Observation of large Hall sensitivity in thin Fe–Ge amorphous composite films.

Amorphous FexGe1-x films with different metal volume fractions (0.40<x<1.00) and film thicknesses 4–300 nm were fabricated by a cosputtering method. Magnetic and magnetotransport measurements indicated that the Fe–Ge films are ferromagnetic even above room temperature. A Hall sensitivity as large as 82 V/AT was obtained in the Fe0.67Ge0.33 film with a thickness of 4.1 nm. More importantly, it was found that the Hall sensitivity does not depend on the temperature in the temperature range of 50–300 K. In addition, the Hall resistance depends linearly on the magnetic field within the range of -2.5–2.5 kOe. This linear dependence, the larger sensitivity, and its temperature independence indicate that Fe–Ge films are potential material candidates for field sensors in a very broad temperature range. [ABSTRACT FROM AUTHOR]