XYZ on a Chip: Magnetic Nanosensors on a Chip

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9980734ClelandThe PI's have recently developed methods by which deep sub-micron-size mechanical structures, with integrated displacement-inducing and displacement-sensing elements, can be fabricated and used as practical sensors. The PI's wish to apply this technology to the development of high-frequency chip-based magnetic sensors, which in the ultimate limit will be sensitive to the behavior of individual magnetic moments. The sensors they will develop will be based on nanometer-scale, radiofrequency cantilevers, fabricated from single-crystal GaAs heterostructure substrates. GaAs is a piezoelectric material, allowing the use of both piezoresistive and piezoelectric strain sensing. The magnetic signals will emanate either from magnetic samples embedded in the sensor geometry, or from the interaction of an magnetic tip integrated in the cantilever design, which is scanned over a fixed, magnetically active sample. In the former geometry, they plan experiments to probe the physics of very small ferromagnetic and paramagnetic samples, and the mechanical detection of optically-induced electronic and nuclear magnetization. The latter geometry will allow a number of microscopy applications, probing both surface and subsurface interactions. Signals emanating from subsurface sources, such as electric currents on a buried heterostructure interface, would allow imaging on an otherwise topologically featureless sample.These sensors should be able to probe time scales approximately four orders of magnitude shorter, and magnetic volume scales approximately five orders of magnitude smaller, than the present state-of-the-art in scanned magnetic force probes and fixed torque magnetometry. These sensors should allow sensitivities of order one Bohr magneton at frequencies approaching 1 GHz. The high frequencies and small physical size scales they will thereby be able to probe will engender a number of interesting engineering and science applications.***