Magnetic phase transitions in quantum spin-orbital liquids

Article

关键词: INSULATORS;    CA2RUO4;    STATE;   

DOI  :  10.1103/PhysRevB.101.155112

来源: SCIE

【 摘 要 】

We investigate the spin and orbital correlations of a superexchange model with spin S = 1 and orbital L = 1 relevant for 5d(4) transition-metal Mott insulators [O. N. Meetei et al., Phys. Rev. B 91, 054412 (2015)], using exact diagonalization and density matrix renormalization group (DMRG). For spin-orbit coupling lambda = 0, the orbitals are in an entangled state that is decoupled from the spins. We find two phases with increasing lambda: (I) the S2 phase with two peaks in the structure factor for lambda <= lambda(c1) approximate to 0.34J where J is the ferromagnetic exchange; and, (II) the S1 phase for lambda(c1) < lambda <= lambda(c2) approximate to 1.2J with emergent antiferromagnetic correlations. Both S1 and S2 phases are shown to exhibit power-law correlations, indicative of a gapless spectrum. Upon increasing lambda > lambda(c2) leads to a product state of local spin-orbital singlets that exhibit exponential decay of correlations, indicative of a gapped phase. We obtain insights into the phases from the well-known Uimin-Lai-Sutherland model in an external field that provides an approximate description of our model within mean-field theory.

【 授权许可】

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