Magnetic state of Ce in thin layers

We have fabricated Ce/Ta multilayers under ultrahigh vacuum to investigate the magnetic state of Ce in thin layers. The magnetization, electrical resistivity, and Hall effect have been measured for Ce layer thicknesses between 5 and 100 {}. Results of x-ray analysis indicate that Ce atoms crystallize as bulk Ce for dCe=100 {}, and are amorphous for dCe{}15 {}. For dCe=100 {}, the Ce {γ}-{α} transition observed in the resistivity and reduced magnetization at 2 K suggest the stabilization of {α}-phase Ce at low temperatures. For dCe{}15 {}, in contrast, the magnetic susceptibility and extraordinary Hall effect indicate the existence of magnetic Ce down to 1 K. We speculate that the transition to the nonmagnetic state of Ce at low temperatures for dCe{}15 {} is prevented by the amorphous structure. {} 1996 The American Physical Society.