Observation of Excitation of the Antiferromagnetic Mode in the Paramagnetic State of (C2H5NH3)2CuCl4

Abstract
A magnetic resonance line has been observed in the paramagnetic state of the layer compound (C2H5NH3)2CuCl4, which corresponds to the direct antiferromagnetic-mode excitation and which allows the determination of the angular and temperature dependence of the interlayer exchange field HE. This line can be seen up to almost 2TN.