题 目：Superconductor to insulator transition in Co-cluster/Bi bilayers
报告人：邢玉涛 博士
单 位：巴西Universidade Federal Fluminense大学
时 间：1月12日(周四) 10：00
地 点：李薰楼468室
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Superconductor to insulator transition in Co-cluster/Bi bilayers
Yutao Xing1, W.T. Herrera2, I. C. Souza Dinóla2, H. Micklitz2, E. Baggio-Saitovitch2
1Instituto de Física, Universidade Federal Fluminense, Niterói,Brazil
2Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro, Brazil
Superconductor/ferromagnet (SC/FM) Co-cluster/Bi bilayers have been prepared in this work. The Co-clusters were deposited on the substrate at 40 K and later on coated with Bi film at 4.2 K. In-situ resistivity measurements of Co/Bi samples indicate the as-prepared sample has a full superconducting transition as we expected due to formation of amorphous Bi. After annealing at different temperatures, the Bi layer has a transition from amorphous to crystalline state, which results the superconducting transition partially or fully suppressed in the sample. By changing the annealing temperature, the sample undergoes a transition from superconductor to insulator. The behavior of the resistance as a function of temperature after annealing changed from tunneling among bad contacts(R = R0·exp[(T0/T)1/2]) to a power law (R = R0·T-2/3). It could be an indication of the existence of a quantum critical point in our sample at zero temperature between the superconducting and insulating state.
e-mail: xing@if.uff.br
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