G. Albertini | Searcharxiv

arXiv1998

A novel exponent in the Equilibrium Shape of Crystals

A new exponent characterizing the rounding of crystal facets is found by mapping a crystal surface onto the asymmetric six-vertex model (i.e. with external fields h and v) and using the Bethe Ansatz to obtain appropriate expansions of the free energy close to criticality. Leading order exponents in δh, δv are determined along the whole phase boundary and in an arbitrary direction. A possible experimental verification of this result is discussed.

cond-mat.stat-mech↗

arXiv1995

$XXZ$ model as effective Hamiltonian for generalized Hubbard models with broken $η$-symmetry

We consider the limit of strong Coulomb attraction for generalized Hubbard models with $η$-symmetry. In this limit these models are equivalent to the ferromagnetic spin-1/2 Heisenberg quantum spin chain. In order to study the behaviour of the superconducting phase in the electronic model under perturbations which break the $η$-symmetry we investigate the ground state of the ferromagnetic non-critical $XXZ$-chain in the sector with fixed magnetization. It turns out to be a large bound state of $N$ magnons. We find that the perturbations considered here lead to the disappearance of the off-diagonal longe-range order.

cond-mat↗