Development of a Cantilever Magnetometer for Pulsed Magnetic Fields

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9704025 Naughton A highly sensitive cantilever magnetometer will be developed for use in pulsed magnetic fields. It is anticipated that this device will achieve a sensitivity of order 10-12 Am2 (10-9 emu) in fields up to 100T, thus exceeding the sensitivity of conventional detection methods by 2 to 3 orders of magnitude. The motivation for this project is the thermodynamic study of physical phenomena in the highest available magnetic fields, which are now obtained only in transient, pulsed fields of 10-2 to 1 second duration. At the present time, experiments in pulsed fields are restricted to studies of magnetotransport, magneto- optics, and magnetic susceptibility. For the latter, an inductive method is usually employed, wherein a voltage proportional to the derivative of the magnetic moment with respect to magnetic field is induced in a multi-turn coil. If one integrates this susceptibility signal AC=dm/dH, one obtains information about the magnetic moment m, with typical sensitivity to moment of 10-8 to 10-9 Am2, or 10-5 to 10-6 emu. With the successful development of a cantilever magnetometer for the pulsed field regime, a very significant improvement over this inductance method can be realized. %%% In this project, we will design, fabricate and test a variety of cantilever devices configured especially for use in long (~10-1 s) and short (~10-2 s) pulse magnetic fields. A low field pulse system will be assembled for local temporal characterization of the new devices, with full characterization taking place at the National High Magnetic Field Laboratory's Pulsed Field Facility at Los Alamos National Laboratory. If this projects succeeds, it will significantly enhance the measurement capabilities of a large and growing number of investigators working with pulsed magnetic fields, by making sensitive magnetometry an accessible technique to a variety of physical systems in fields approaching 100T. Upon successful completion of the project, t he new devices will be made available to users at the NHMFL @ LANL. It therefore has the potential to benefit many researchers in the condensed matter sciences. In addition, there is significant potential for the transfer of this technology to industry. ***