Simple method to enhance the coupling of THz electromagnetic pulses to antiferromagnetic spins

Abstract A gold grating deposited on a glass plate and attached to an antiferromagnet is shown to be a simple and universal method to enhance the coupling of THz electromagnetic fields to spin in antiferromagnets. More particularly, a grating designed to efficiently absorb THz radiation at a frequency of 335 GHz enhances the linear coupling between the THz magnetic field and the spins in antiferromagnetic YFeO₃. With the grating, a THz magnetic field is shown to excite spin oscillations at this frequency with a twice greater amplitude than in the case of a bare antiferromagnet.