标题： $3d$-电子海森堡金红石锰$_2$锑$_2$氧$_7$ 显示英文标题

标题： The $3d$-Electron Heisenberg Pyrochlore Mn$_2$Sb$_2$O$_7$

摘要： 在受挫的磁性系统中，几何约束或相互作用之间的竞争引入了极高的简并性，并阻止系统轻易选择低温基态。 已知最受挫的自旋排列出现在尖晶石结构晶格上，但几乎所有的磁性尖晶石结构都具有未淬灭的轨道角动量，通过自旋-轨道耦合限制自旋方向。 尖晶石结构Mn$_2$Sb$_2$O$_7$是一种极其罕见的海森堡尖晶石结构系统，其自旋方向不受限制且化学无序程度低。 我们表明它在5.5K时发生自旋玻璃转变，这种转变会被由于Mn空位产生的无序所抑制，表明该基态是自旋相互作用的直接结果。 与具有未淬灭角动量的$3d$过渡金属尖晶石结构的显著相似性表明，$3d$块中的低自旋-轨道耦合使得海森堡尖晶石结构比之前想象的更容易获得。 显示英文摘要

摘要： In frustrated magnetic systems, geometric constraints or the competition amongst interactions introduce extremely high degeneracy and prevent the system from readily selecting a low-temperature ground state. The most frustrated known spin arrangement is on the pyrochlore lattice, but nearly all magnetic pyrochlores have unquenched orbital angular momentum, constraining the spin directions through spin-orbit coupling. Pyrochlore Mn$_2$Sb$_2$O$_7$ is an extremely rare Heisenberg pyrochlore system, with directionally-unconstrained spins and low chemical disorder. We show that it undergoes a spin-glass transition at 5.5K, which is suppressed by disorder arising from Mn vacancies, indicating this ground state to be a direct consequence of the spins' interactions. The striking similarities to $3d$ transition metal pyrochlores with unquenched angular momentum suggests that the low spin-orbit coupling in the $3d$ block makes Heisenberg pyrochlores far more accessible than previously imagined.