Abstract
We study an orbital compass model on a checkerboard lattice where orbital degree of freedom is represented by the pseudospin operator. Competition arises from an Ising interaction for the z component of pseudospins along the vertical/horizontal bonds and an Ising interaction for the x component along diagonal bonds. Classical and quantum compass models are analyzed by utilizing several analytical methods and numerical simulations. At a fully frustrated point where the two Ising interactions compete with each other, a macroscopic number of orbital configurations are degenerate in a classical ground state. This degeneracy is lifted by thermal and quantum fluctuations, and a staggered long-range order of the z component of the pseudospin is realized. A tricritical point for this order appears due to competition between the bond dependent Ising interactions. Roles of geometrical frustration on excitation dynamics are also examined.
Original language | English |
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Article number | 205141 |
Journal | Physical Review B - Condensed Matter and Materials Physics |
Volume | 85 |
Issue number | 20 |
DOIs | |
Publication status | Published - 2012 May 29 |
Externally published | Yes |
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics