Interaction effects in non-Hermitian models of vortex physics - art. no. 054508

Vortex lines in superconductors in an external magnetic field slightly tilt ed from randomly distributed parallel columnar defects can be modeled by a system of interacting bosons in a non-Hermitian vector potential and a rand om scalar potential. We develop a theory of the strongly disordered non-Her mitian boson Hubbard model using the Hartree-Bogoliubov approximation and a pply it to calculate the complex energy spectra, the vortex tilt angle, and the tilt modulus of (1 + 1)-dimensional directed flux line systems. We con struct the phase diagram associated with the flux-liquid to Bose-glass tran sition and find that, close to the phase boundary, the tilted flux-liquid p hase is characterized by a band of localized excitations, with two mobility edges in its low-energy spectrum.