Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2000-02-17
Physics
Condensed Matter
Strongly Correlated Electrons
16 pages, 5 figures
Scientific paper
10.1103/PhysRevB.62.2346
A tight binding model is introduced to describe the strong interaction limit of excitonic ordering. At stoichiometry, the model reduces in the strong coupling limit to a pseudo-spin model with approximate U(4) symmetry. Excitonic order appears in the pseudo-spin model as in-plane pseudo-magnetism. The U(4) symmetry unifies all possible singlet and triplet order parameters describing such states. Super-exchange, Hunds-rule coupling, and other perturbations act as anisotropies splitting the U(4) manifold, ultimately stabilizing a paramagnetic triplet state. The tendency to ferromagnetism with doping (observed experimentally in the hexaborides) is explained as a spin-flop transition to a different orientation of the U(4) order parameter. The physical mechanism favoring such a reorientation is the enhanced coherence (and hence lower kinetic energy) of the doped electrons in a ferromagnetic background relative to the paramagnet. A discussion of the physical meaning of various excitonic states and their experimental consequences is also provided.
No associations
LandOfFree
Excitonic order at strong-coupling: pseudo-spins, doping, and ferromagnetism does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Excitonic order at strong-coupling: pseudo-spins, doping, and ferromagnetism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Excitonic order at strong-coupling: pseudo-spins, doping, and ferromagnetism will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-312536