Theoretical Study on the Spin-State Transition of Electron-Doped Sr2−x La x CoO4 Compounds
The spin-state transition is an interesting and unresolved problem in layered perovskite Sr2−x La x CoO4 under doping. The unrestricted Hartree-Fock approximation on a realistic multiband lattice model has been applied to study the various spin states of electron-doped Sr2−x La x CoO4 compounds. In the doping range 0.0≤x≤0.9, various spin states in an enlarged double cell are investigated and four of them are the ground states at different doping concentration. The magnetic ground state of the doped system takes a low-spin–intermediate-spin ferromagnetically ordered state for x<0.26, a high-spin–intermediate-spin ferromagnetically ordered state for 0.26≤x<0.47, an intermediate-spin state for 0.47≤x<0.65, and followed by an high-spin antiferromagnetically ordered state for 0.65≤x≤0.9. The densities of states of all magnetic ground states are computed and their electronic and magnetic properties are discussed.
KeywordsRecursion method Hartree–Fock approximation Density of state Doping concentration Layered perovskite Magnetic ground state
This work is supported by Teachers’ Scientific Research Fund of China Earthquake Administration (20120121). We are very grateful to Professor Aimin Sun for kindly offering his advice.
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