THE SPIN-PEIERLS TRANSITION BEYOND THE ADIABATIC APPROXIMATION

A. O. DOBRY; D. C. CABRA; G. L. ROSSINI

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Lugar: New York; Año: 2007 vol. 75 p. 45122 - 45131

0163-1829

We develop a theory of the spin-Peierls transition taking into account the three dimensionalcharacter of the phonon field. Our approach does not rely on the adiabatic or mean field treatmentfor the phonons. It is instead based in the exact integration of the phonon field,the exact long wavelength solution of the one chain spin problem, and then a meanfield approximation for the interchain interaction. We show that the spin gap and the criticaltemperature are strongly reduced due to the finite frequency effects of the phonon couplingtransverse to the magnetic chains. We show that the long standing discussion on absence of a softmode in this compound can be naturally resolved within our theory.We claim that our results should be applicable to the inorganicspin-Peierls compound CuGeO$_3$.