Electron Paramagnetic Resonance of Manganese in Gallium Arsenide

The paramagnetic spin-resonance spectra of manganese in GaAs have been studied at 77°K. Isotropic values for the spectroscopic splitting factor $g$ and for the hyperfine interaction constant $A$ have been measured to be 2.004 and 56 G, respectively. Fine structure lines were not found, even at 4°K. A spin Hamiltonian describing the resonance spectra is given. An estimate of the cubic splitting constant $a$ is deduced from the angular variation of the spectrum.