Spatial characterization of the magnetic field profile of a probe tip used in magnetic resonance force microscopy

We have developed the experimental approach to characterize spatial distribution of the magnetic field produced by cantilever tips used in magnetic resonance force microscopy (MRFM). We performed MRFM measurements on a well characterized diphenyl-picrylhydrazyl (DPPH) film and mapped the 3D field profile produced by a Nd2Fe14B probe tip. Using our technique field profiles of arbitrarily shaped probe magnets can be imaged.Comment: 10 pages, 5 figure

Localized ferromagnetic resonance force microscopy in permalloy-cobalt films

We report Ferromagnetic Resonance Force Microscopy (FMRFM) experiments on a justaposed continuous films of permalloy and cobalt. Our studies demonstrate the capability of FMRFM to perform local spectroscopy of different ferromagnetic materials. Theoretical analysis of the uniform resonance mode near the edge of the film agrees quantitatively with experimental data. Our experiments demonstrate the micron scale lateral resolution in determining local magnetic properties in continuous ferromagnetic samples.Comment: 7 pages, 3 figure

Ferromagnetic resonance force microscopy on a thin permalloy film

Ferromagnetic Resonance Force Microscopy (FMRFM) offers a means of performing local ferromagnetic resonance. We have studied the evolution of the FMRFM force spectra in a continuous 50 nm thick permalloy film as a function of probe-film distance and performed numerical simulations of the intensity of the FMRFM probe-film interaction force, accounting for the presence of the localized strongly nonuniform magnetic field of the FMRFM probe magnet. Excellent agreement between the experimental data and the simulation results provides insight into the mechanism of FMR mode excitation in an FMRFM experiment.Comment: 9 pages, 2 figure

Observation of Pure Spin Transport in a Diamond Spin Wire

Spin transport electronics - spintronics - focuses on utilizing electron spin as a state variable for quantum and classical information processing and storage. Some insulating materials, such as diamond, offer defect centers whose associated spins are well-isolated from their environment giving them long coherence times; however, spin interactions are important for transport, entanglement, and read-out. Here, we report direct measurement of pure spin transport - free of any charge motion - within a nanoscale quasi 1D 'spin wire', and find a spin diffusion length ~ 700 nm. We exploit the statistical fluctuations of a small number of spins ($\sqrt{N}$ < 100 net spins) which are in thermal equilibrium and have no imposed polarization gradient. The spin transport proceeds by means of magnetic dipole interactions that induce flip-flop transitions, a mechanism that can enable highly efficient, even reversible, pure spin currents. To further study the dynamics within the spin wire, we implement a magnetic resonance protocol that improves spatial resolution and provides nanoscale spectroscopic information which confirms the observed spin transport. This spectroscopic tool opens a potential route for spatially encoding spin information in long-lived nuclear spin states. Our measurements probe intrinsic spin dynamics at the nanometre scale, providing detailed insight needed for practical devices which seek to control spin.Comment: 7 pages, 2 figures, under consideration at Nature Nanotechnolog

Manipulating Spins by Cantilever Synchronized Frequency Modulation: A Variable Resolution Magnetic Resonance Force Microscope

We report a new spin manipulation protocol for periodically reversing the sample magnetization for Magnetic Resonance Force Microscopy. The protocol modulates the microwave excitation frequency synchronously with the position of the oscillating detection cantilever, thus allowing manipulation of the spin magnetization independent of both magnetic field gradient strength and cantilever response time. This allows continuous variation of the detected sample volume and is effective regardless of spin relaxation rate. This enhanced flexibility improves the utility of MRFM as a generally applicable imaging and characterization tool.Comment: 3 pages, 3 figure