Eur. Phys. J. B (2013) 86: 333
https://doi.org/10.1140/epjb/e2013-40409-4

Regular Article

¹⁵¹Eu Mössbauer study of multiferroic Eu_0.75Y_0.25MnO₃

¹ Istituto dei Sistemi Complessi – CNR, Via Madonna del Piano 10, 50019 Sesto Fiorentino (FI), Italy
² Dipartimento di Fisica – Università di Firenze and CNISM, Via Sansone 1, 50019 Sesto Fiorentino (FI), Italy

^a e-mail: marco.lantieri@isc.cnr.it

Received: 17 April 2013
Received in final form: 7 June 2013
Published online: 24 July 2013

Abstract

We are herewith reporting the ¹⁵¹Eu Mössbauer spectra collected on a polycrystalline powder sample of Eu_0.75Y_0.25MnO₃ from 15 K to room temperature. All the spectra consist of a single line, whose shape and related sample thickness are dependent on the temperature T. The thermal trend of the mean square displacement of Eu ion, obtained from the spectra analysis, clearly reveals a large low-temperature anharmonicity and in concomitance with the onset of the magnetic ordering consists in a linear strong decrease interrupted by two narrow wells at 29.5 K and 40 K. This behavior is interpreted in connection with the transfer of spectral weight from the 120 cm^-1 optical phonon to the electromagnonic modes. The T-trend of the central shift shows that Eu³⁺ electronic ground state in the magnetically ordered phase differs from the one in the paramagnetic state. Finally, the temperature dependence of the hyperfine field under T_N gives a contribution to interpret some controversial features regarding the phase-diagram.