Uncovering orbital liquid behaviour in a nitrite perovskite

Orbital ordering is responsible for many key physical properties including magnetism, colossal magnetoresistance and battery cathode resilience. The ordering transitions of Jahn-Teller distortions typically occur at high temperatures due to the large local strains. In this proposal (which pairs HRPD & POLARIS proposals), we will investigate a perovskite structured material in which the Co(II) orbital ordered is greatly suppressed: suggesting that there is an orbital liquid phase without any site disorder. We will use POLARIS to monitor the orbital liquid phase using total scattering and HRPD to measure the ordered phase and average structure to produce a complete picture of this.

轨道有序（Orbital ordering）是诸多关键物理性质的根源，包括磁性、巨磁电阻及电池正极的稳定性。由于局部应变较大，姜-泰勒畸变（Jahn-Teller distortions）的有序转变通常发生在高温条件下。本提案（结合HRPD与POLARIS提案）将研究一种钙钛矿结构材料，其Co(II)轨道有序被显著抑制——这暗示存在无任何位点无序的轨道液相（orbital liquid phase）。我们将利用POLARIS通过全散射监测轨道液相，并借助HRPD测量有序相及平均结构，以完整描绘这一现象。