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arXiv 1306.5182cond-mat.str-elcond-mat.mtrl-scicond-mat.supr-con
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新型BaMnPnF(Pn = As,Sb,Bi)的晶体、磁性、电子结构和性质

Crystal, magnetic, and electronic structures, and properties of new BaMnPnF (Pn = As, Sb, Bi)

Bayrammurad Saparov, David J. Singh, V. Ovidiu Garlea, Athena S. Sefat

摘要:

通过BaF 2与元素的化学计量反应,合成了新的氟磷属化合物BaMnPnF(Pn = As,Sb,Bi).单晶和粉末X射线衍射结果表明,化合物属于四方晶系P4/nmm(No.129,Z = 2)空间群,具有ZrCuSiAs型结构。电阻率测试结果表明,Pn = As,Sb和Bi为半导体,带隙分别为Eg = 0.73eV,Eg = 0.48eV和Eg = 0.0 0 3eV.粉末中子衍射结果表明,在T_N = 338(1)K和T_N = 272(1)K以下,Pn = As和Pn = Sb的样品均具有G型反铁磁有序结构,磁化率随温度的升高而增大。密度泛函计算还发现了具有强的面内和弱的面外交换耦合的半导体反铁磁化合物,这可能导致在T N以上的非Curie Weiss行为。锰与磷属元素之间存在较强的共价性。由中子衍射实验得到的有序磁矩在4K时为3.65(5)μB/Mn(Pn = As)和3.66(3)μB/Mn(Pn = Sb)。

英文摘要:

New fluoropnictides BaMnPnF with Pn = As, Sb, Bi, are synthesized by stoichiometric reaction of elements with BaF\_2. The compounds crystallize in the tetragonal P4/nmm (No. 129, Z = 2) space group, with the ZrCuSiAs-type structure, as indicated by single crystal and powder X-ray diffraction results. Electrical resistivity results indicate that Pn = As, Sb, and Bi are semiconductors with band gaps of E\_g = 0.73 eV, E\_g = 0.48 eV and E\_g = 0.003 eV, respectively. Powder neutron diffraction reveals a G-type antiferromagnetic order below T\_N = 338(1) K for Pn = As, and below T\_N = 272(1) K for Pn = Sb. Magnetic susceptibility increases with temperature above 100 K for all the materials. Density functional calculations also find semiconducting antiferromagnetic compounds with strong in-plane and weaker out-of-plane exchange coupling that may result in non-Curie Weiss behavior above T\_N. There is strong covalency between Mn and pnictogen elements. The ordered magnetic moments are 3.65(5) μB/Mn for Pn = As, and 3.66(3) μB/Mn for Pn = Sb at 4 K, as refined from neutron diffraction experiments.

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