Temperature evolution of magnetic and transport behavior in 5d Mott insulator Sr2IrO4: significance of magneto-structural coupling
Temperature evolution of magnetic and transport behavior in 5d Mott insulator Sr2IrO4: significance of magneto-structural coupling
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DOI：
10.1088/0953-8984/27/1/016005
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发表时间：
2015-01-14
影响因子：
2.7
通讯作者：
Pramanik, A. K.
中科院分区：
文献类型：
--
作者：
Bhatti, Imtiaz Noor;Rawat, R.;Pramanik, A. K.
我们研究了钙钛矿型层状化合物Sr_2IrO_4的磁性随温度的演化及其与结构参数的相互关系，该化合物被认为是J（eff）= 1/2的Mott绝缘体。结构畸变在这种材料中起着重要的作用，并在反铁磁有序的磁性状态下诱导弱铁磁性，其转变温度约为240 K。有趣的是，在低于100 K的低温下，已经观察到磁矩的变化。温度依赖的X射线衍射测量表明，结构参数在100 K左右的突然变化是负责这一点。电阻率测量显示在整个温度范围内的磁性相变的绝缘行为。电子输运可以用Mott的二维变程跳跃（VRH）机制来描述，然而，VRH存在三个不同的温度范围，这是局域长度随温度变化的结果。与通常在强自旋轨道耦合材料中观察到的正行为相反，在所有温度下都观察到负磁阻（MR）。MR的二次场依赖性意味着量子干涉效应的相关性。
We have investigated the temperature evolution of magnetism and its interrelation with structural parameters in the perovskite-based layered compound Sr2IrO4, which is believed to be a J(eff) = 1/2 Mott insulator. The structural distortion plays an important role in this material and induces a weak ferromagnetism in an otherwise antiferromagnetically ordered magnetic state with a transition temperature around 240 K. Interestingly, at low temperatures, below around 100 K, a change in the magnetic moment has been observed. Temperature dependent x-ray diffraction measurements show that sudden changes in structural parameters around 100 K are responsible for this. Resistivity measurements show insulating behavior throughout the temperature range across the magnetic phase transition. The electronic transport can be described with Mott's two-dimensional variable range hopping (VRH) mechanism, however, three different temperature ranges are found for VRH, which is a result of varying the localization length with temperature. A negative magnetoresistance (MR) has been observed at all temperatures in contrast to positive behavior generally observed in strongly spin-orbit coupled materials. The quadratic field dependence of MR implies the relevance of a quantum interference effect.