Modulated multiferroicity of Cr-doped orthorhombic polycrystalline YMnO3

We synthesize a series of orthorhombic polycrystalline YMn(1-x)CrxO(3) (o-YMCO, x < 0.3) samples using high-pressure sintering, and investigate the multiferroicity by various characterization techniques. It is identified that Cr doping remarkably enhances the ferromagnetism, and the ferroelectric polarization is also significantly modulated. The enhanced ferromagnetism is argued to originate from the ferromagnetic interactions between neighbouring Cr3+ spins and Mn3+ spins. While the microscopic mechanism for polarization generation remains to be clarified, it may be argued, based on the response of polarization against external magnetic field, that Cr doping induces a partial transition from the symmetric exchange striction mechanism in o-YMnO3 to the asymmetric exchange striction mechanism in o-YMCO for ferroelectricity generation.