MICROMACHINED SILICON TORSIONAL RESONATOR FOR MAGNETIC-ANISOTROPY MEASUREMENT

A novel method for measuring the out-of-plane magnetic anisotropy of t hin films has been developed using the existing techniques of silicon micromachining. The torsion pendulum, which is commonly used to measur e the perpendicular magnetic anisotropy energy constant, K-u, is modif ied into a single crystal silicon high Q torsional resonator. This art icle describes the principle of a silicon torsional resonator, the exp erimental procedure for measuring magnetic anisotropy, and the results . The theoretical values of K-u for Terfenol-D and Metglas(R) thin fil ms were compared to the experimentally determined values and found to be within the error limits which for Metglas(C), better than 1%. The a greement is poorer, 5%-15%, for amorphous stressed Terfenol- D, since its magneto-elastic energy is less accurately known. The results show that this is a viable method for measuring the magnetic anisotropy. (C ) 1998 American Institute of Physics. [S0034-6748(98)04611-5].