Thin Film Shielding Alloy for Magnetic Field Modulation

Thin Film Shielding Alloy for Magnetic Field Modulation in an Integrated Nano Mechanically-Regulated Atomic Clock Carolyn D. White 5109 Etcheverry Hall University of California, Berkeley, CA 94720 -1740 TEL: (510) 643 -1099 FAX: (510) 643 -6637 whitecd@newton. berkeley. edu Lenslet Array Rb 87 Vapor Cell Photovoltaic Array Rb 85 Lamp Drive Electronics Ni 63 Radiation Source Resonator Array Permanent Magnet Advisor: Prof. Albert P. Pisano Project Number: APP 58 DARPA MTO CSAC BSAC © 2004 Spring IAB. Confidential Information. Not to be made public without permission Sample from UC Regents.

Background w An integrated, nano mechanically-regulated atomic clock will be designed, fabricated and evaluated to reduce the size, mass, and power consumption and enable use on portable platforms. This particular project will specifically develop a thin film shielding alloy for modulation of a magnetic field. w In the resonance cell, an array of shielding resonators modulate a constant magnetic field to provide magnetic flux reversals at 6. 835 GHz using a mechanical resonance of only 3. 4175 GHz. n Gaps allow the magnetic field to leak into the resonance cell n If a plate is moved, the flux intensity in the surrounding area is changed. n If moved at a certain frequency, the magnetic field would vary with that frequency. BSAC © 2004 Spring IAB. Confidential Information. Not to be made public without permission from UC Regents. 2

Material Characterization Epox y Si 02 Ni. Fe ~9 nm w TEM image of evaporated Ni. Fe film on silicon wafer with native oxide. w Thickness is ~ 9 nm. w EDX of Ni. Fe film: wt% at% Fe: 17. 32 18. 04 Ni: 82. 68 81. 96 Si wafe r BSAC © 2004 Spring IAB. Confidential Information. Not to be made public without permission from UC Regents. 3

Material Characterization Preliminary Results For Sputtered Ni. Fe. Cu. Mo w Low relative permeability ~ 3. 2 x 10 -4 (vs. 3. 7 x 103) Slope w Lower saturation flux density ~ 0. 3 T (vs. 0. 5 T) Y-axis intercept at saturation w w Order of Magnitude Higher in Scale Mumetal (Ni. Fe. Cu. Mo) films have been sputtered on silicon substrates and initial data show less desirable magnetic properties. Will try sputtered Ni. Fe films but may stay with thermally evaporated film. BSAC © 2004 Spring IAB. Confidential Information. Not to be made public without permission from UC Regents. 4