Quantized Berry Phases for a Local Characterization of Spin Liquids in Frustrated Spin SystemsReport as inadecuate



 Quantized Berry Phases for a Local Characterization of Spin Liquids in Frustrated Spin Systems


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Recently by using quantized Berry phases, a prescription for a local characterization of gapped topological insulators is given. One requires the ground state is gapped and is invariant under some anti-unitary operation. A spin liquid which is realized as a unique ground state of the Heisenberg spin system with frustrations is a typical target system, since pairwise exchange couplings are always time-reversal invariants even with frustrations. As for a generic Heisenberg model with a finite excitation gap, we locally modify the Hamiltonian by a continuous SU2 twist only at a specific link and define the Berry connection by the derivative. Then the Berry phase evaluated by the entire many-spin wavefunction is used to define the local topological order parameter at the link. We numerically apply this scheme for several spin liquids and show its physical validity.



Author: Yasuhiro Hatsugai

Source: https://archive.org/







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