Magnetic Properties of the Multiferroic Compounds Eu1-Xyxmno3 (X=0.2 and 0.3)

Magnetic properties of multiferroic Eu1-xYxMnO3 with x = 0.2, 0.3 were studied by μSR and Mossbauer spectroscopy. Both compounds are known to become antiferromagnetic with Mn3+ being the only magnetic ion. We find TN = 47±0.5K for x = 0.2 and 45±0.5K for x = 0.3. Below TN three different magnetic states (AFM-1, AFM-2, AFM-3) are formed. The μSR parameters of the uppermost magnetic state (AFM-1) are alike in both compounds, and compatible with a commensurate modulated collinear spin structure. The magnetic ground state in x = 0.2 (AFM-3) is shown to be single phase. Its spectral parameters support the proposal of a cone-like spin structure, yet with incommensurate modulation. The ground state for x = 0.3 is found to have an incommensurate spiral spin structure. 151Eu Mössbauer spectroscopy measured the Eu hyperfine field induced by the Mn3+ ions. Its low value (~4T) means that mixing with higher Eu electronic states is small and that the Mn-Eu exchange coupling is weak (~0.5K). The various magnetic transitions appear as small irregularities in the temperature dependence of the hyperfine fields. The present results are discussed in terms of different published magnetic phase diagrams of Eu1-xYxMnO3.