Electrical and magnetic properties of amorphous W-Mn-O films.

The influence of the metal-insulator transition on the spin- glass transition in W-Mn alloys was studied by measuring the magnetic properties of W-Mn-O films as a function of oxygen content for various Mn concentrations. The metal-insulator transtion was determined by the electrical resistivity of WO sub x films with 0= x = 3. Contrary to the (MnSi)O sub x alloys where the spin-glass transition exists in both the metallic (x ~ 1) and the insulating state (1 ~ x ~ 3.6), the spin glass transition in (W-Mn)O sub x alloys disappears for x >= 1.25. This disappearance does not seemed to be linked directly to the metal-insulator transition, since alloys with resistivities in excess of 10 sup 3 muOMEGAcm still display a spin-glass transition, but is more likely dependent on a critical oxygen concentration which changes the host from W to WO sub 1-1.25.