Magnetic and dielectric properties of YbFe2−xMnxO4 (0⩽x⩽1)

We have investigated the magnetic and dielectric properties of YbFe2−xMnxO4 (0⩽x⩽1), which is an Fe-site-substituted system of new multiferroic oxides RFe2O4 (R=Y, Ho–Lu). X-ray diffraction measurements show that a solid solution is formed between YbFe2O4 (x=0) and YbFeMnO4 (x=1) for 0⩽x⩽1, whereas only compounds with x=1 (i.e., RM1M2O4; M1 and M2=trivalent and divalent cations, respectively) have been known for the Fe-site substitution in RFe2O4. The valence of the Mn ion is determined to be ∼2+, consistently with the suppression of low-temperature magnetization by the Mn substitution. The magnetic transition temperature (TN) and the dielectric constant (ε′) decrease monotonically with increasing x. This result plausibly confirms that the magnetic and dielectric properties in oxides isostructural with RFe2O4 are governed by the electron transfer between Fe-site ions, unlike ordinary ferroelectrics and dielectrics, in which the ionic displacement plays a key role. The possibility for application is briefly discussed as well.