Single phase charge ordered stoichiometric CaFe3O5 with commensurate and incommensurate trimeron ordering
Single phase charge ordered stoichiometric CaFe3O5 with commensurate and incommensurate trimeron ordering
复制标题
DOI：
10.1038/s41467-019-13450-5
复制
发表时间：
2019-12-02
影响因子：
16.6
通讯作者：
Clarke, Simon J.
中科院分区：
文献类型：
--
作者：
Cassidy, Simon J.;Orlandi, Fabio;Clarke, Simon J.
混合价过渡金属化合物显示出复杂的结构、电子和磁性能，这些能经常被精细地调谐。本文采用中子粉末衍射、蒙特卡罗模拟和对称性分析等方法对化学计量CaFe3O5的电荷有序态进行了探测。磁有序是由铁磁性Fe3+-Fe2+-Fe3+三聚体的形成所主导的，这些三聚体在磁有序转变上很明显。在T-N= 289 K和281 K之间，由于磁挫折产生了不相称的磁有序相，但自旋扬-泰勒畸变解除了这种挫折，使磁有序在较低温度下锁定到电荷有序的相称状态。化学计量学CaFe3O5在整个过程中表现出单相行为，避免了相分离成两个不同的晶体相，具有不同的磁性结构和铁价分布，这可能是由于部分Fe2+取代了Ca2+。这强调了这些混合价体系的磁性和化学对组成的敏感性。
Mixed-valent transition metal compounds display complex structural, electronic and magnetic properties which can often be exquisitely tuned. Here the charge-ordered state of stoichiometric CaFe3O5 is probed using neutron powder diffraction, Monte Carlo simulation and symmetry analysis. Magnetic ordering is dominated by the formation of ferromagnetic Fe3+-Fe2+-Fe3+ trimers which are evident above the magnetic ordering transition. Between T-N= 289 K and 281 K an incommensurate magnetically ordered phase develops due to magnetic frustration, but a spin Jahn-Teller distortion lifts the frustration and enables the magnetic ordering to lock in to a charge-ordered commensurate state at lower temperatures. Stoichiometric CaFe3O5 exhibits single phase behaviour throughout and avoids the phase separation into two distinct crystallographic phases with different magnetic structures and Fe valence distributions reported recently, which likely occurs due to partial Fe2+ for Ca2+ substitution. This underlines the sensitivity of the magnetism and chemistry of these mixed-valent systems to composition.