59 research outputs found
Analysis of Charge-spin-orbital Fluctuations by Ab Initio Calculation and Random Phase Approximation: Application to Non-coplanar Antiferromagnet Cd2Os2O7
We present a systematic analysis on the basis of ab initio calculations and
many-body perturbation theory for clarifying the dominant fluctuation in
complex charge-spin-orbital coupled systems. For a tight-binding multiband
model obtained from the maximally-localized Wannier function analysis of the
band structure by the local density approximation, we take into account
electron correlations at the level of random phase approximation. To identify
the dominant fluctuation, we carry out the eigenmode analysis of the
generalized susceptibility that includes all the multiple degrees of freedom:
charge, spin, and orbital. We apply this method to the paramagnetic metallic
phase of a pyrochlore oxide CdOsO, which shows a metal-insulator
transition accompanied by a peculiar noncoplanar antiferromagnetic order of
all-in all-out type. We find that the corresponding spin fluctuation is
dominantly enhanced by the on-site Coulomb repulsions in the presence of strong
spin-orbit coupling and trigonal crystal field splitting. Our results indicate
that the combined method offers an effective tool for the systematic analysis
of potential instabilities in strongly correlated electron materials.Comment: 8 pages, 4 figure
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