Charge degrees of freedom in frustrated lattice structures
We study numerically spinless fermions with strong nearest-neighbor repulsion V on frustrated lattice structures that show macroscopically many ground states in the absence of a kinetic energy term (hopping term). A finite hopping amplitude t lifts the macroscopic degeneracy and leads to a small num...
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| Veröffentlicht in: | Physical review / B |
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| Format: | UnknownFormat |
| Sprache: | eng |
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2004
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Tag hinzufügen | Zusammenfassung: | We study numerically spinless fermions with strong nearest-neighbor repulsion V on frustrated lattice structures that show macroscopically many ground states in the absence of a kinetic energy term (hopping term). A finite hopping amplitude t lifts the macroscopic degeneracy and leads to a small number of degenerate ground states. These can be characterized by topological quantum numbers and transformation properties under symmetry operations such as particle-hole interchange. Results for the criss-crossed checkerboard lattice (two-dimensional pyrochlore lattice) with up to 32 fermions support the scenario that translational invariance is restored in the thermodynamic limit, making half-charged quasiparticles possible. A finite entropy of approximately (3?4)ln(4?3) per site is released at low temperatures kBT?tđ?Vø , much below the bare energies t,V . This is familiar from the widely studied models involving spins on frustrated lattices, but in a spinless-fermion model these low-energy excitations are necessarily related to charge degrees of freedom. |
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| Beschreibung: | 11 |
| ISSN: | 2469-9950 |