[meteorite-list] Magnetic Probe for Rocks, Recordings, Nanotechnology

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:25:41 2004
Message-ID: <200305201534.IAA03988_at_zagami.jpl.nasa.gov>

http://www.news.ucdavis.edu/search/news_detail.lasso?id=6421

Magnetic Probe for Rocks, Recordings, Nanotechnology
University Of California Davis
May 14, 2003

Editor's note: Sample images of FORC data are available. Contact Andy Fell
for details.

A technique for studying the magnetic properties of rocks developed by earth
scientists at UC Davis is drawing attention from other scientists and the
magnetic recording industry.

An international group of scientists recently met in Davis to discuss the
First Order Reversal Curve (FORC) method and its applications for studying
million-year old rocks, thousand-year old lake sediments, modern hard drives
and wholly new kinds of materials made in the lab.

Magnetic materials are made up of grains that act as tiny magnets. The size
and orientation of these grains determines the magnetic properties of the
whole material. Magnetic tapes and hard drives use those magnetic grains to
store information.

The FORC method involves subjecting materials to a series of switching
magnetic fields. How they respond gives information about the size,
orientation and behavior of magnetic grains in the material.

Rocks store magnetic information for millions of years, said UC Davis
geophysicist Ken Verosub, who with physicist Christopher Pike and geologist
Andrew Roberts (now at the University of Southampton, England) originally
developed the method.

Grains in rocks are magnetized by the Earth's magnetic field. When the
Earth's field changes, some of the grains may change orientation, Verosub
said. On a more recent timescale, changes in climate over thousands of years
leave magnetic traces in the sediment on the floor of ancient lakes and
seas.

FORC helps geologists understand how these magnetic signals are recorded in
rocks and sediments. It also provides information about magnetic
interactions between grains which could be useful for developing better hard
drives and magnetic storage devices.

Verosub and Pike have joined with physicists Kai Liu, Richard Scalettar and
Gergely Zimanyi to explore these new applications of the method. Scalettar,
Zimanyi and Pike are using simulations and computer modeling to investigate
the underlying physics behind the method.

Liu uses FORC to study novel materials, called nanomaterials because they
are made up of extremely small layers, dots or other structures, that he
makes in the lab. Such materials have novel properties compared to bulk
materials because of their extremely small dimensions.

Additional information:
FORC method Web pages

Media contact(s):
Andy Fell, UC Davis News Service, (530) 752-4533, ahfell_at_ucdavis.edu
Received on Tue 20 May 2003 11:34:01 AM PDT