Spin diffusion in the one-dimensional s = 1/2 XXZ model at infinite temperature

Authors

Markus Böhm
V. S. Viswanath, University of Rhode Island
Joachim Stolze, University of Rhode Island
Gerhard Müller, University of Rhode IslandFollow

Document Type

Article

Date of Original Version

6-1-1994

Embargo Date

6-1-1994

Abstract

Time-dependent spin-autocorrelation functions at T = ∞ and (in particular) their spectral densities for the bulk spin and the boundary spin of the semi-infinite spin-1/2 XXZ model (with exchange parameters J_x = J_y = J, J_z) are investigated on the basis of (i) rigorous bounds in the time domain and (ii) a continued-fraction analysis in the frequency domain. We have found strong numerical evidence for spin diffusion in quantum spin models. For J_z/J increasing from zero, the results of the short-time expansion indicate a change of the bulk-spin xx-autocorrelation function from Gaussian decay to exponential decay. The continued-fraction analysis of the same dynamic quantity signals a change from exponential decay to power-law decay as J_z/J pproaches unity and back to a more rapid decay upon further increase of that parameter. By contrast, the change in symmetry at J_z/J = 1 has virtually no impact on the bulk-spin zz-autocorrelation function (as expected). Similar contrasting properties are observable in the boundary-spin autocorrelation functions.

Citation/Publisher Attribution

Markus Böhm, V.S. Viswanath, Joachim Stolze and Gerhard Müller. Spin diffusion in the 1D s=1/2 XXZ model at infinite temperature. Phys. Rev. B 49 (1994), 15669-15681.

Available at http://journals.aps.org/prb/abstract/10.1103/PhysRevB.49.15669.

Publisher Statement

Copyright 1994 The American Physical Society.