%T Magnon-photon coupling in the noncollinear magnetic insulator Cu2OSeO3 %A L Abdurakhimov %A S Khan %A NA Panjwani %A D Breeze %A M Mochizuki %A S Seki %A Y Tokura %A JJL Morton %A H Kurebayashi %V 99 %N 14 %D 2019 %I AMER PHYSICAL SOC %J Physical Review B %L discovery10072598 %X Anticrossing behavior between magnons in the noncollinear chiral magnet Cu2OSeO3 and a two-mode X-band microwave resonator was studied in the temperature range 5–100 K. In the field-induced ferrimagnetic phase, we observed a strong-coupling regime between magnons and two microwave cavity modes with a cooperativity reaching 3600. In the conical phase, cavity modes are dispersively coupled to a fundamental helimagnon mode, and we demonstrate that the magnetic phase diagram of Cu2OSeO3 can be reconstructed from the measurements of the cavity resonance frequency. In the helical phase, a hybridized state of a higher-order helimagnon mode and a cavity mode—a helimagnon polariton—was found. Our results reveal a class of magnetic systems where strong coupling of microwave photons to nontrivial spin textures can be observed. %O This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. / This work received funding from the European Union (EU)’s Horizon 2020 research and innovation programme H2020-ICT-2015 under grant agreement No 688539.