We add magnetic ions into quantum wells in microcavities in order to fabricate semimagnetic microcavities. In such a structure, polaritons are very sensitive to spin dependent phenomena, e.g. they exhibit angle dependent Giant Zeeman effect,

"Angular dependence of giant Zeeman effect for semi-magnetic cavity polaritons", R. Mirek, M. Król, K. Lekenta, J.-G. Rousset, M. Nawrocki, J. Szczytko, M. Kulczykowski, M. Matuszewski, W. Pacuski, B. Piętka, Phys. Rev. B 95, 085429 (2017). .

threshold of polariton condensation is strongly reduced under magnetic field,

"Effect of magnetic field on the lasing threshold of a semimagnetic polariton condensate", J.-G. Rousset, B. Piętka, M. Król, R. Mirek, K. Lekenta, J. Szczytko, W. Pacuski, M. Nawrocki, Phys. Rev. B 96, 125403 (2017) .

polariton condensate is either spin-polarized,

"Spin polarized semimagnetic exciton-polariton condensate in magnetic field", M. Król, R. Mirek, K. Lekenta, J.-G. Rousset, D. Stephan, M. Nawrocki, M. Matuszewski, J. Szczytko, W. Pacuski, B. Piętka, Scientific Reports 8, 6694 (2018).

or exhibits spin Meissner effect, so vanishing of spin polarization,

"Giant spin Meissner effect in a non-equilibrium exciton-polariton gas", M. Król, R. Mirek, D. Stephan, K. Lekenta, J.-G. Rousset, W. Pacuski, A. V. Kavokin, M. Matuszewski, J. Szczytko, B. Piętka, Phys Rev. B 99, 115318 (2019).

We observed also that magnetic field affects symmetry of interacting polariton condensates,

"Magneto-optical induced supermode switching in quantum fluids of light", M. Furman, R. Mirek, M. Król, W. Pacuski, H. Sigurðsson, J. Szczytko, B. Piętka, Communications Physics 6, 196 (2023).

and magnetic tuning is useful for coupling distant QWs by photonic modes of double or single microcavites

"Long-distance coupling and energy transfer between exciton states in magnetically controlled microcavities", M. Ściesiek, K. Sawicki, W. Pacuski, K. Sobczak, T. Kazimierczuk, A. Golnik, J. Suffczyński , Communications Materials 1, 78 (2020).

"Hybrid Semimagnetic Polaritons in a Strongly Coupled Optical Microcavity", T. Fąs, M. Ściesiek, W. Pacuski, A. Golnik, J. Suffczyński, J. Phys. Chem. Lett. 12, 7619 (2021).     , Press release: PL.