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Mardi 19 mars 2019 - 14:00

Approaching frustrated magnetism with symmetric PEPS

Ji-Yao Chen (LPT Toulouse)

par Revaz Ramazashvili - 19 mars 2019

In two dimensions, Projected Entangled-Pair States (PEPS) are elegant many-body wavefunctions which capture efficiently the quantum entanglement of ground states of local quantum spin Hamiltonians. Combining the framework of PEPS with various symmetries, e.g. SU(2) spin rotation symmetry, translation symmetry, and point group symmetry, which are present in typical Heisenberg antiferromagnets, a comprehensive classification of PEPS tensors on the square lattice has been achieved. Using tensors belonging to some specific classes as a variational manifold allows us to study frustrated magnets in a controlled way. To illustrate the complexity of these manifolds, I will first present the phase diagram of a one-parameter family of long-range resonating valence bond (RVB) state, where we found a topological Z_2 RVB phase, sandwiched by two critical phases. Then I will move on to using these manifolds to study frustrated spin-1 antiferromagnets, where a nematic spin liquid phase and a non-abelian chiral spin liquid phase have been identified. Some perspectives will also be discussed at the end.

Post-scriptum :

Contact : D. Poilblanc, R. Ramazashvili