Impurity nearest-neighbor distances studied by extended x-ray absorption fine structure: Application to electron-spin resonance

The local environment around Pr as a magnetic impurity in ErSb solid solutions was investigated by extended x-ray absorption fine structure measurements on ErₓPr_1-xSb(x=1,0.95,0.90). The nearest-neighbor distances around the Pr ion were found to be nearly the same as in pure PrSb, almost independent of the Pr concentration in the alloys. Thus, the usual assumption used in electron-spin-resonance measurements---that the impurity nearest-neighbor distance is the same as that of the host---is incorrect.