Microscopic
mechanisms
of magnetism
by Bruce Balfour
In the ongoing quest for faster and more
efficient magnetic data storage, designs for devices such
as read heads in computer hard drives are mostly produced
through a trial-and-error process, combining thin magnetic
films with different properties. To speed up this search,
researchers are striving for a better understanding of the
microscopic structure and interactions between ferromagnet
and antiferromagnet layers. Researchers from the ALS, Stanford
University, and Italy have now solved a piece of this puzzle
using an x-ray magnetometer at the ALS. They proved that antiferromagnets
in contact with ferromagnets form an exchange spring system.
An exchange spring combines the maneuverability of magnetically
soft materials with the permanence of magnetically hard materials.
Full
story.
Publication about this research: A. Scholl,
M. Liberati, E. Arenholz, H. Ohldag, and J. Stöhr, "Creation
of an antiferromagnetic exchange spring," Phys. Rev.
Lett. 92, 247201 (2004).
Contact: Andreas Scholl, A_Scholl@lbl.gov
Stripe domains
in coupled
magnetic sandwiches
by Lori Tamura
Ultrathin magnetic films a few atoms
thick occupy a scientific "sweet spot" at the intersection
of theory and application. Potentially lucrative as a medium
for high-density data storage, such films are also of fundamental
interest because of their low dimensionality, enabling scientists
to study systems that model two-dimensional magnetic behavior.
Nanostructures of several ultrathin magnetic layers can be
engineered to explore many interesting phenomena, including
the formation of elongated (stripe) magnetization domains.
With the ALS's photoemission electron microscope, PEEM-2,
researchers from ALS, UC Berkeley, and China looked at stripe
domains in magnetic sandwiches of cobalt, copper, and iron/nickel.
The results revealed a hidden universal dependence of stripe
domain width on variables such as film thickness and external
magnetic field. Full
story.
Publication about this research: Y.Z.
Wu, C. Won, A. Scholl, A. Doran, H.W. Zhao, X.F. Jin, and
Z.Q. Qiu, "Magnetic stripe domains in coupled magnetic
sandwiches," Phys. Rev. Lett. 93,
117205 (2004).
Contact: Z.Q. Qiu, qiu@socrates.berkeley.edu
Electrical safety
reminder
All ALS users are reminded that they
are expressly NOT permitted to work on any
energized system with:
- 0-50 volts, if the product of voltage times available
current is greater than 500 watts,
- >50 volts, if the available current is greater than 5
milliamperes,
- stored energy above 5 Joules.
Work on equipment with voltages and currents
in the above ranges are defined as "work on energized electrical
equipment" and can only be performed under very controlled
conditions. Users requiring work on electrical equipment that
falls into these categories, should contact the Electronic
Maintenance Shop at ext. 5457. The staff is available to assist
users 24 hours a day.
Contact: Georgeanna Perdue, gmperdue@lbl.gov
Reminder: General
user proposals
due January 5
 The
User Services Office is still accepting general user proposals
from scientists who wish to conduct research in the general
sciences at the ALS during the running period from July through
December 2005. The deadline for submissions is Wednesday,
January 5, 2005. (This deadline does not apply to protein
crystallography proposals, which have a separate process and
schedule.) Scientists wishing to renew a previous proposal
must download the short "ALS
Experiment Report and Request for Beamtime" form
and email it as an attachment to alsproposals@lbl.gov
by the January 5 deadline. Proposals cannot be renewed for
more than three six-month cycles after they are first submitted.
If your proposal is designated ALS-01062 or lower, then you
must submit a new proposal to be eligible for beamtime. The
following resources are available for further information:
ALS
User Services Administrator
General
user proposal process
ALS online forms
Beamline
information
Proposal
Study Panel (PSP) scores
Contact: alsproposals@lbl.gov
In memoriam:
Dale Sayers
 Our
dear colleague Prof. Dale Edward Sayers (North Carolina State
Univ.) died unexpectedly on November 25, 2004. Dale earned
his Bachelor's degree from the Univ. of California, Berkeley,
and completed his Master's and Ph.D. at the Univ. of Washington.
