Spin-Peierls transition of the dimer phase of the $J_1-J_2$ model: Energy cusp and CuGeO$_3$ thermodynamics

Sudip Kumar Saha; Manoranjan Kumar; ZoltÃ¡n G. Soos

paper

Spin-Peierls transition of the dimer phase of the $J_{1} - J_{2}$ model: Energy cusp and CuGeO $_{3}$ thermodynamics

arXiv:1907.03724

Abstract

The spin-Peierls transition is modeled in the dimer phase of the spin- $1/2$ chain with exchanges $J_{1}$ , $J_{2} = I^\pm J_{1}$ between first and second neighbors. The degenerate ground state generates an energy cusp that qualitatively changes the dimerization $I^´ (T)$ compared to Peierls systems with nondegenerate ground states. The parameters $J_{1} = 160$ K, $I^\pm = 0.35$ plus a lattice stiffness account for the magnetic susceptibility of CuGeO $_{3}$ , its specific heat anomaly, and the $T$ dependence of the lowest gap.

4 pages, 5 figures

Spin-Peierls transition of the dimer phase of the J1​−J2​ model: Energy cusp and CuGeO3​ thermodynamics

Abstract

Spin-Peierls transition of the dimer phase of the $J_{1} - J_{2}$ model: Energy cusp and CuGeO $_{3}$ thermodynamics