Eu-151 Mossbauer and magnetic studies on magnetic superconductor EuSr2Ru1-xCu2+xO8 (-0.1 <= x <= 0.25)

Abstract

Magnetic and Eu-151 Mossbauer studies have been carried out on the ruthenocuprate magnetic superconductors, EuSr2Ru1-xCu2+xO8 (-0.1 <= x <= 0.25). The magnetic ordering temperature (T-M) decreases from 135K for x=0.0 to 125K for x= 0.25 and the superconducting transition temperature increases from 19 K (onset for x = 0.0) to 33 K (x = 0.1). The compounds with x < 0 do not show superconductivity down to 2K but show an increase in T-M. The Eu-151 Mossbauer studies show that the Eu ions are in 3 + (4f(6), J = 0) and hence in the nonmagnetic state in these compounds. The observation of a broadening in the Eu-151 Mossbauer absorption spectra below the magnetic ordering temperature indicates a small transferred magnetic hyperfine field at the Eu site. (c) 2006 Elsevier B.V. All rights reserved.