Electron-like quasiparticles drive the superconductor-insulator transition in homogeneously disordered thin films

Philip Phillips, Denis Dalidovich
2001 Philosophical Magazine B  
Transport data on Bi, MoGe, and PbBi/Ge homogeneously-disordered thin films demonstrate that the critical resistivity, R_c, at the nominal insulator-superconductor transition is linearly proportional to the normal sheet resistance, R_N. In addition, the critical magnetic field scales linearly with the superconducting energy gap and is well-approximated by H_c2. Because R_N is determined at high temperatures and H_c2 is the pair-breaking field, the two immediate consequences are: 1)
more » ... iparticles populate the insulating side of the transition and 2) standard phase-only models are incapable of describing the destruction of the superconducting state. As gapless electronic excitations populate the insulating state, the universality class is no longer the 3D XY model. The lack of a unique critical resistance in homogeneously disordered films can be understood in this context. In light of the recent experiments which observe an intervening metallic state separating the insulator from the superconductor in homogeneously disordered MoGe thin films, we argue that the two transitions that accompany the destruction of superconductivity are 1) superconductor to Bose metal in which phase coherence is lost and 2) Bose metal to localized electron insulator via pair-breaking.
doi:10.1080/13642810110060566 fatcat:ro23z53vb5fyzmhh22clxxcshe