Synthesis and transport properties of superconducting thin films ofK0.33WO3:Tcreduction due to disorder

Synthesis and ionic liquid gating of hexagonal WO3 thin films

“…1 For example, due largely to the electrochromic effect found in WO 3 , the material is an integral part of smart windows technology, dye-sensitized solar cells, and hydrogen sensing. 2,3 By doping with alkali metals, WO 3 may be promising for battery technology 4,5 and is superconducting, [6][7][8] with tantalizing reports of very high superconducting transition temperature anomalies. 9,10 Despite the numerous technological advances attained with this material, a deeper understanding of the underlying optical and electronic mechanisms is still under intense debate.…”

Point-contact tunneling spectroscopy measurement ofCuxTiSe2: Disorder-enhanced Coulomb effects

“…Previous studies using these tips demonstrate that they provide a tunneling contact, and the normalized differential conductance, G/G(25mV ), shown in Fig. 2 allows for a direct measure of the normalized DOS N (E) 9,11 . For the superconducting sample, we are essentially probing the behavior in the normal state in this temperature range.…”

“…These cusps are reminiscent of those observed in amorphous Nb-Si alloys, 12 which is one of the classic cases of a disorder driven metal-insulator transition, and more recently such cusps were observed in BPBO and alkalidoped tungsten bronzes. 9,11 In disordered metals, the reduction of N (E) due to disorder-enhanced Coulomb interactions is well established. In three dimensions theory predicts that…”

“…Disorder can play different roles depending on the material system and has been shown to be important in several distinct superconducting systems recently 9,11 . For comparison, in Fig.…”

“…In Cu x TiSe 2 , the disorder seems to play a different role, that is it suppresses the CDW and allows T c to occur. In order to provide a theoretical framework to address this question, we apply the same formalism as was used previously in 9,11 . Briefly, from the work of Belitz, 14 we have a modified McMillan equation for T c valid for strong coupling and relatively strong disorder.…”