Fizika Nizkikh Temperatur: Volume 44, Number 12 (December 2018), p. 1645-1653 ( to contents , go back )
Low-temperature properties of finite XX-chains with an additional Ising spin
A.V. Artemov and E.V. Ezerskaya
V.N. Karazin Kharkiv National University, Kharkiv 61022, Ukraine
Received Jule 9, 2018, published online October 26, 2018
This work is devoted to the theoretical study of quantum stationary states and thermodynamics of two exactly solvable quantum models: a finite linear XX-chain with an additional ZZ-bond (Ising) on one of the intermediate nodes and two distinct finite XX-chains, connected through an additional ZZ-spin on one of the intermediate nodes each of the chains. It is shown that localized levels near the impurity spin may exist in the spectrum, and conditions for their appearance are found. The field and temperature dependences of the main thermodynamic characteristics of models are studied.
Key words: spin, Heisenberg Hamiltonian, Ising model, XX-chain, energy spectrum, thermodynamic characteristics, quantum phase transition.