromagnet Ba2CuGe2O7 was studied by neutron scattering and bulk magnetic techniques. An incommensurate magnetic spiral structure with the propagation vector (1+zeta,1+zeta,0) (lambda = 0.027) was observed below T-N = 3.26 K. Magnetic ordering occurs with a two-dimensional-like critical exponent beta approximate to 0.15. The spin dynamics can be adequately described by conventional spin-wave theory with two exchange constants: nearest-neighbor in-plane antiferromagnetic coupling J(1) approximate to 0.48 meV and interplane ferromagnetic interaction J(perpendicular to) approximate to 0.013 meV. This set of exchange parameters apparently fails to explain the spiral order. The noncentrosymmetric crystal structure suggests that the incommensurate phase may be the result of a Dzyaloshinskii-Moriya instability of the Neel ground state.
引用
收藏
页码:15163 / 15170
页数:8
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