Structure and Magnetic Order in Mn2NiReO6 - an ‘All Transition Metal’ double perovskite

A2BB’O6 double perovskites are an important family of materials, with spintronic properties found in some examples e.g. Sr2FeMoO6. Although A2+ sites are usually occupied by non-magnetic cations such as Ca, Sr, Ba, recent work has shown that Mn2+ can be introduced using high pressures to create ‘All Transition Metal’ double perovskites where all cation sites are occupied by magnetic transition metal ions. We have recently prepared Mn2NiReO6 which has a monoclinically distorted P21/n double perovskite structure and a ferro/ferri- magnetic transition at 100 K. One day of beamtime at WISH is requested to determine the accurate crystal structure, where the neutron scattering length contrast of Mn, Ni and Re (-3.73, 10.3 and 9.2 fm, respectively) will detect any A/B site disorder and O-positions will give accurate octahedral tilt angles, and the magnetic order of the 3 spin sublattices.

A₂BB'O₆型双钙钛矿（double perovskites）是一类重要的功能材料体系，部分成员展现出自旋电子学（spintronics）特性，例如Sr₂FeMoO₆。尽管A²+位点通常由Ca、Sr、Ba等非磁性阳离子占据，但近期研究证实，可通过高压手段引入Mn²+，制备得到“全过渡金属”双钙钛矿——该类材料的所有阳离子位点均由磁性过渡金属离子占据。我们近期成功制备出Mn₂NiReO₆，其具有单斜畸变的P2₁/n型双钙钛矿结构，并在100 K温度下发生铁/亚铁磁转变。本次申请使用WISH谱仪1天的束流时间，用于精准测定其晶体结构：Mn、Ni、Re的中子散射长度对比度分别为-3.73、10.3与9.2 fm（飞米，femtometer），可有效检测A/B位的原子无序情况；通过氧原子的位置信息可精准得到八面体倾斜角，同时解析三个自旋亚晶格的磁有序结构。