Effect of Mn doping on magnetic and dielectric properties of YFeO₃

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• 作者：Bipul Deka ; S. Ravi ; ^{sravi@iitg.ernet.in" class="auth_mail" title="E-mail the corresponding author} ; A. Perumal ; D. Pamu
• 关键词：Mn doped YFeO3 ; Spin re-orientation ; Multiferroics ; Dielectric properties ; Nyquist plot ; Ac electrical properties
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：1323-1334
• 全文大小：2785 K

文摘

We report the magnetic and dielectric properties of single phase samples of orthorhombic YFe_1−xMn_xO₃ (x=0.0–0.3). The Néel temperature is found to decrease from 646 K for x=0–428 K for x=0.3 due to the weakening of superexchange interaction upon Mn³⁺ substitution. In addition, Mn substitution induces spin re-orientation transition and the spin re-orientation transition temperature is found to increase from 81 K for x=0.1–295 K for x=0.3. It is explained in terms of significant magnetic anisotropy introduced by the substituted Mn³⁺ ions. From the analysis of magnetization data exchange field, Dzyaloshinskii-Moriya field and canting angle were estimated and their temperature dependence in the vicinity of spin re-orientation transition temperature is studied. Study of complex impedance spectrum, dielectric constant and ac electrical conductivity in a wide range of frequency (10²–10⁶ Hz) across the Néel temperature elucidates the role played by both grains and grain boundaries in shaping the dielectric relaxation. The depressed/asymmetric semicircular shape of Nyquist plots depicts the presence of non-Debye type dielectric relaxation, which is attributed to the short-range movement of oxygen vacancies. The observed increase in dielectric constant and its loss component with increase in Mn concentration is attributed to the leakage current due to hopping of charge carriers between Fe²⁺ and Fe³⁺ sites as well as due to the movement of oxygen vacancies. An anomaly in the dielectric constant is observed for all samples in the vicinity of Néel temperature and it is attributed to the disappearance of spin canting induced improper ferroelectric order at the onset of magnetic ordering. The analysis of ac electrical conductivity spectra in terms of Jonscher’s power law suggests that the charge carriers undergo quantum mechanical tunneling between asymmetric double well potential.