Yin Zhong, Ke Liu, Yong-Qiang Wang, Hong-Gang Luo
A novel gapped metallic state coined orthogonal Dirac semimetal is identi?ed in the honeycomb lattice in terms of Z2 slave-spin representation of Hubbard model. This state corresponds to the disordered phase of slave-spin and has the same thermal-dynamical and transport properties as Dirac semimetal but its singe-particle excitation is gapped. The quantum phase transition from this orthogonal Dirac semimetal to usual Dirac semimetal is described by nearly exact mean-?eld decou- pling and its criticality falls into the universality class of 2+1D Ising model while a large anomalous dimension for the physical electron is found at quantum critical point (QCP), which could be con- sidered as a ?ngerprint of our fractionalized theory when compared to other non-fractionalized approaches. As byproducts, a path integral formulism for the Z2 slave-spin representation of Hub- bard model is constructed and possible relations to other approaches and the sublattice pairing states, which has been argued to be a promising candidate for gapped spin liquid state found in the numerical simulation, are brie y discussed. We hope the present work may be helpful for future studied in Z2 slave-spin theory and related non-Fermi liquid phases in honeycomb lattice.
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http://arxiv.org/abs/1205.6064
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