1106.1830 (S. V. Syzranov et al.)

Strong quantum interference in strongly disordered bosonic insulators    [PDF]

S. V. Syzranov, A. Moor, K. B. Efetov

We study the variable-range hopping (VRH) of bosons in an array of sites with
short-range interactions and a large characteristic coordination number. The
latter leads to strong quantum interference phenomena yet allows for their
analytical study. We develop a functional renormalization group scheme that
repeatedly eliminates high-energy sites properly renormalizing the tunnelling
between the low-energy ones. Using this approach we determine the temperature
and magnetic field dependence of the hopping conductivity and find a large
positive magnetoresistance. With increasing magnetic field the behaviour of the
conductivity crossovers from the Mott's law to an activational behaviour with
the activation gap proportional to the magnetic field.

View original: http://arxiv.org/abs/1106.1830