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arXiv 2003.11569cond-mat.mtrl-sci
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反铁磁Mn $_{2}$ PtPd的晶体和磁性结构

Crystal and magnetic structure of antiferromagnetic Mn$_{2}$PtPd

Vivek Kumar, Manfred Reehuis, Andreas Hoser, Peter Adler, Claudia Felser

摘要:

我们用粉末X射线和中子衍射实验研究了Mn ${}_{2}$ PtPd合金的晶体结构和磁结构。该化合物被认为属于具有晶体对称性$\mathit{I}$ 4/ $\mathit{mmm}$(TiAl ${}_{3}$型)的Heusler家族.然而,在这项工作中,我们发现Pd和Pt原子是无序的,因此Mn ${}_{2}$ PtPd在具有$\mathit{P}$ 4/ $\mathit{mmm}$对称性(CuAu-I型)的$\mathit{L}$ 1 ${}_{0}$结构中结晶,如MnPt和MnPd二元合金。室温下的晶格常数为$\mathit{a}$ = 2.86 Ω和$\mathit{c}$ = 3.62 Ω。Mn ${}_{2}$ PtPd在Néel温度$\mathit{T}$ ${}_{N}$ = 866 K以下具有共线反铁磁自旋结构,其中$\mathrm{\sim}$ 4 $μ$ ${}_{B}$的Mn矩位于$\mathit{ab}$ -平面中。我们观察到$\mathit{T}$ ${}_{N}$附近的晶格参数的强烈变化。样品表现出金属行为,其中电阻率和载流子浓度分别为10 ${}^{-5}$ $Ω$ cm和10 ${}^{21}$ cm ${}^{-3}$的量级。

英文摘要:

We have investigated the crystal and magnetic structure of Mn${}_{2}$PtPd alloy using powder x-ray and neutron diffraction experiments. This compound is believed to belong to the Heusler family having crystal symmetry $\mathit{I}$4/$\mathit{mmm}$ (TiAl${}_{3}$-type). However, in this work we found that the Pd and Pt atoms are disordered and thus Mn${}_{2}$PtPd crystallizes in the $\mathit{L}$1${}_{0}$ structure having $\mathit{P}$4/$\mathit{mmm}$ symmetry (CuAu-I type) like MnPt and MnPd binary alloys. The lattice constants are $\mathit{a}$ = 2.86 Å and $\mathit{c}$ = 3.62 Å at room temperature. Mn${}_{2}$PtPd has a collinear antiferromagnetic spin structure below the Néel temperature $\mathit{T}$${}_{N}$ = 866 K, where Mn moments of $\mathrm{\sim}$4 $μ$${}_{B}$ lie in the $\mathit{ab}$-plane. We observed a strong change in the lattice parameters near $\mathit{T}$${}_{N}$. The sample exhibits metallic behaviour, where electrical resistivity and carrier concentration are of the order of 10${}^{-5}$ $Ω$ cm and 10${}^{21}$ cm${}^{-3}$, respectively.

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