|標題：Low energy orbital excitations in strained LaCoO3 films|
|作品名稱||Low energy orbital excitations in strained LaCoO3 films|
|著者||Ru-Pan Wang; Jaap Geessinck; Hebatalla Elnaggar; Keisuke Tomiyasu; Jun Okamoto; Boyang Liu; Chao-Hung Du; Di-Jing Huang; Gertjan Koster,; Frank M. F. de Groot|
|著錄名稱、卷期、頁數||Phys. Rev. B 100(16), 165148|
|摘要||We present 90 meV resolved Co 2p3d resonant inelastic x-ray scattering linear dichroism spectra of strained LaCoO3 films and a LaCoO3 single crystal. A polarization-dependent low-energy excitation is observed at ∼0.2eV on the tensile-strained LaCoO3/SrTiO3 film, while it is not observed in either bulk LaCoO3 or the compressive-strained LaCoO3/LaAlO
3 film. Guided by cluster calculations, we are able to distinguish the spin-state manifolds close to their transition point of Co3+ ions in
LaCoO3 systems. Through a polarization analysis, we show that the spin state can easily flip from a low-spin 1A1g state in an octahedral symmetry to the high-spin 5B2g or 5Eg states with a small tetragonal distortion. A mixture of spin states suggests that the high-spin
Co3+ plays an important role in long-range ferromagnetic order on both tensile- and compressive-strained LaCoO3 films.