Magnetic properties of magnetic semiconductor GaAs:Er,O studied by ESR

In order to investigate the magnetic properties of GaAs:Er,O, we performed X-band ESR measurement on three different Er-concentration samples in the temperature region from T = 4.6 K to 18 K. Three types of Er-related ESR signals were observed below 18 K. The temperature dependence of the signal intensities and the result of the line shape analyses suggest that the luminescent related Er centers have a singlet-like ground state: that is, the Er-related centers are not homogenously distributed in GaAs:Er,O, and Er³⁺ ions can be antiferromagnetically coupled via the super exchange interaction. Moreover, we have shown that the Er-concentration dependence of intensities of ESR absorption has a strong correlation with the Er-concentration dependence of the PL intensities of GaAs:Er,O