Microcantilever torque magnetometry of thin magnetic films

Abstract

We have developed a microcantilever torque magnetometer based on a torsion-mode atomic force microscope. Thin magnetic films are deposited directly onto micromachined silicon cantilevers. We have measured hysteresis loops of iron thin films with thicknesses ranging from 1 to 40 nm and total magnetic volumes ranging from 2.2×10−11 to 8.8×10−10 cm3. The magnetic moment sensitivity is estimated to be 1.3×10−12 A m2/Hz1/2 at room temperature and ambient conditions. We expect that by operating at the cantilever torsion resonance frequency and at higher torque fields sensitivity will be improved by a factor of 100–1000.

High sensitivity detection of radio-frequency modulated magnetic moment in semiconductors

“…The development of torque magnetometry using silicon micromachined cantilevers 2 has improved the quantitative detection limit to 10 −12 Am 2 at room temperature. 3 Even higher sensitivities have been reported in miniaturized sensors typically used for spatial imaging of small particles such as the low temperature micro-SQUID 4 and micro-Hall 5 sensors. For example, a detection limit of 10 −21 Am 2 in unity bandwidth has been reported 6 for a ∼5 μm size SQUID sensor, but operating at a very low temperature of 125 mK.…”

Analysis of Frequency Locking in Optically Driven MEMS Resonators

“…An essential feature of this oscillator is that outside of a certain region of the forcing frequency, the device vibrates at a constant amplitude at its natural frequency, independent of the external modulation frequency, while inside the region, the device locks itself to the external modulation. The motivation for such a device comes from the fact that the resonant mode operation of micro and nanoscale oscillators has gained wide interest for applications such as electromechanical filters [5], amplifers, nonlinear mixers [6], [7], atomic scale imaging, scanning probe microscopes, ultrasensitive magnetometers [8], and biological and chemical sensors [9]. Since the resonant frequency of the vibrating sensor carries the information, a fixed resonant frequency limits the applicability of MEMS in many cases.…”

Anchor Loss Reduction in Resonant MEMS using MESA Structures

“…Affiliation (Electrical and Computer Engineering, Cornell University, USA.) 3. Affiliation (Applied and Engineering Physics, Cornell University USA)…”