Observation of conduction electron spin resonance in the neodymium cerium copper oxide (Nd1.85Ce0.15CuO4-y) superconductor

Normal and superconducting Nd{sub 2{minus}x}Ce{sub x}CuO{sub 4{minus}y} (x = 0.00, 0.15) compounds have been studied by electron spin resonance (ESR). In contrast to previous reports that the high-temperature superconducting oxocuprate compounds are ESR silent, a conduction ESR (CESR) signal has been observed in the superconducting Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4{minus}y} compound. The temperature dependence of the CESR signal intensity, g value, and line width are consistent with a two-dimensional spin structure in Nd{sub 1.85}Ce{sub 0.15}CuO{sub 4{minus}y}. A possible reason for the lack of a CESR signal in other high-temperature superconducting systems is that they have more efficient spin-lattice relaxation which is associated with CESR lines too broad to be detected. 14 refs., 4 figs.