Yuan Yahua, Feng Hai L, Ghimire Madhav Prasad, Matsushita Yoshitaka, Tsujimoto Yoshihiro, He Jianfeng, Tanaka Masahiko, Katsuya Yoshio, Yamaura Kazunari
†Superconducting Properties Unit, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
‡Graduate School of Chemical Sciences and Engineering, Hokkaido University, North 10 West 8, Kita-ku, Sapporo, Hokkaido 060-0810, Japan.
Inorg Chem. 2015 Apr 6;54(7):3422-31. doi: 10.1021/ic503086a. Epub 2015 Mar 9.
Double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 have been synthesized under high-pressure and high-temperature conditions (6 GPa and 1500 °C). Their crystal structures and magnetic properties were studied by a synchrotron X-ray diffraction experiment and by magnetic susceptibility, specific heat, isothermal magnetization, and electrical resistivity measurements. Ca2MgOsO6 and Sr2MgOsO6 crystallized in monoclinic (P21/n) and tetragonal (I4/m) double-perovskite structures, respectively; the degree of order of the Os and Mg arrangement was 96% or higher. Although Ca2MgOsO6 and Sr2MgOsO6 are isoelectric, a magnetic-glass transition was observed for Ca2MgOsO6 at 19 K, while Sr2MgOsO6 showed an antiferromagnetic transition at 110 K. The antiferromagnetic-transition temperature is the highest in the family. A first-principles density functional approach revealed that Ca2MgOsO6 and Sr2MgOsO6 are likely to be antiferromagnetic Mott insulators in which the band gaps open, with Coulomb correlations of ∼1.8-3.0 eV. These compounds offer a better opportunity for the clarification of the basis of 5d magnetic sublattices, with regard to the possible use of perovskite-related oxides in multifunctional devices. The double-perovskite oxides Ca2MgOsO6 and Sr2MgOsO6 are likely to be Mott insulators with a magnetic-glass (MG) transition at ∼19 K and an antiferromagnetic (AFM) transition at ∼110 K, respectively. This AFM transition temperature is the highest among double-perovskite oxides containing single magnetic sublattices. Thus, these compounds offer valuable opportunities for studying the magnetic nature of 5d perovskite-related oxides, with regard to their possible use in multifunctional devices.
双钙钛矿氧化物Ca2MgOsO6和Sr2MgOsO6是在高压高温条件下（6吉帕斯卡和1500摄氏度）合成的。通过同步加速器X射线衍射实验以及磁化率、比热、等温磁化和电阻率测量对它们的晶体结构和磁性进行了研究。Ca2MgOsO6和Sr2MgOsO6分别结晶为单斜（P21/n）和四方（I4/m）双钙钛矿结构；Os和Mg排列的有序度为96%或更高。尽管Ca2MgOsO6和Sr2MgOsO6是等电子体，但在19 K时观察到Ca2MgOsO6发生磁玻璃转变，而Sr2MgOsO6在110 K时表现出反铁磁转变。该反铁磁转变温度在该族中是最高的。第一性原理密度泛函方法表明，Ca2MgOsO6和Sr2MgOsO6可能是反铁磁莫特绝缘体，其中带隙打开，库仑关联约为1.8 - 3.0电子伏特。就钙钛矿相关氧化物在多功能器件中的可能应用而言，这些化合物为阐明5d磁亚晶格的基础提供了更好的机会。双钙钛矿氧化物Ca2MgOsO6和Sr2MgOsO6可能分别是莫特绝缘体，在约19 K时发生磁玻璃（MG）转变，在约110 K时发生反铁磁（AFM）转变。该AFM转变温度在含单磁亚晶格的双钙钛矿氧化物中是最高的。因此，就它们在多功能器件中的可能应用而言，这些化合物为研究5d钙钛矿相关氧化物的磁性本质提供了有价值的机会。
