THEORY OF SPIN REORIENTATION IN RARE-EARTH ORTHOCHROMITES AND ORTHOFERRITES
THEORY OF SPIN REORIENTATION IN RARE-EARTH ORTHOCHROMITES AND ORTHOFERRITES
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DOI：
10.1016/s0022-3697(74)80003-x
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发表时间：
1974-01-01
影响因子：
4
通讯作者：
YAMAGUCHI, T
中科院分区：
文献类型：
--
作者：
YAMAGUCHI, T
研究了稀土正铬铁矿（和正铁氧体）中温度诱导自旋重取向的机理。结果表明，Cr3+（或Fe3+）与稀土离子之间的磁相互作用的各向异性部分，即反对称和各向异性-对称交换相互作用，通常是自旋取向的旋转型和突变型的原因。这些各向异性交换相互作用产生了垂直于这些自旋方向的Cr3+向上自旋的有效场，以及与上述方向相反的Cr3+向下自旋的有效场。这些有效的场有利于Cr3+自旋的旋转，保持了它们原来的反铁磁结构。因此，随着温度的降低，由于稀土磁化强度的增加，该有效场增大，当Cr3+自旋与这些有效场的相互作用能超过Cr3+离子的各向异性能时，发生自旋重取向。发生。在自旋取向的开始和结束处发生了二阶相变。强调了突变自旋重定向的一阶性质。Cr3+与稀土离子之间的各向异性交换作用在诱导突变自旋重取向中也起着重要作用。
Mechanisms of the temperature-induced spin-reorientation in rare-earth orthochromites (and orthoferrites) are examined. It is concluded that the anisotropic parts of the magnetic interactions between Cr3+(or Fe3+) and rare-earth ions, the antisymmetric and the anisotropic-symmetric exchange interactions, are generally responsible for both therotationaland theabrupttypes of the spin-reorientations. These anisotropic exchange interactions produce an effective field for the Cr3+up-spins in the direction perpendicular to that of these spins and an effective field for the Cr3+down-spins in the direction opposite to the above. These effective fields favor rotation of the Cr3+spins, retaining their original antiferromagnetic configuration. Thus, as the temperature is lowered, this effective field increases due to the increase of the rare-earth magnetization, and when the interaction energy of the Cr3+spins with these effective fields exceeds the anisotropy energy of the Cr3+ion, spin-reorientation. takes place. At the beginning and ending of the spin-reorientation a second-order phase-transition occurs. The first-order nature of theabruptspin-reorientation is stressed. Anisotropic exchange interactions between Cr3+and rare-earth ions also play an important role in inducing theabruptspin-reorientation.