Insulating ferromagnetism in La4Ba2Cu2O10: an Ab initio wannier function analysis |
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Authors: | Ku Wei Rosner H Pickett W E Scalettar R T |
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Institution: | Department of Physics, University of California, Davis 95616-8677, USA. |
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Abstract: | Microscopic mechanisms of the puzzling insulating ferromagnetism of half-filled La4Ba2Cu2O10 are elucidated with energy-resolved Wannier states. The dominant magnetic coupling, revealed through evaluated parameters (t, U, and J), turns out to be the intersite direct exchange, a currently ignored mechanism that overwhelms the antiferromagnetic superexchange. By contrast, the isostructural Nd4Ba2Cu2O10 develops the observed antiferromagnetic order via its characteristics of a 1D chain. Surprisingly, the in-plane order of both cases is not controlled by coupling between nearest neighbors. An intriguing pressure-induced ferromagnetic to antiferromagnetic transition is predicted. |
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