Magnetic and transport properties of EuNi(Si1-xGex)3 compounds

The magnetization M, electrical resistivity rho, thermopower S and specific heat C of EuNi(Si1-xGex)(3) compounds have been measured at temperatures from 2 to 300 K. For the compounds of EuNi(Si1-xGex)(3), we obtained an effective magnetic moment of mu(eff) approximate to 7.7 mu(B), which is close to the divalent Eu value of mu(eff) = 7.94 mu(B). All compounds of EuNi(Si1-xGex)(3) order antiferromagnetically. The Neel temperature T-N decreases monotonously with increasing the Ge concentration x from T-N=49 K for EuNiSi3 to T-N=14 K for EuNiGe3. In the low temperature region below T-N, anomalies corresponding to an additional magnetic phase transition into ferromagnetic state for compounds with x < 0.3, and into another antiferromagnetic for x > 0.3 were observed. The Curie temperature T-C rapidly decreases with increasing x and vanishes at x approximate to 0.3. It is found that the magnetic phase transition temperatures of T-N and T-C in EuNi(Si1-xGex)(3) are strongly connected with the change of volume induced by the atomic substitution of Si by Ge.