Past colloquia and seminars


Competition between spin and orbital dichroism of the terahertz vortex beams at the antiferromagnetic resonance in TbFe3(BO3)4

Academic or specialist Seminar

Terahertz (THz) vortex beams with various combinations of the orbital angular
momenta l=±1, ±2, ±3, and ±4 and the spin angular momentum s = ±1, or
conventional circular polarization, were used for studies of the magnon spectra
at the antiferromagnetic (AFM) resonance conditions in TbFe3(BO3)4 . We
observed strong vortex beam dichroism for the magnon doublet which is split in
the external magnetic field of ±0.5T. The absorption conditions at the magnon
energy depend on the total angular momentum of the light j that is determined
by the combination of the spin and orbital angular momenta: j=s+l. For the
higher orders of l, the selection rules for AFM resonances dictated by l
completely dominate over the ones for conventional circular polarization.

When? 16.12.2019 13:00
Where? PER 08 0.58.5
Chemin du Musée 3
1700 Fribourg
speaker Prof. Andrei Sirenko
Department of Physics, New Jersey Institute of Technology, Newark,
New Jersey 07102, USA
visiting Professor at the Department of Physics, University of Fribourg
Contact DepPH, Groupe Ch. Bernhard
Prof. Andrei Sirenko