科研之友
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摘要
We consider the amplitude (Higgs) mode in a superconductor with a condensate flow (supercurrent). We demonstrate that, in this case, the amplitude mode corresponding to oscillations delta vertical bar Delta vertical bar(Omega) expd(i Omega t) of the superconducting gap is excited by an external ac electric field E-Omega expd(i Omega t) already in the first order in vertical bar E-Omega vertical bar, so that delta vertical bar Delta vertical bar(Omega) proportional to (v(0)E (Omega)) where v(0) is the velocity of the condensate. The frequency dependence delta vertical bar Delta vertical bar(Omega) has a resonance shape with a maximum at Omega = 2 Delta In contrast to the standard situation without the condensate flow, the oscillations of the amplitude delta vertical bar Delta(t) vertical bar contribute to the admittance Y-Omega. We provide a formula for admittance of a superconductor with a supercurrent. The predicted effect opens new ays of experimental investigation of the amplitude mode in superconductors and materials with superconductivity competing with other states.
- 出版日期2017-1-27
