抄録
Magnetic-superconductor Y9Co7 has been investigated from a magnetization measurement in the temperature range between 0.5 K and 420 K and in the magnetic fields H from ∼2 Oe to 70 kOe. The magnetization M can be expressed in a form of H⁄M=a+bM2+cM4 up to 70 kOe at 0.5 K. Above 2.2 K (superconducting transition temperature) and in a limited region of magnetization, the magnetization is expressed in a form of H⁄M=a+bM2. The spontaneous magnetization Ms varies with temperature T as Ms2∝(Tm4⁄3−T4⁄3), where Tm is the ferromagnetic transition temperature of 4.2 K. The magnetic moment extrapolated to zero temperature and zero field is 0.09 μB/Y9Co7. These behaviors indicate Y9Co7 to be a very weak itinerant-electron ferromagnet. The magnetization curve in a superconducting state suggests a very hard type II superconductor or an inhomogeneous state.
