Enhanced magnetization and reduced leakage current by Zr substitution in multiferroic ScMnO3

Abstract

Despite numerous attempts of electron doping in different manganites (RMnO3, R=rare earth), successful reports are scarce in the literature till date. In this paper, we have synthesized a series of phase-pure electron doped multiferroic compound Sc1−xZrxMnO3 (x=0, 0.05, 0.1, and 0.2) and evaluated the effect of doping on structural properties, oxidation states of cations, DC magnetization, heat capacity, resistivity, dielectric behaviour and ferroelectricity in the material. The presence of Zr4+ and mixed valence state of Mn comprising of Mn2+ and Mn3+ ions are confirmed using X-ray photoelectron spectroscopy. All these samples exhibit antiferromagnetic ordering; as Zr4+ content increases, antiferromagnetic ordering gradually diminishes while shifting to low temperatures. Additionally, ferromagnetic-like interaction develops in doped systems which gives rise to hysteresis in isothermal magnetization loops with greatly enhanced magnetization in comparison to pure antiferromagnetic nature of x=0 i.e. ScMnO3. Interestingly, even with zero magnetic moment of Sc3+, Schottky-like anomaly is observed at 5K in heat capacity data of samples with x=0.1 and 0.2, a result that we attribute to the highly resistive nature of doped samples. Moreover, while measuring ferroelectric hysteresis loops, we observe a significant reduction of leakage current in doped sample (x=0.2) compared to pure ScMnO3. Additionally, the compound x=0.2 shows improved dielectric and ferroelectric behaviour. It is proposed that doping of Zr4+ compensates for the cation deficiency and consequently eliminates the inherent oxygen vacancies by charge compensation.