in high magnetic fields*

LiCoPO4 belongs to the family of magnetoelectric lithium-orthophosphates. In these compounds the cross-coupling between magnetization and electric polarization leads to variety of spin excitations that have entangled dynamic electric and magnetic properties. In this work THz spectroscopy was used to measure absorption spectra of spin excitations in LiCoPO₄ single crystal below antiferromagnetic ordering temperature and in magnetic field up to 32 T. Three spin flop transitions for the magnetic field parallel to the magnetic easy axis were identified from the magnetic field dependence of spin excitations and from the magnetic field dependence of magnetization. Using polarized light and ME poling to create a single ME domain [V. Kocsis et al. PRL121, 057601 (2018), PRB100, 155124 (2019)], the selection rules of spin excitations were determined. Several magnetic-, electric-dipole active and magnetoelectric resonances were found.