Structural Lifshitz Point in the Quasi D=1 Magnetostrictive XY Model

摘要

The peculiar phase diagram of the d = 1 first-neighbour spin - 1/2 magnetostrictive XY model (with crystalline degrees of freedom assumed three-dimensional) is obtained in the presence of a magnetic field along the Z-axis. The structural instability wave vector continuosly varies along the second order critical line. This variation presents two non trivial points: one of them corresponds, in the phase diagram, to a Lifshitz point, where the uniform and dimerized phases converge with a (complex) modulated one; the other one presents characteristics which, to the best of our knowledge, have never been observed. (Atomindex citation 13:700928)