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】
Free