A magnetic field sensor, including an insulating substrate and a conductive thin film deposited on the substrate. The thin film consists of a material having an extraordinary Hall coefficient, the thin film also has a resistivity and a film thickness no greater than a threshold thickness at which the resistivity is substantially equal to 150% of a bulk resistivity of the material. The sensor also includes conductors coupled to the thin film for injecting a current into the film and measuring a voltage generated across the thin film responsive to the injected current. Devices having other types of thin films, including homogeneous and non-homogeneous films, the films having enhanced extraordinary Hall coefficients, are also provided.