We have studied the effects of substituting nonmagnetic Ga3+ for Mn3+ on dielectric and magnetic properties in multiferroic YMn 2O5. Upon Ga substitution, whereby only the Mn3 + ions are selectively replaced, the commensurate magnetic phase eventually disappeared owing to the disconnection of the magnetic interaction between Mn3+ and Mn4+ ions. In contrast, the low-temperature incommensurate magnetic phase is hardly affected by Ga substitution. Precise crystal structure analyses of Ga-substituted YMn 2O5 have revealed that the bonds between Mn ions along the ab plane changed markedly with increasing Ga concentration, while those along the c axis did not change at all. This indicates that the magnetic interactions along the ab plane were altered dramatically, while those along the c axis were robust against Ga substitution. From the dielectric and magnetic phase diagrams as a function of Ga substitution, we conclude that the electric polarization is predominantly induced by exchange-striction in the commensurate magnetic phase, and by an inverse Dzyaloshinskii-Moriya interaction in the incommensurate phase.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2013 Mar 29|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics