Ritter M F, Crescini N, Haxell D Z, Hinderling M, Riel H, Bruder C, Fuhrer A, Nichele F
IBM Quantum, IBM Research-Zurich, Rüschlikon, Switzerland.
Department of Physics, University of Basel, Basel, Switzerland.
Nat Electron. 2022;5(2):71-77. doi: 10.1038/s41928-022-00721-1. Epub 2022 Feb 28.
Recent experiments have suggested that superconductivity in metallic nanowires can be suppressed by the application of modest gate voltages. The source of this gate action has been debated and either attributed to an electric-field effect or to small leakage currents. Here we show that the suppression of superconductivity in titanium nitride nanowires on silicon substrates does not depend on the presence or absence of an electric field at the nanowire, but requires a current of high-energy electrons. The suppression is most efficient when electrons are injected into the nanowire, but similar results are obtained when electrons are passed between two remote electrodes. This is explained by the decay of high-energy electrons into phonons, which propagate through the substrate and affect superconductivity in the nanowire by generating quasiparticles. By studying the switching probability distribution of the nanowire, we also show that high-energy electron emission leads to a much broader phonon energy distribution compared with the case where superconductivity is suppressed by Joule heating near the nanowire.
近期实验表明，适度施加栅极电压可抑制金属纳米线中的超导性。这种栅极作用的来源一直存在争议，要么归因于电场效应，要么归因于小泄漏电流。在此我们表明，硅基衬底上氮化钛纳米线中超导性的抑制并不取决于纳米线处是否存在电场，而是需要高能电子流。当电子注入纳米线时，抑制效果最为显著，但当电子在两个远距离电极之间通过时也能得到类似结果。这可以通过高能电子衰变为声子来解释，声子通过衬底传播，并通过产生准粒子来影响纳米线中的超导性。通过研究纳米线的开关概率分布，我们还表明，与纳米线附近焦耳热抑制超导性的情况相比，高能电子发射会导致更宽的声子能量分布。
