Berlin 2024 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 19: Quantum Coherence (joint session TT/DY)

TT 19.4: Talk

Monday, March 18, 2024, 17:15–17:30, H 3025

Dichroic cavity mode splitting and lifetimes from interactions with ferromagnetic metal — •Henning G. Hugdal, Eirik Jaccheri Høydalsvik, and Sol H. Jacobsen — Center for Quantum Spintronics, Department of Physics, NTNU, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway

We study the effect of ferromagnetic metals (FM) on the circularly polarized modes of an electromagnetic cavity and show that broken time-reversal symmetry leads to a dichroic response of the cavity modes. In the simple model of only one spin split band, the Zeeman coupling between the FM electrons and cavity modes leads to an anticrossing for mode frequencies comparable to the spin splitting. However, this is only the case for one of the circularly polarized modes, while the other is unaffected by the FM. Hence, the cavity photons display a dichroic response to the presence of the FM, allowing for the determination of the spin-splitting of the FM using polarization-dependent transmission experiments. Moreover, using a spin-split two-band model, we show that also the lifetimes of the cavity modes display a polarization dependent response. The reduced lifetime of modes of only one polarization could potentially be used to engineer and control circularly polarized cavities.

Keywords: Cavity; Ferromagnet; Light-matter coupling; Dichroism; Spintronics