OSCILLATORY METALLIC FIELD-EFFECT AND SURFACE MAGNETOELASTICITY IN THIN FERROMAGNETIC-FILMS

The metallic field effect is the change of surface conductance linear with electrostatic surface charge q. In thin Permalloy films this signal is sensitive to the direction and magnitude H of an applied magnetic field, showing an overall 4dependence for an in-plane field, and varying as 1H. Comparison with an analogous bulk signal proportional to q2 indicates that the linear signal originates in the magnetoconductivity modulation of a thin surface layer caused by interfacial stresses linear in q. Detailed interpretation of the data in terms of this model allows determination of the magnetic properties of the surface layer. The interfacial stresses deduced from the data agree with theoretical estimates. © 1979 The American Physical Society.