Long-Range Antiferromagnetic Ordering in B-Site Ordered Double Perovskite Ca2ScOsO6.
Long-Range Antiferromagnetic Ordering in B-Site Ordered Double Perovskite Ca2ScOsO6.
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DOI：
10.1021/acs.inorgchem.5b02630
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发表时间：
2016-02
影响因子：
4.6
通讯作者：
David D. Russell;Abbey J. Neer;B. Melot;S. Derakhshan
中科院分区：
文献类型：
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作者：
David D. Russell;Abbey J. Neer;B. Melot;S. Derakhshan
成功合成了一种新的B位有序双钙钛矿结构的锇基化合物，其化学组成为Ca 2ScOsO 6。用粉末X射线衍射法测定了标题化合物的晶体结构，属单斜晶系P21/n空间群，晶胞常数a = 5.4716（1）B = 5.6165（1），c = 7.8168（1），β = 89.889（2）°。随温度变化的磁化率数据表明，该化合物的S =（3）/2结构在169 K发生了反铁磁转变。将高温磁化率数据（100-300 K）与Currie-Weisse行为拟合得到C = 1.734 emu·K/mol（μeff = 3.72 bohr磁子）和θ = -341 K，这表明主要的反铁磁相互作用。与温度相关的比热测量在69 K时表现出λ形异常，这与自旋的长程有序一致。由于反铁磁有序磁性离子的三角形排列，该系统表现出一定程度的几何磁阻挫（GMF），但不强烈。自旋二聚体分析，采用扩展的休克尔理论，揭示了一个占主导地位的交换相互作用存在（沿着在钙钛矿层的a晶轴），这违反了GMF的完美条件。
A new Os-based B-site ordered double perovskite with the chemical composition of Ca2ScOsO6 was successfully synthesized. The crystal structure of the title compound was determined by employing the powder X-ray diffraction method and was found to crystallize in the monoclinic P21/n space group with the cell constants of a = 5.4716(1) Å, b = 5.6165(1) Å, c = 7.8168 (1) Å, and β = 89.889 (2)°. The temperature-dependent magnetic susceptibility data suggest that this novel S = (3)/2 compound undergoes an antiferromagnetic transition at ∼ 69 K. Fitting the high-temperature susceptibility data (100-300 K) to Currie-Weisse behavior showed C = 1.734 emu·K/mol (μeff = 3.72 bohr magnetons) and θ = -341 K, which is indicative of dominant antiferromagnetic interactions. Temperature-dependent specific heat measurements exhibit a λ shape anomaly at 69 K, which is consistent with a long-range ordering of the spins. Because of a triangular arrangement of antiferromagnetically ordered magnetic ions, the system exhibits some degree of geometric magnetic frustration (GMF), but not strongly. Spin-dimer analysis, employing extended Hückel theory, reveals that a dominant exchange interaction exists (along the a crystallographic axis in perovskite layer), which violates the perfect condition for GMF.