Electron Doping Effect on AeCo2As2 (Ae = Ca, Sr and Ba)

We synthesized polycrystalline samples of solid solutions Ae(Co1-xNix)2As2 (Ae = Ca, Sr and Ba) and measured their magnetization. In the case of SrCo2As2, antiferromagnetic ordering was induced by slight substitution of Ni for Co in a range of x with “uncollapsed tetragonal” crystal structure. In the case of BaCo2As2, magnetic ordering was not induced in all the x range although electronic states come to be close to quantum critical point of magnetic ordering at about x = 0.15. Such magnetic enhancement by Ni substitution for Co indicates that the Fermi energy of Co122 is slightly lower than other compounds with CoAs layers.