Electron spin resonance study of the LaIn3-xSnx superconducting system

The LaIn3-xSnx alloy system is composed of superconducting Pauli paramagnets. For LaIn3 the superconducting critical temperature Tc is approximately 0.7 K and it shows an oscillatory dependence as a function of Sn substitution, presenting its highest value Tc ≈ 6.4 K for the LaSn3 end member. The superconducting state of these materials was characterized as being of the conventional type. We report our results for Gd3+ electron spin resonance measurements in the LaIn3-xSnx compounds as a function of x. We show that the effective exchange interaction parameter Jfs between the Gd3+ 4f local moment and the s-like conduction electrons is almost unchanged by Sn substitution and observe microscopically that LaSn3 is a conventional superconductor. (paper)