EPR Spectra of TlGaS2 and TlInS2 compounds doped by paramagnetic Fe3+ ions

The results of the EPR investigations of Fe-doped TlGaS2 and TlInS2 single crystals are presented. The crystals were grown in evacuated quartz tubes using the Bridgman method. For EPR experiments, iron was added to the growth mixture in amounts corresponding to a molar ratio Fe/Ga(In) of about 2%(0.7%). The spectra were recorded by using X-band spectrometer. The fine structure of EPR spectra of paramagnetic Fe3+ ions was observed. The spectra were interpreted to correspond to the transitions among spin multiplet of Fe3+ ion, which split in the local ligand crystal field of orthorhombic symmetry. Measured EPR line positions have been analysed to extract Fe3+ spin Hamiltonian parameters using exact diagonalization method. Four twinning Fe3+ centers were observed in Fe doped TlGaS2, while the EPR spectra in TlInS2 did not exhibit twinning. This difference is considered in the frame of peculiarities of the crystal structures of TlGaS2 and TlInS2