Seminar "Quantum Oscillations at Room Temperature" by Prof. Susumu Fukatsu

• Speaker: Prof. Susumu Fukatsu
• Affiliation: Graduate School of Arts and Sciences, University of Tokyo
• Date: May 25th (Wed)
• Time: 11:00-12:00

Quantum Oscillations at Room Temperature

The Landau levels (LL's) are a series of discrete energy states which develop when a charged particle is placed in a strong magnetic field. The singularity of their density-of-states has allowed the discovery of a rich variety of distinguished physical phenomena such as the quantum Hall effect. They arguably appear at cryogenic temperature, so their observation at room temperature is a challenge. Furthermore, it is intriguing to apply photoluminescence to their characterisation from the experimental point of view. This is because the available spectral window is usually too narrow to cover many split levels in the presence of energy relaxation of the photoexcited carriers. Here, compelling evidence is presented for the well spin-split LL's in the bulk semiconductor Ge at room temperature, which was found in the circular-polarized photoluminescence measurement under pulse excitation. The analysis of the oscillatory direct-gap emission spectra suggests that the survival of the LL's is controlled by intervalley phonon scattering characteristic of the multi-valleyed Ge. Remarkably, a high electron temperature turns even helpful. The well-known criteria for observing the LL's are revisited. 

Hosted by Mathematical and Theoretical Physics (Hikami) Unit