Enhanced multiferroicity of Ho0.95Co0.05Fe0.95Ti0.05O3 by co-doping in HoFeO3 nanoparticle system

Abstract

Nanocrystalline HoFeO3 is a potential multiferroic and will be more useful if its multiferroicity can be enhanced by improving the magnetic and electric ordering. In this regard, co-doping with Co and Ti, was considered in HoFeO3 (HFO) to enhance its magneto-electric behavior and thus synthesize a new monophasic multiferroic, Ho0.95Co0.05Fe0.95Ti0.05O3 (HCFTO). Both the pristine and doped HFO nanoparticles were synthesized in sol–gel route. Rietveld analyses of X-ray diffractograms, confirmed the formation of pure orthorhombic (Pnma) phase of both bare and doped HFO. Presence of the canted antiferromagnetism of bare HFO at room-temperature with antiferromagnetic transition at ∼ 637 K was confirmed in susceptibility vs. temperature variation and by the nature of MH loops. Interestingly, substantial enhancement of magnetism was observed in HCFTO compared to that of bare one, where the room-temperature maximum magnetization is enhanced by 73%. Dielectric strength of HFO (∼48) is also enhanced highly (∼3.4 times) in HCFTO (∼165), and the loss factor is lowered to nearly half. Current density vs. electric field (J-E) curve suggests the presence of polarization at room temperature with negligible leakage loss. Lower leakage loss of HCFTO indicates better multiferroicity than HFO. Direct measurement of ferroelectric loop shows the room-temperature ferroelectricity of bare HFO (Pmax ∼ 0.0041 µc/cm2) well improved (∼1.5 times) in the doped HCFTO (Pmax ∼ 0.0061 µc/cm2) with lower hysteresis loss. Room-temperature magnetoelectric coupling measurements, shows a high value (∼2.47%) of magnetocapacitance in the doped system, which is much higher (∼4.94 times) than the bare one (∼0.5%). All these properties of the sample clearly confirm the co-doping in the HoFeO3 nanoparticle system results in a considerable improvement in its magnetoelectric behavior, and this co-doped Ho0.95Co0.05Fe0.95Ti0.05O3 system can be a promising and potential magnetoelectric multiferroic for device applications.