Spin-glass behavior in mechanically milled crystalline GdN

Concentrated spin-glass behavior is discovered in a mechanically milled crystalline compound GdN. We report on measurements of magnetic relaxation and both ac and de magnetic susceptibility at temperatures between 2 and 300 K in a magnetic field up to 5 T. Both ac and de magnetic susceptibility measurements show a peak at freezing temperatures T-f that strongly depends on the frequency and amplitude of the applied magnetic field. The magnetic relaxation measurement shows a slow decay of the remanent magnetization with time below T-f, which is well described by an exponential function in a long time scale and a reciprocal proportion function in a short time scale. The results strongly suggest that spin-glass behaviors exist in mechanically milled crystalline compound GdN with the magnetic element as high as 50 at. %.