Transient superconductivity from electronic squeezing of optically pumped phonons
Transient superconductivity from electronic squeezing of optically pumped phonons
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DOI：
10.1038/nphys4024
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发表时间：
2017-05-01
期刊：
影响因子：
19.6
通讯作者：
Millis, Andrew J.
中科院分区：
文献类型：
--
作者：
Kennes, Dante M.;Wilner, Eli Y.;Millis, Andrew J.
光源和时间分辨光谱学的进步使得激发固体中特定的原子振动和观察电子性质的变化成为可能，但是声子激发引起电子性质质变的机制仍然不清楚。本文表明，电子密度和偶极子活动模式之间的主要对称耦合意味着声子态的电子密度依赖压缩，这为电子-电子相互作用提供了有吸引力的贡献，与裸电子-声子耦合的符号无关，并且与激光诱导声子激发的程度成比例。合理的激发振幅导致不可忽略的吸引相互作用，可能导致电子特性的显着瞬态变化，包括超导性。该机制普遍适用于广泛的系统，为操纵和控制新材料中的电子相行为提供了一条有前途的途径。
Advances in light sources and time-resolved spectroscopy have made it possible to excite specific atomic vibrations in solids and to observe the resulting changes in electronic properties, but the mechanism by which phonon excitation causes qualitative changes in electronic properties has remained unclear. Herewe show that the dominant symmetry-allowed coupling between electron density and dipole active modes implies an electron-density-dependent squeezing of the phonon state that provides an attractive contribution to the electron-electron interaction, independent of the sign of the bare electron-phonon coupling and with a magnitude proportional to the degree of laser-induced phonon excitation. Reasonable excitation amplitudes lead to non-negligible attractive interactions that may cause significant transient changes in electronic properties, including superconductivity. The mechanism is generically applicable to a wide range of systems, offering a promising route to manipulating and controlling electronic phase behaviour in novel materials.