Moor Andreas, Volkov Anatoly F, Efetov Konstantin B
Theoretische Physik III, Ruhr-Universität Bochum, D-44780 Bochum, Germany.
Phys Rev Lett. 2017 Jan 27;118(4):047001. doi: 10.1103/PhysRevLett.118.047001.
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 δ|Δ|{Ω}exp(iΩt) of the superconducting gap is excited by an external ac electric field E{Ω}exp(iΩt) already in the first order in |E_{Ω}|, so that δ|Δ|{Ω}∝(v{0}E_{Ω}), where v_{0} is the velocity of the condensate. The frequency dependence δ|Δ|{Ω} has a resonance shape with a maximum at Ω=2Δ. In contrast to the standard situation without the condensate flow, the oscillations of the amplitude δ|Δ(t)| contribute to the admittance Y{Ω}. We provide a formula for admittance of a superconductor with a supercurrent. The predicted effect opens new ways of experimental investigation of the amplitude mode in superconductors and materials with superconductivity competing with other states.
我们考虑具有凝聚流（超电流）的超导体中的振幅（希格斯）模式。我们证明，在这种情况下，对应于超导能隙振荡δ|Δ|{Ω}exp(iΩt)的振幅模式在外部交流电场E{Ω}exp(iΩt)作用下，在|E_{Ω}|的一阶项中就被激发，使得δ|Δ|{Ω}∝(v{0}E_{Ω})，其中v_{0}是凝聚的速度。频率依赖关系δ|Δ|{Ω}具有共振形状，在Ω = 2Δ处达到最大值。与没有凝聚流的标准情况不同，振幅δ|Δ(t)|的振荡对导纳Y{Ω}有贡献。我们给出了具有超电流的超导体的导纳公式。所预测的效应为超导体内以及超导与其他状态竞争的材料中振幅模式的实验研究开辟了新途径。
