Ferroelectricity Induced by Cations of Nonequivalent Spins Disordered in the Weakly Ferromagnetic Perovskites,YCr1鈥?i>xMxO3 (M = Fe or Mn)

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• 作者：B. Rajeswaran ; P. Mandal ; Rana Saha ; E. Suard ; A. Sundaresan ; C. N. R. Rao
• 刊名：Chemistry of Materials
• 出版年：2012
• 出版时间：September 25, 2012
• 年：2012
• 卷：24
• 期：18
• 页码：3591-3595
• 全文大小：318K
• 年卷期：v.24,no.18(September 25, 2012)
• ISSN：1520-5002

文摘

Rare-earth orthochromites, RCrO₃ (R = rare-earth and Y) with magnetic R-ions are reported to exhibit ferroelectricity at the magnetic ordering temperature of Cr³⁺-ions (Rajeswaran, B.; Khomskii, D. I.; Zvezdin, A. K.; Sundaresan, A.; Rao, C. N. R. arXiv2012, 1201, 0826v1 ). Interestingly, we observe ferroelectricity at the N茅el temperature of orthochromites containing a nonmagnetic R-ion (Y) upon introducing cation-disorder at the Cr-site by incorporation of another magnetic ion of nonequivalent spin. For example, the weakly ferromagnetic perovskite, YCr_0.5Fe_0.5O₃, where the Cr³⁺ (S = 3/2) and Fe³⁺ (S = 5/2) ions at the B-site are disordered, exhibits ferroelectricity at T_N = 260 K. Ferroelectricity is observed not only when the relative proportions of Fe³⁺ and Cr³⁺ ions as in YCr_1鈥?i>xFe_xO₃ are varied but also when Y³⁺ ions are replaced by other nonmagnetic R-ion and the transition metal ions changed as in YCr_1鈥?i>xMn_xO₃. While the local polarization cancels out in the weakly ferromagnetic YMO₃ (M = Cr and Fe), a nonzero polarization in these materials seem to arise due to disordered transition metal ions of nonequivalent spins.

Keywords:

ferroelectricity; cation disorder; weak ferromagnetism; multiferroics; orthochromites