Magnetic ordering in the new ternary stannide U3Rh4Sn13

U3Rh4Sn13 melts noncongruently and crystallizes in the cubic Yb3Rh4Sn13-type structure with a = 9.6416 A. Magnetic, electrical, specific heat measurements and a 119Sn Moessbauer spectroscopy study reveal that this stannide undergoes a magnetic transition near 17.5 K. At low temperature, U3Rh4Sn13 shows an enhanced electronic specific heat coefficient (γ0 = 0.225 J/K2U atom) as observed in magnetically ordered heavy fermions compounds. In addition below the magnetic transition temperature a broadening of the two quadrupole splitting of the Moessbauer spectrum indicates clearly the presence of a hyperfine field at the Sn sites. U3Rh4Sn13 exhibits a magnetic ordering temperature that is much higher than those already observed for similar stannides containing rare earths. (orig.)