Single crystals of Ba(Fe_(1-x)Mn_x)_2As_2, 0<x<0.148, have been grown and characterized by structural, magnetic, electrical transport and thermopower measurements. Although growths of single crystals of Ba(Fe_(1-x)Mn_x)_2As_2 for the full 0<=x<=1 range were made, we find evidence for phase separation (associated with some form of immiscibility) starting for x>0.1-0.2. Our measurements show that whereas the structural/magnetic phase transition found in pure BaFe_2As_2 at 134 K is initially suppressed by Mn substitution, superconductivity is not observed at any substitution level. Although the effect of hydrostatic pressure up to 20 kbar in the parent BaFe_2As_2 compound is to suppress the structural/magnetic transition at the approximate rate of 0.9 K/kbar, the effects of pressure and Mn substitution in the x=0.102 compound are not cumulative. Phase diagrams of transition temperature versus substitution concentration, x, based on electrical transport, magnetization and thermopower measurements have been constructed and compared to those of the Ba(Fe_(1-x)TM_x)_2As_2 (TM=Co and Cr) series.
Magnetic form factor analysis on detwinned single crystal of BaFe$_2$As$_2$
我们对铁基超导体的母体化合物BaFe $_2$ As $_2$单晶进行了12 K的中子衍射测量。为了研究反铁磁相中磁形状因子的面内各向异性，测量中使用了去孪晶的单晶。磁结构因子和磁形状因子可以用自旋密度来解释，自旋密度由占40%的$3d_{yz}$电子和占15%的其他四个$3d$轨道的电子组成.这种各向异性磁形状因子与铁基超导体母体化合物的反铁磁相中观察到的各向异性磁行为定性一致。
Anomalous local magnetic field distribution and strong pinning in CaFe1.94Co0.06As2 single crystals
CaFe1.94Co0.06As2单晶的磁光成像显示超导体的迈斯纳区域内的异常剩余磁化。非常规的形状的局部磁化磁滞回线表明混合物的超导和磁性分数控制的响应。在超导转变温度附近，局部磁场超过所施加的磁场，导致抗磁性到正磁化转变。在局部磁场分布中观察到的异常伴随着在CaFe 1.94 Co 0.06 As 2单晶中增强的体钉扎。我们提出我们的结果表明超导性和磁关联共存。
Absence of a Competition between Magnetism and Superconductivity in the Layered Nickel Borocarbides: Common Correlation Tc with Crystal Chemical Parameters for Magnetic and Nonmagnetic Compounds
