Statistical mechanics of one-dimensional chain with two-level impurities

Daniel F. Calef

Nibedita Bhattacharya, Asesh Roy Chowdhury

An exact solution for the statistical mechanics of a one-dimensional ferromagnetic chain with an impurity under an external magnetic field is obtained by the transfer-matrix method and the results are compared with that of a pure chain without an impurity. Expressions for the free energy and susceptibility are obtained in closed form. The mechanisms of the change of phase variation of the wave vector and correlation length are demonstrated graphically.

L. P. Gor’kov, O. N. Dorokhov, Fedor V. Prigara

O. S. Barišić, Peter Prelovšek, Alexandros Metavitsiadis +1 more

The effect of a single static impurity on the many-body states and on the spin and thermal transport in the one-dimensional anisotropic Heisenberg chain at finite temperatures is studied. Whereas the pure Heisenberg model reveals Poisson level statistics and dissipationless transport due to integrability, we show using the numerical approach that a single impurity induces Wigner-Dyson level statistics and at high enough temperature incoherent transport within the chain, whereby the relaxation time and dc conductivity scale linearly with length.

E. T. Y. Hsieh

E. V. Ezerskaya, V. M. Tsukernik

The effect of impurities on the spectrum of one-magnon excitations of two quasi-one-dimensional spin systems—a double XY chain with an impurity atom and an analogous chain with an impurity link, in which two identical impurity atoms occupy neighboring nodes on different XY chains—is studied. The conditions for the existence of impurity levels and their number are determined for the system with one impurity, and for the system with an impurity link the explicit expressions for the energy and wave functions of localized states are also determined.