Magnetic excitations of CsFeCl3 in an external magnetic field parallel to the hexagonal plane
Magnetic excitations of CsFeCl3 in an external magnetic field parallel to the hexagonal plane
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CsFeCl3 在平行于六边形平面的外部磁场中的磁激发
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
M. Steiner
中科院分区：
文献类型：
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作者：
B. Schmid;B. Dorner;D. Petitgrand;L. Regnault;M. Steiner
在CsFeCl_3中，有效自旋为1的Fe ~（2+）离子局部具有单重基态（ms=0）。与各向异性相比，沿着方向的铁磁相互作用和垂直于它的反铁磁相互作用太弱，在没有外场的情况下不能引入长程有序。本文用中子非弹性散射方法研究了垂直于轴向外加高达6 T的外磁场中的激发谱。在零场中的初步测量表明，偶极效应导致色散曲线的最小值远离theK点的移动。我们发现，随着磁场的增加，整个色散片向更高的频率移动，出现分裂。借助忽略所有邻居之间的交换相互作用的局部哈密顿量，我们给出了依赖于磁场的磁激发强度的定性解释。一个更复杂的理论（RPA对角化的海森堡-哈密顿，用于描述的磁行为的CsFeCl 3）产量-除了在高能量转移的模式不匹配-一个令人满意的描述CsFeCl 3的磁激发依赖于磁场。
In CsFeCl3 the Fe2+-ion with effective spin one has locally a singlet ground state (ms=0). The ferromagnetic interactions along thec-direction and the anti-ferromagnetic interactions perpendicular to it are too week as compared to the anisotropy to introduce longrange order in the absence of an external field. By inelastic neutron scattering we have investigated the excitation spectrum in an external magnetic field up to 6 T applied perpendicular to thec-axis. Preliminary measurements in zero field show that dipolar effects lead to a shift of the minimum of the dispersion curve away from theK-point. We show that with increasing magnetic field the whole dispersion sheet is shifted towards higher frequencies and a splitting appears. With the help of a local Hamiltonian which neglects exchange interactions between all neighbours we give a qualitative explanation of the intensity of the magnetic excitations in dependence of the magnetic field. A more sophisticated theory (RPA-diagonalisation of the Heisenberg-Hamiltonian that is used to describe the magnetic behaviour of CsFeCl3) yields — apart from a mismatch for the modes at high energy transfers — a satisfactory description of the magnetic excitations of CsFeCl3 in dependence of the magnetic field.