Electron spin resonance studies on the superlattices PbTe-Pb 1 - x>Eu xTe prepared by hot wall epitaxy

Abstract

Electron spin resonance spectra of the superlattices PbTe-Pb 1 - xEu xTe prepared by a hot wall epitaxy technique have been examined, in which x denotes the fraction of europium or periodic monolayers of Pb 1 - xEu xTe calculated by assuming no diffusion of europium(II) into the PbTe layer. For the spectra of the superlattices the linewidth was found to vary markedly over the range of x between 0.1 and 1, proving that most of the europium(II) exists on the monolayer of Pb 1 - xEu xTe. An inhomogeneous distribution of europium(II) of the monolayer of Pb 1 - xEu xTe and diffusion of a small amount of europium into the PbTe layer were presumed on the basis of the data on the linewidth and on the intensity variation of the resonance due to both dipole-dipole and exchange interactions. In the case of randomly europium-doped crystalline Pb 1 - yEu yTe of y = 0.003, in which y is the fraction of europium doped in the crystalline PbTe, the overall splitting of the ground state parameter of europium(II) in a cubic field surrounded by telluride ions as estimated to be 1570 × 10 -4.