Metamagnetic transition in EuFe2As2 single crystals
Metamagnetic transition in EuFe2As2 single crystals
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DOI：
10.1088/1367-2630/11/2/025007
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发表时间：
2009-02-27
影响因子：
3.3
通讯作者：
Xu, Zhu'an
中科院分区：
文献类型：
--
作者：
Jiang, Shuai;Luo, Yongkang;Xu, Zhu'an
本文报道了砷化铁高温超导体母体化合物EuFe_2As_2单晶的各向异性磁化强度和磁电阻的测量结果。除了在186 K发生的与Fe磁矩有关的反铁磁（AFM）自旋密度波（SDW）相变外，该化合物在19 K还发生了另一个由于Eu ~（2+）自旋的AFM有序化（J = S = 7/2）而引起的磁性相变。后者的AFM状态下的磁场表现出变磁（MM）转变。当在2 K下施加H平行于c的磁场时，磁化强度线性增加到7.0 μ（B）f. u。(-1)在μ H-0 = 1.7 T，然后保持在这个值的饱和Eu 2+的时刻在更高的领域。在H平行于ab的情况下，磁化强度呈阶梯状增加到6.6 μ（B）f.u（-1），磁滞很小。用4.4 μ（B）f. u的饱和矩鉴定MM相。（-1）。MM转变伴随着负的面内MR，反映了Eu 2+磁矩有序化对FeAs层导电性的影响。这些结果解释了自旋重取向和自旋反转的基础上的A型原子力显微镜结构的Eu 2+自旋。建立了磁相图。
We report the measurements of the anisotropic magnetization and magnetoresistance (MR) on single crystals of EuFe2As2, a parent compound of ferro-arsenide high-temperature superconductor. Apart from the antiferromagnetic (AFM) spin density wave (SDW) transition at 186K associated with Fe moments, the compound undergoes another magnetic phase transition at 19K due to AFM ordering of Eu2+ spins (J = S = 7/2). The latter AFM state exhibits metamagnetic (MM) transition under magnetic fields. Upon applying magnetic field with H parallel to c at 2 K, the magnetization increases linearly to 7.0 mu(B) f.u.(-1) at mu H-0 = 1.7 T and then remains at this value for saturated Eu2+ moments under higher fields. In the case of H parallel to ab, the magnetization increases step-like to 6.6 mu(B) f.u(-1) with small magnetic hysteresis. An MM phase was identified with the saturated moments of 4.4 mu(B) f.u.(-1). The MM transition accompanies negative in-plane MR, reflecting the influence of Eu2+ moments ordering on the electrical conduction of FeAs layers. These results were explained in terms of spin-reorientation and spin-reversal based on an A-type AFM structure for Eu2+ spins. The magnetic phase diagram has been established.