Two-Step Antiferromagnetic Transitions and Ferroelectricity in Spin-1 Triangular-Lattice Antiferromagnetic Sr3NiTa2O9

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• 作者：Meifeng Liu ; Huimin Zhang ; Xin Huang ; Chunyang Ma ; Shuai Dong ; Jun-Ming Liu
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：March 21, 2016
• 年：2016
• 卷：55
• 期：6
• 页码：2709-2716
• 全文大小：529K
• ISSN：1520-510X

文摘

We report the low-temperature characterizations on structural, specific heat, magnetic, and ferroelectric behaviors of transition metal oxide compound Sr₃NiTa₂O₉. It is suggested that Sr₃NiTa₂O₉ is a spin-1 triangular lattice Heisenberg quantum antiferromagnet which may have weak easy-axis anisotropy. At zero magnetic field, a two-step transition sequence at T_N1 = 3.35 K and T_N2 = 2.74 K, respectively, is observed, corresponding to the up–up–down (uud) spin ordering and 120° spin ordering, respectively. The two transition points shift gradually with increasing magnetic field toward the low temperature, accompanying an evolution from the 120° spin structure (phase) to the normal oblique phases. Ferroelectricity in the 120° phase is clearly identified. The first-principles calculations confirm the 120° phase as the ground state whose ferroelectricity originates mainly from the electronic polarization.