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arXiv · 1104.1432

Z2 spin liquid in S=1/2 Heisenberg model on Kagome lattice: A projective symmetry group study of Schwinger-fermion mean-field states

Yuan-Ming Lu·Ying Ran·Patrick A. Lee
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Abstract

With strong geometric frustration and quantum fluctuations, S=1/2 quantum Heisenberg antiferromagnets on the Kagome lattice has long been considered as an ideal platform to realize spin liquid (SL), a novel phase with no symmetry breaking and fractionalized excitations. A recent numerical study of Heisenberg S=1/2 Kagome lattice model (HKLM) show that in contrast to earlier studies, the ground state is a singlet-gapped SL with signatures of Z2 topological order. Motivated by this numerical discovery, we use projective symmetry group to classify all 20 possible Schwinger-fermion mean-field states of Z2 SLs on Kagome lattice. Among them we found only one gapped Z2 SL (which we call Z2[0,π]βstate) in the neighborhood of U(1)-Dirac SL state, whose energy is found to be the lowest among many other candidate SLs including the uniform resonating-valentce-bond states. We thus propose this Z2[0,π]βstate to be the numerically discovered SL ground state of HKLM.

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Yuan-Ming Lu, Ying Ran, Patrick A. Lee. 2011-06-23. Z2 spin liquid in S=1/2 Heisenberg model on Kagome lattice: A projective symmetry group study of Schwinger-fermion mean-field states. https://doi.org/10.1103/physrevb.83.224413

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