European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex, France.
London Centre for Nanotechnology and Department of Physics and Astronomy, University College London, London WC1E 6BT, United Kingdom and Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, United Kingdom.
Phys Rev Lett. 2014 Jan 17;112(2):026403. doi: 10.1103/PhysRevLett.112.026403. Epub 2014 Jan 15.
The resonant x-ray scattering (magnetic elastic, RXMS, and inelastic, RIXS) of Ir4+ at the L2,3 edges relevant to spin-orbit Mott insulators A(n+1)Ir(n)O(3n+1) (A = Sr, Ba, etc.) are calculated using a single-ion model which treats the spin-orbit and tetragonal crystal-field terms on an equal footing. Both RXMS and RIXS in the spin-flip channel are found to display a nontrivial dependence on the direction of the magnetic moment, μ. Crucially, we show that for μ in the ab plane, RXMS in the cross-polarized channel at the L2 edge is zero irrespective of the tetragonal crystal field; spin-flip RIXS, relevant to measurements of magnons, behaves reciprocally, being zero at L2 when μ is perpendicular to the ab plane. Our results have important implications for the assignment of a j(eff) = 1/2 ground state on the basis of resonant x-ray experiments.
利用单离子模型计算了 Ir4+ 在 L2,3 边缘的共振 X 射线散射（磁弹性、RXMS 和非弹性、RIXS），该模型平等对待自旋轨道和四方晶场项。在自旋翻转通道中，RXMS 和 RIXS 都发现与磁矩 μ 的方向存在非平凡的依赖关系。至关重要的是，我们表明，对于 μ 在 ab 平面内，L2 边缘的交叉极化通道中的 RXMS 无论四方晶场如何都为零；与测量磁子相关的自旋翻转 RIXS 表现出反向行为，当 μ 垂直于 ab 平面时，L2 处为零。我们的结果对基于共振 X 射线实验分配 j(eff) = 1/2 基态具有重要意义。
