论文标题
地面结构，轨道订购和金属绝缘体过渡中的双层晶矿prbamn2O6
Ground-state structure, orbital ordering and metal-insulator transition in double-perovskite PrBaMn2O6
论文作者
论文摘要
近年来，A站点订购的半掺杂双栖息地锰米甘油甘蓝米$ \ rm rbamn_2o_6 $（r =稀土）由于其出色的物理特性以及将其作为磁性，多肉毒和氧气存储材料而引起了很大的关注。 $ {\ rm rmn_2o_6} $中基态的性质以及冷却时进行的相变序列尚未得到充分理解，这是由于实验和理论研究的复杂性。在这里，我们解决了Prbamn $ _2 $ o $ $ _6 $的基础结构的起源以及其电子和磁性。利用GGA+U方法和专门设计的策略来执行结构优化，我们表明该系统具有两个竞争性的AFM-A和AFM-CE磁性结构，具有非常紧密的能量。 AFM-A结构是一种金属，而AFM-CE是绝缘子，向绝缘状态的过渡伴随着电荷Mn $^{3+} $/Mn $^{4+} $，而轨道$ 3X^2-r^2 r^2 $/$ 3Y^2 $ 3Y^2-r^2-r^2 r^2 $订购。这种轨道排序会导致强大的合作Jahn-Teller（JT）扭曲，从而降低了晶体对称性。我们的发现为理解$ {\ rm prbamn_2o_6} $的可用实验数据中的矛盾提供了关键，并为其他$ {\ rm rm rbamn_2o_6} $化合物中地面结构的理论改进开辟了前景。
In recent years, A-site ordered half-doped double-perovskite manganites $\rm RBaMn_2O_6$ (R=rare earth) have attracted much attention due to their remarkable physical properties and a prospect of application as magnetoresistance, multiferroic, and oxygen storage materials. The nature of the ground state in ${\rm RBaMn_2O_6}$ as well as sequence of phase transitions taking place at cooling are not yet well understood due to complexity in both experimental and theoretical studies. Here we address the origin of the ground-state structure in PrBaMn$_2$O$_6$ as well as its electronic and magnetic properties. Utilizing GGA+U approach and specially designed strategy to perform structural optimization, we show that the system has two competing AFM-A and AFM-CE magnetic structures with very close energies. The AFM-A structure is a metal, while AFM-CE is an insulator and the transition to the insulating state is accompanied by the charge Mn$^{3+}$/Mn$^{4+}$, and orbital $3x^2-r^2$/$3y^2-r^2$ orderings. This orbital ordering results in strong cooperative Jahn-Teller (JT) distortions, which lower the crystal symmetry. Our findings give a key to understanding contradictions in available experimental data on ${\rm PrBaMn_2O_6}$ and opens up the prospects to theoretical refinements of ground-state structures in other ${\rm RBaMn_2O_6}$ compounds.
