151Eu-Mössbauer study of complex magnetism in Eu2PdSi3: Effect of Eu2+ substitution by Y3+ and of high pressure

With 151Eu-Mössbauer spectroscopy and other methods the complex magnetic properties of Eu2PdSi3, arising from the two crystallographically different lattice sites of the Eu2+ ions, have been already studied. Here we study the impact of magnetic dilution of the magnetic Eu2+ sites by non-magnetic Y3+ ions. A previous specific heat study has found reduced magnetic ordering temperatures with strong indication of disorder effects like in magnetic spin glasses. Here we provide from 151Eu-Mössbauer spectroscopy detailed information of the impact of Y3+ substitution on the magnetic properties of the two lattice sites, well distinguishable in the 151Eu-spectra. Since the substitution of the larger Eu2+ ions by the smaller Y3+ ions is connected with a lattice contraction, we also applied high pressure to the Eu2PdSi3 sample and observed drastic changes in the magnetic properties originating from a valence transition towards Eu3+ for one of the Eu sites.