Pradhan Suman Kalyan, Dalal Biswajit, Kumar Ravi, Majumdar Subham, De Subodh Kumar
School of Materials Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata 700 032, India.
J Phys Condens Matter. 2020 Jul 15;32(30):305803. doi: 10.1088/1361-648X/ab832e. Epub 2020 Mar 25.
LaCuIrO is a spin-orbit coupled Mott insulator, and shows a transition to noncollinear antiferromagnetic state from paramagnetic state below 74 K, and further into a weak ferromagnetic state below 54 K. Despite having two different magnetic phases, the LaCuIrO compound does not exhibit exchange bias phenomenon. In this present work, we report an experimental investigation on the structural and magnetic properties of the double perovskite compound LaCuCrIrO through high-resolution synchrotron x-ray diffraction, x-ray absorption near edge structure (XANES), and temperature and field-dependent magnetization measurements. Powder x-ray diffraction analysis reveals that the sample crystallizes in triclinic structure (space group P [Formula: see text]) alike parent LaCuIrO compound, while XANES measurements rule out the possibility of valence state alteration between constituting elements in this sample. Interestingly, LaCuCrIrO compound is found to exhibit ferromagnetic cluster glass behavior, where field-cooled magnetization undergoes two ferromagnetic transitions. A significant enhancement of ferromagnetic component is also evident from hysteresis loop study, which is likely associated with the electron hopping between J = 1/2 pseudospin state of Ir ions and empty e-orbital of Cr ions. Exclusively, this Cr-doped compound exhibits exchange bias effect, which is related to the complex interfacial exchange coupling between the ferromagnetic clusters and the host antiferromagnetic matrix.
LaCuIrO是一种自旋轨道耦合莫特绝缘体，在74K以下从顺磁态转变为非共线反铁磁态，并在54K以下进一步转变为弱铁磁态。尽管具有两种不同的磁相，但LaCuIrO化合物并未表现出交换偏置现象。在本工作中，我们通过高分辨率同步辐射X射线衍射、X射线吸收近边结构（XANES）以及温度和磁场依赖的磁化测量，报告了对双钙钛矿化合物LaCuCrIrO的结构和磁性能的实验研究。粉末X射线衍射分析表明，该样品与母体LaCuIrO化合物一样，结晶为三斜结构（空间群P [公式：见原文]），而XANES测量排除了该样品中构成元素之间价态改变的可能性。有趣的是，发现LaCuCrIrO化合物表现出铁磁团簇玻璃行为，其中场冷磁化经历两次铁磁转变。磁滞回线研究也明显显示出铁磁成分的显著增强，这可能与Ir离子的J = 1/2赝自旋态与Cr离子的空e轨道之间的电子跳跃有关。特别地，这种Cr掺杂化合物表现出交换偏置效应，这与铁磁团簇与主体反铁磁基质之间复杂的界面交换耦合有关。
