Critical properties of gapped spin-1/2 chains and ladders in a magnetic field

Article

关键词: GROUND-STATE;    HEISENBERG-ANTIFERROMAGNET;    PEIERLS TRANSITION;    COMPOUND CUGEO3;    2 DIMENSIONS;    PHASE;    SYSTEMS;    EXPONENTS;    RESONANCE;    MODELS;   

DOI  :  10.1103/PhysRevB.55.5816

来源: SCIE

【 摘 要 】

An interesting feature of spin-1/2 chains with a gap is that they undergo a commensurate-incommensurate transition in the presence of an external magnetic field H. The system is in a gapless incommensurate regime for all values of the magnetic field between the lower critical field H-c1 and an upper critical field H-c2, when it is gapless and has power-law correlations. We calculate the critical exponents for such a generic gapped system in the incommensurate regime at the critical field H-c1 and in its vicinity. Our analysis also applies to the spin-1/2 ladder. We compute the full dynamical susceptibilities at finite temperature. We use the same to discuss the thermal broadening of various modes and obtain the low-temperature behavior of the nuclear spin relaxation rate T-1(-1). We discuss the results obtained here for the special cases of the dimerized chain, frustrated chain, and the spin-1/2 ladder.

【 授权许可】

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