PhD defense Bence Bernáth: FEL-based THz spectroscopy in high magnetic fields

Friday, September 3, Bence Bernáth successfully defended his thesis on Terahertz spectroscopy of various materials in high magnetic fields. The common point of his different research paths was the utilization of the combination of the high field magnet and the free-electron laser, FLARE, provided by HFML-FELIX.

Bernáth studied how this unique combination can provide a suitable environment for linear and non-linear spectroscopy. His research demonstrates that the FLARE-high field magnet combination can perform high-resolution electron paramagnetic resonance spectroscopy up to 30 T. Due to the tunability of the setup, he explored the low energy electronic excitations in KEr(MoO₄)_{2 ,}  a paramagnetic insulator single crystal, that triggered the research towards a new direction, in which a peculiar magnetostrictive behavior was revealed. This finding provides great perspectives for application in cryogenic and magnetic technologies.

To exploit the combination's full potential that makes use of the intense but short Terahertz radiation in a continuous magnetic field, he developed a single-colour Terahertz pump-probe setup. The first tests were performed on gallium-doped germanium, where the dynamics of hole cyclotron resonance was studied, giving curious insight into the band structure of this well-known semiconductor.

Bernáth's thesis exhibits the versatility of the combination of HFML-FELIX and suggests a way for further development.

Promotor: prof. dr. P.C.M. Christianen
Co-promotor: dr. H. Engelkamp