Physical Properties of Nanometer-Scale Magnets.
Abstract
As described in our original proposal, we have spent the final year of our research program investigating the physical properties of nanometer-scale magnets. This has involved several projects and associated experimental techniques. Arrays of nanometer-scale iron particles are grown by local organometallic deposition with a scanning tunneling microscope. The average magnetic properties are studied at low temperatures (5 - 100 K) with a two-dimensional hole gas Hall magnetometer. Rotation of the net array magnetization occurs by both reversible and irreversible modes, the latter revealed by Barkhausen jumps. Direct spatially-resolved measurements at room temperature with a magnetic force microscope show that the discrete jumps are due to the sudden switching of individual single-domain particles. Particles that appear structurally similar are found to be magnetically distinct. The present work employs the additive technique of local organometallic deposition with a scanning tunneling microscope (STM) to produce nanometer-scale iron particles with control of the shape and orientation. The average magnetic properties of an array of particles is compared with the properties of individual particles by complementary low temperature Hall magnetometer and room temperature magnetic force microscope (MFM) measurements, the latter producing some of the highest resolution magnetic images of submicron structures to date. Although the particles formed with the STM are seen to be structurally similar through atomic-scale topographic studies, they vary magnetically in terms of coercive fields, suggesting that anisotropy on a length scale smaller than the spatial resolution of our probes (-25 nm) is playing an important role.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 14, 1996
- Accession Number
- ADA308548
Entities
People
- David Awschalom
Organizations
- University of California, Santa Barbara