AVS 47th International Symposium
    Magnetic Interfaces and Nanostructures Thursday Sessions
       Session MI+NS+NANO 6-ThM

Paper MI+NS+NANO 6-ThM3
Electron Spin Relaxation at Nanometer Length Scales Near a Ferromagnet

Thursday, October 5, 2000, 9:00 am, Room 206

Session: Nanomagnetism
Presenter: B.C. Stipe, IBM Almaden Research Center
Authors: B.C. Stipe, IBM Almaden Research Center
D. Rugar, IBM Almaden Research Center
H.J. Mamin, IBM Almaden Research Center
C.S. Yannoni, IBM Almaden Research Center
T.D. Stowe, Stanford University
T.W. Kenny, Stanford University
Correspondent: Click to Email
Long spin relaxation times will be important to the success of many proposed solid-state quantum computing devices, spintronic devices, and to the detection of single spins by magnetic resonance force microscopy (MRFM). However, spin relaxation may be strongly influenced by thermal magnetic fluctuations in nearby materials such as conductors and ferromagnets. We have employed MRFM with 100 spin sensitivity and 20 nm spatial resolution to study the behavior of E' centers in SiO@sub 2@ near a micron-size ferromagnetic PrFeB particle tip. Magnetic resonance was induced within a 1 nm thick selective slice at 6 GHz and 3 Kelvin in a field gradient of 1 Gauss/nm. For detection, spins were manipulated by adiabatic inversion to produce oscillatory forces on the magnetic particle mounted on a sensitive cantilever. A typical spin ensemble consisted of 2000 spins with a net polarization of 100 µ@sub B@. T@sub 1@ was measured as a function of distance from the tip and was found to systematically decrease from 13 seconds when the spins were far from the tip to about 2 seconds within 500 nm of the tip. We interpret our results in terms of magnetic noise at the spin due to small-angle, thermal magnetic moment fluctuations in the particle. No relaxation effect due to proximity to the sample surface was found for depths greater than 50 nm. This work is supported, in part, by the Office of Naval Research.