ELECTRON-SPIN-RESONANCE OF GD3-STATE OF RNI2B2C (R=Y,LU)( IN THE NORMAL)

Electron spin resonance (ESR) of Gd3+ in the normal state (T>T-c) of R 1-xGdxNi2B2C (R=Y,Lu) is reported. The results show that the exchange coupling between the rare-earth localized magnetic moment and the cond uction electrons depends on the conduction electrons momentum transfer (\k(F)(in)-k(F)(out)\ = q), i.e., J(fs)(q). The temperature dependenc e of the ESR linewidth yields a value for one of the exchange paramete rs, [J(fs)(2)(q)](EF)(1/2), which is in agreement with that estimated from the slope of the initial linear decrease of T-c by the Gd3+ impur ities. These results indicate that the R1-xGdxNi2B2C (R=Y,Lu) compound s behave as conventional BCS superconductors, in agreement with previo us reports. [S0163-1829(98)02806-9].