|VOLUME 106 | ISSUE 7 |
Unconventional spin-charge phase separation in a model 2D cuprate
Yu. D. Panov, K. S. Budrin, A. A. Chikov, A. S. Moskvin
Ural Federal University, 620083 Ekaterinburg, Russia
In this Letter we address a challenging problem of a competition of charge
and spin orders for high-Tc cuprates within a simplified 2D
spin-pseudospin model which takes into account both conventional Heisenberg
Cu2+-Cu2+ antiferromagnetic spin exchange coupling (J) and the
on-site (U) and inter-site (V) charge correlations in the CuO2 planes
with the on-site Hilbert space reduced to only three effective charge states
(nominally Cu1+;2+;3+). We performed classical Monte-Carlo calculations
for large square lattices implying the mobile doped charges and focusing on a
case of a small inter-site repulsion . The on-site attraction (U<0)
does suppress the antiferromagnetic ordering and gives rise to a checkerboard
charge order with the doped charge distributed randomly over a system in the
whole temperature range. However, under the on-site repulsion (U>0)
the homogeneous ground state antiferromagnetic solutions of the doped system
found in a mean-field approximation are shown to be unstable with respect to
a phase separation with the charge and spin subsystems behaving like
immiscible quantum liquids. Puzzlingly, with lowering the temperature one
can observe two sequential phase transitions: first, an antiferromagnetic
ordering in the spin subsystem diluted by randomly distributed charges,
then, a charge condensation in the charge droplets.
The effects are illustrated by the Monte-Carlo calculations of the specific
heat and longitudinal magnetic susceptibility.
Список работ, цитирующих данную статью, см. здесь.
List of articles citing this article can be found here.