Progress of Theoretical Physics Supplement · 2005 · 41 citations · 0 references
Natural SciencesPhysicsCondensed Matter PhysicsMagnetic MaterialsQuantum MechanicsElectronic Band StructureExchange InteractionsMagnetic Properties Of SolidsSpin DynamicsStrongly Correlated Electron SystemsEnergy Gap AnalysisMagnetic ExcitationsMagnetization CurvesMagnon ExcitationsMagnonsRenormalization GroupRenormalization Group TheoryTriplet States
In this paper, we investigate the low-energy properties of the S = 1/2 anriferromagnetic quantum spin tube with the triangular lattice structure. Using the density matrix renormalization group (DMRG) method, we calculate the singlet-triplet excitation gap up to 144 triangles along the leg direction. Analyzing the size dependence of the gap, we find that the system is gapful for α ≪ 1.2. A similar analysis of the low-field edge of the magnetization curve suggests that the system is gapless for α > 1.2.