| Zugriffsnummer | 37402 |
| Dokumenttyp | Konferenzartikel |
| Sprache | Englisch |
| Titel | Terahertz spectroscopy of the berry curvature |
| Autor(in); Institution |
Priyadarshi, Shekhar; 2.5, Halbleiterphysik und Magnetismus, PTB-Braunschweig
Pierz, Klaus; 2.5, Halbleiterphysik und Magnetismus, PTB-Braunschweig
Bieler, Mark; 2.5, Halbleiterphysik und Magnetismus, PTB-Braunschweig
|
| Quelle/Jahr | Proceedings of the International Conference Nonlinear Optics and Excitation Kinetics in Semiconductors (NOEKS) 13:(2016), 37 |
| Availability | [Online only] |
| URL | |
| Konferenzangaben | International Conference Nonlinear Optics and Excitation Kinetics in Semiconductors (NOEKS) 13, Dortmund, 09-13, October, 2016, Germany |
| Zusammenfassung | The Berry curvature Ω is an intrinsic property of crystals and is as fundamental as the effective mass. It resembles a magnetic monopole in momentum space and has important implications on many electronic properties leading to fascinating physical effects, e.g., quantum Hall, spin Hall, and anomalous Hall effects. In a semiconductor exposed to an electric field, Ω also leads to a macroscopic anomalous velocity 〈v〉a in the absence of a magnetic field. In this case, carriers with a particular spin move in a direction perpendicular to the electrical bias. This effect provides an attractive tool for the detection and detailed investigation of Ω. However, 〈v〉a may also result from carrier scattering and, so far, no straightforward distinction between Ω (intrinsic) and scattering (extrinsic) contributions has been achieved. Here, we induce 〈v〉a in an undoped (110)-oriented GaAs quantum well (QW) sample with a well width of 28 nm on a femtosecond time scale and study its temporal evolution with sub-picosecond time resolution to distinguish among the various microscopic origins of 〈v〉a. For this purpose we provide the electrical bias in the plane of the QW using free-space single-cycle THz pulses. Carriers with a certain spin orientation are excited by circularly-polarized optical femtosecond pulses in the QW. This combined optical and THz excitation induces 〈v〉a perpendicular to the polarization of the incident THz radiation. As a result THz radiation whose polarization is perpendicular to the polarization of the incident THz radiation is emitted. We perform a time-resolved study of this THz emission versus delay between the optical and THz excitation pulses (τ). Our measurements not only facilitate a clear identification of intrinsic and extrinsic effects but also provide access to ultrafast and coherent phenomena influencing 〈v〉a. |
