They now have a new tool developed by a team from the National Institute of Standards and Technology (NIST), the University of Maryland Nanocenter and the Royal Institute of Technology in Sweden — a method to detect defects in magnetic structures as small as a tenth of a micrometer even if the region in question is buried inside a multilayer electronic device.*
Trapped beneath the magnetic tip of a microscale cantilever, spin waves can be used to non-destructively measure the properties of magnetic materials and search for nanoscale defects, especially in multilayer magnetic systems like a typical hard drive, where defects could be buried beneath the surface. Credit: McMichael/NIST
The technique demonstrated at the NIST Center for Nanoscale Technology (CNST) builds on work by researchers at the Ohio State University.** The idea is to trap and image oscillating perturbations of a magnetic field—"spin waves"—in a thin film. Trapped spin waves provide scientists with a powerful new tool to nondestructively measure the properties of magnetic materials and search for nanoscale defects that could or have caused memory failures, especially in multilayer magnetic systems like a typical hard drive, where defects could be buried beneath the surface.
According to NIST researcher Robert McMichael, when left alone, the material's magnetization is like the surface of a pond on a windless day. The pond is comprised of smaller magnetic moments that come with the quantum mechanical "spin" of electrons. Tap the surface of the pond with a piece of driftwood, or microwaves in this case, and the surface will begin to ripple with spin waves as the microwave energy jostles the spins, which, in turn, jostle their neighbors.
"The trick we play is to tune the microwaves to a frequency just outside the band where the spin waves can propagate—except right under our magnetic probe tip," says McMichael. "It's like the pond is frozen except for a little melted spot that we can move around to check magnetic properties at different spots in the sample."
The trapped spin waves are disturbed by defects in the material, and this effect allows the defects to be characterized on 100 nm length scales.
Previous work had shown this same effect in magnetic spins that were oriented perpendicular to the magnetic film surface, meaning that the individual spins coupled strongly with their neighbors, which limited the resolution. This new work adds the extra feature that the magnetic spins are aligned in plane with one another and are not as tightly coupled. This setup is not only more representative of how many magnetic devices would be structured, but also allows for tighter focusing and better resolution.
* H-J. Chia, F. Guo, L.M. Belova and R. D. McMichael. Nanoscale spin wave localization using ferromagnetic resonance force microscopy. Physical Review Letters. 108, 087206 (2012). http://prl.aps.org/pdf/PRL/v108/i8/e087206.
** See Lee et al. Nanoscale scanning probe ferromagnetic resonance imaging using localized modes. Nature. 466, 12. Aug. 12, 2010. doi:10.1038/nature09279.
Mark Esser | EurekAlert!
Active pits on Rosetta’s comet
03.07.2015 | Max Planck Institute for Solar System Research, Göttingen
Researchers find the macroscopic Brownian motion phenomena of self-powered liquid metal motors
02.07.2015 | Science China Press
Wind turbines could be installed under some of the biggest bridges on the road network to produce electricity. So it is confirmed by calculations carried out by a European researchers team, that have taken a viaduct in the Canary Islands as a reference. This concept could be applied in heavily built-up territories or natural areas with new constructions limitations.
The Juncal Viaduct, in Gran Canaria, has served as a reference for Spanish and British researchers to verify that the wind blowing between the pillars on this...
New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions
A new technique pioneered at the U.S. Department of Energy's Brookhaven National Laboratory reveals atomic-scale changes during catalytic reactions in real...
Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and a half billion years ago.
Think of an object made of iron: An I-beam, a car frame, a nail. Now imagine that half of the iron in that object owes its existence to bacteria living two and...
A team of scientists including PhD student Friedrich Schuler from the Laboratory of MEMS Applications at the Department of Microsystems Engineering (IMTEK) of...
The three-year clinical trial results of the retinal implant popularly known as the "bionic eye," have proven the long-term efficacy, safety and reliability of...
25.06.2015 | Event News
16.06.2015 | Event News
11.06.2015 | Event News
03.07.2015 | Press release
03.07.2015 | Agricultural and Forestry Science
03.07.2015 | Health and Medicine