Magnetic and optical properties of ytterbium-doped indium phosphide crystals

The intimate relation connecting the magnetic and optical properties of ytterbium-doped indium phosphide is studied under the conditions of local magnetic ordering and compensation of spin correlations by electron-vibration interaction. An analysis of the temperature dependences of the static magnetic susceptibility and photoluminescence spectra shows that the impurity magnetism of InP(Yb) crystals originates from the presence of antiferromagnetically ordered Yb2O3 quasi-molecules, which transfer to a ferromagnetically ordered state in the vicinity of shallow donors by capturing a donor electron or compete to form regions of local magnetic ordering (bound spin polarons). In both cases, the s-f exchange constants, as derived from the temperature dependences of the static magnetic susceptibility, are found to be anomalously large, apparently because of the spin correlations being efficiently compensated by electron-vibration interaction. In addition, due to the s-f exchange, an exchange-coupled deep level of the ferromagnetically ordered Yb2O3 quasi-molecule arises in the band gap of indium phosphide. The formation of this level simulates Auger recombination of nonequilibrium carriers, which is responsible for enhancement of the intracenter photoluminescence of Yb3+ ions.