ABSTRACTWe have studied the electrical transport behavior of sputter deposited Nix(SiO2)100−x thin films between room temperature and 100 mK and, at selected temperatures, in applied magnetic fields up to 6 T. As the Ni concentration x is reduced, the resistivity increases systematically. At a Ni concentration (nominal) of about x–70 atomic percent (38 volume percent) the room temperature coefficient of resistivity changes sign. For Ni concentrations greater than 70 percent the resistance first decreases with temperature then increases logarithmically at, low temperatures. This increase becomes smaller and the resistivity minimum moves to progressively lower temperatures as the Ni concentration increases. In films with less than x–70 percent Ni, the resistivity has a temperature dependence of the form ρ(T)–ρo exp \(To/T)α] between room temperature and about 5 K. The exponent a is about 1/2 and To increases with decreasing Ni content. Below 1 K, however, the resistivity increases much less rapidly, with a temperature dependence independent of Ni concentration. In all films the magnetoresistance is small and negative.
Resistivity Minimum in Highly Frustrated Itinerant Magnets
