Supercondutor-Insulator Transition on Annealed Complex Networks
  Cuprates show multiphase complexity that has hindered physicists search for the mechanism of high T_c for many years. A fingerprint of electronic scale invariance has been reported recently by Fratini et al. by detecting the structural scale invariance of dopants using scanning micro x-ray diffraction. In order to shed light on critical phenomena on these materials, here we propose a stylized model capturing the essential characteristics of the superconducting-isulator transition of a highly dynamical, heterogenous granular material: the Disordered Quantum Tranverse Ising Model (DQTIM) on Annealed Complex Network. We show that when the networks encode for high heterogeneity of the expected degrees described by a power law distribution, the critical temperature for the onset of the supercoducting phase diverges to infinity as the power-law exponent \gamma of the expected degree distribution is less than 3, i.e. \gamma<3. Moreover we investigate the case in which the critical state of the electronic background is triggered by an external parameter g that determines an exponential cutoff in the power law expected degree distribution characterized by an exponent \gamma. We find that for g=g_c the critical temperature for the superconduting-insulator transition has a maximum is \gamma>3 and diverges if \gamma<3. 
Ginestra Bianconi
cond-mat.stat-mech cond-mat.dis-nn