Electron spin relaxation near a micron-size ferromagnet.
Magnetic resonance force microscopy was used to study the behavior of small ensembles of unpaired electron spins in silica near a micrometer-size ferromagnetic tip. Using a cantilever-driven spin manipulation protocol and a magnetic field gradient greater than 10(5) T/m, signals from as few as 100 net spins within a 20 nm thick resonant slice could be studied. A sixfold increase in the spin-lattice relaxation rate was found within 800 nm of the ferromagnet, while no effect due to silica surface proximity was detected. The results are interpreted in terms of Larmor-frequency magnetic field fluctuations emanating from the ferromagnet.
Stipe
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IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose, California 95120, USA.
Mamin
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Yannoni
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Stowe
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Kenny
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Rugar
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