Dani Sahil, Kumar Rakesh, Sharma Hitesh, Choudhary R J, Goyal Navdeep, Kaur Pawanpreet, Pandit Rabia
Department of Physics, Indian Institute of Technology, Roopnagar, 140001, Punjab, India.
Department of Physical Sciences, IKG Punjab Technical University, Kapurthala, 144603, Punjab, India.
Phys Chem Chem Phys. 2023 Aug 9;25(31):20863-20870. doi: 10.1039/d3cp02020g.
Thin films of double perovskite ruthenates, , BaDyRuO (BDRO) and SrDyRuO (SDRO), have been successfully grown on a SrTiO substrate using the pulsed laser deposition technique. The BDRO samples crystallizes in cubic structure, while SDRO exhibits monoclinic structure as revealed in their X-Ray diffraction examination. Temperature-dependent magnetization measurements suggest the presence of ferromagnetism in BDRO, while paramagnetism is present for the SDRO thin film. Surprisingly, both films show canted antiferromagnetism at ∼ = 5 K as revealed in their isothermal magnetization curves. The inverse susceptibility has been fitted to the Curie-Weiss law for the SDRO sample, where the Curie temperature ( ∼ -336.6 K) has been obtained, thus suggesting the prevalence of antiferromagnetic interactions. The existence of the canted magnetism at a lower temperature may be attributed to the Dzyaloshinskii-Moriya (D-M) interactions in the monoclinic SDRO sample due to structural distortion. However, the emergence of canted antiferromagnetism at lower temperatures (5 K) in the BDRO sample with cubic symmetry having no D-M interactions may be attributed to the various modifications at the surface of the thin films. Overall, a comparison made between the magnetic properties of both the thin films , BDRO & SDRO, reveals the suppression of bulk magnetic ordering when compared to their bulk counterparts. The possible reason for the absence of any magnetic ordering in these thin films may be due to any modifications in superexchange interactions, any exchange bias, stress-strain, or uncompensated spins present in these types of thin films. UV-visible measurements for both the samples reveal a direct influence of the A-site element (Sr/Ba) on their band gaps, , 3.66 eV and 2.59 eV for BDRO and SDRO samples, respectively, hence suggesting their insulating nature. We have also carried out first principles calculations with DFT using the CASTEP software to gain more insights into the experimental data. These thin films with insulating-antiferromagnetic properties may be crucial for "spintronics devices".
利用脉冲激光沉积技术，在SrTiO衬底上成功生长出了双钙钛矿钌酸盐薄膜，即BaDyRuO（BDRO）和SrDyRuO（SDRO）。BDRO样品呈立方结构结晶，而SDRO在X射线衍射检测中显示为单斜结构。与温度相关的磁化强度测量表明BDRO中存在铁磁性，而SDRO薄膜则呈现顺磁性。令人惊讶的是，等温磁化曲线显示，在约5 K时，两种薄膜均表现出倾斜反铁磁性。对于SDRO样品，其逆磁化率已根据居里 - 外斯定律进行拟合，由此得到居里温度（约 -336.6 K），这表明反铁磁相互作用占主导。低温下倾斜磁性的存在可能归因于单斜SDRO样品中由于结构畸变而产生的Dzyaloshinskii - Moriya（D - M）相互作用。然而，具有立方对称性且不存在D - M相互作用的BDRO样品在低温（5 K）下出现倾斜反铁磁性，可能归因于薄膜表面的各种改性。总体而言，对BDRO和SDRO这两种薄膜的磁性进行比较后发现，与它们的体相材料相比，体相磁有序受到了抑制。这些薄膜中不存在任何磁有序的可能原因，或许是由于这些类型的薄膜中，超交换相互作用、任何交换偏置、应力 - 应变或未补偿自旋发生了任何改变。对两个样品进行的紫外 - 可见测量表明，A位元素（Sr/Ba）对其带隙有直接影响，BDRO和SDRO样品的带隙分别为3.66 eV和2.59 eV，这表明它们具有绝缘性质。我们还使用CASTEP软件通过密度泛函理论（DFT）进行了第一性原理计算，以更深入地了解实验数据。这些具有绝缘 - 反铁磁性质的薄膜对于“自旋电子器件”可能至关重要。
