论文标题
缓慢冷却CO $ _ {1-x} $ cu $ _x $ mnge $（0.05 \ leq x \ leq 0.35）$的压力温度磁结构相图
Pressure-temperature magnetostructural phase diagrams of slowly cooled Co$_{1-x}$Cu$_x$MnGe $(0.05 \leq x \leq 0.35)$
论文作者
论文摘要
由ARC在Arcting Artiverere融化的Co $ $ _ {1-X} $ _ {1-x} $ cu $ _x $ mnge（$ x = 0.05、0.10、0.15、0.22 $和0.35），在1123 k下，由Arc熔化在氩气氛下进行，并在1123 K下进行了熔化。已经通过粉末X射线衍射（在温度的功能）和AC磁性测量（温度的功能和高达12 kbar的施加的静水压力）中研究了样品。根据实验数据，已确定$（p，t）$相图。 For the low Cu content ($x=0.05$, 0.10 and 0.15), the compounds show a martensitic transition between the low-temperature orthorhombic crystal structure of the TiNiSi-type (space group: $Pnma$) and the high-temperature hexagonal structure of the Ni$_2$In-type (space group: $P6_3/mmc$).对于高CU含量（$ x = 0.22 $和0.35），仅观察到六边形结构。所有化合物均以温度降低（如果$ x = 0.22 $通过中间反铁磁相$ x = 0.22 $）进行过渡到铁磁状态。在中间压力范围内（6 kbar $ \ le p \ le p \ le 8 $ kbar），para-到铁磁过渡与马氏体完全耦合为$ x = 0.05 $。在环境压力下，观察到$ x = 0.10 $的部分磁结构耦合。环境压力下的居里温度从313 K降低，以$ x = 0.05 $（在正交相中）至剩余化合物（在六边形相中）的约250 k。对于Co $ _ {0.85} $ CU $ _ {0.15} $ MNGE化合物，使用Clausius-Clapeyron方程计算了与Martensitic Transition关联的熵更改。
Polycrystalline samples of Co$_{1-x}$Cu$_x$MnGe ($x=0.05, 0.10, 0.15, 0.22$ and 0.35), prepared by arc melting under argon atmosphere, have been annealed at 1123 K with final furnace cooling. The samples have been investigated by powder X-ray diffraction (in function of temperature) and ac magnetic measurements (in function of temperature and applied hydrostatic pressure up to 12 kbar). On the basis of the experimental data, the $(p,T)$ phase diagrams have been determined. For the low Cu content ($x=0.05$, 0.10 and 0.15), the compounds show a martensitic transition between the low-temperature orthorhombic crystal structure of the TiNiSi-type (space group: $Pnma$) and the high-temperature hexagonal structure of the Ni$_2$In-type (space group: $P6_3/mmc$). For the high Cu content ($x=0.22$ and 0.35) only the hexagonal structure is observed. All compounds undergo a transition from para- to ferromagnetic state with decreasing temperature (in case of $x=0.22$ through an intermediate antiferromagnetic phase). The para- to ferromagnetic transition is fully coupled with the martensitic one for $x=0.05$ at the intermediate pressure range (6 kbar $\le p \le 8$ kbar). Partial magnetostructural coupling is observed for $x=0.10$ at ambient pressure. The Curie temperature at ambient pressure decreases from 313 K for $x=0.05$ (in the orthorhombic phase) to about 250 K for the remaining compounds (in the hexagonal phase). For the Co$_{0.85}$Cu$_{0.15}$MnGe compound, entropy change associated with the martensitic transition has been calculated using Clausius-Clapeyron equation.