His Ph.D. research centered on the development of a new analytical
technique, extended x-ray absorption fine structure, or EXAFS.
His first EXAFS paper—written with colleagues Ed Stern
and Ferrell Lytle—opened a new field of research that
held its twelfth bi-annual meeting in Sweden in 2003. Professor
Sayers joined the North Carolina State University physics
department faculty in 1976. His main research interest was
in applying the EXAFS technique to the study of many systems
including amorphous alloys, the semiconductor-metal interface,
catalysts, electrochemical systems, environmentally contaminated
systems and metalloproteins. Recently, he had been affiliated
with a team that discovered and is applying a new x-ray technique
called diffraction-enhanced imaging to develop a clinical
tool for mammography, osteoarthritis investigations, and bone-density
studies. Dale garnered a number of national and international
awards, including the Bertram Warren Award (of the American
Crystallographic Association), the Centennial Scholar Award
(of Case-Western Reserve University), and the Outstanding
Achievement Award (of the International XAFS Society). Professor
Sayers was also a Fellow of the American Physical Society
and held positions as Visiting Professor/Scientist at several
international institutions. In addition, Dale served on the
ALS General Sciences Proposal Study Panel for more than five
years. Throughout his professional life, Dale's intellect
and curiosity benefited a host of scientific colleagues. His
personal integrity, humor, and comfortable communication style
permeated his life from teaching 18-year-olds to heading world-renowned
research teams. He will be dearly missed by his family and
his colleagues and friends around the world.
ALS awards and
honors
The ALS is pleased to acknowledge and
congratulate those in its orbit whose achievements have been
recognized by their election as Fellows of the American Physical
Society (APS):
- Zahid Hussain for
major scientific contributions in the physics of materials
using synchrotron radiation spectroscopies, and for enabling
discoveries by others through the development of cutting-edge
instrumentation.
- Rainer Dressler for
innovative developments in the study of electron, ion, and
photon interactions with molecules and applications to space
vehicles.
- Lou Terminello for
innovative use of synchrotron radiation spectroscopy in
revealing the electronic and atomic structure of new materials.
The APS Fellowship Program was created
to recognize members who have made advances in knowledge through
original research and publication or made significant and
innovative contributions in the application of physics to
science and technology. Each year, no more than one-half of
one percent of the membership are recognized by their peers
for election to the status of Fellow. For more information
about the APS and the Fellowship Program, visit the APS
Web site.
UEC election
results
The ALS Users' Executive Committee (UEC)
welcomes the following four new members next year: Jinghua
Guo (Berkeley Lab), Simon Morton (Berkeley Lab), Tony van
Buuren (LLNL), and student member Amanda Hudson (UNLV). The
newly elected members will take office for a three-year term
beginning January 1, 2005. UEC vice-chair Greg Denbeaux (SUNY-Albany)
will take over as chair for Dennis Lindle (UNLV), who will
serve as an ex-officio UEC member in 2005. Biographical information
about the new UEC members is available on the UEC
Election Web site. Rotating off the committee at the end
of 2004 with thanks for their service are John Bozek (Berkeley
Lab), Alexander Moewes (Univ. of Saskatchewan, Canada), Yasuji
Muramatsu (Japan Atomic Research Institute), Eli Rotenberg
(Berkeley Lab), and Sophie Canton (student member).
Contact: Greg Denbeaux, gdenbeaux@uamail.albany.edu
Latest Activity
Report now posted
 A
PDF version of the 2003
ALS Activity Report has been posted online. The Activity
Report is published annually and illustrates the depth and
breadth of the ALS scientific program with a selection of
research results. The 2003 edition contains a science feature
article on nanomagnetism research at the ALS and a retrospective
on our tenth anniversary. The report also summarizes operations,
ongoing R&D, educational outreach efforts, and special
events. Printed copies are being mailed to all users in the
ALS database within the next couple of weeks. Others can request
a copy by sending email to alsuser@lbl.gov. Be sure to include
your name, complete mailing address, and the name of the publication
being requested.
Contact: Lori Tamura, LSTamura@lbl.gov
Holiday closure
schedule
Berkeley Lab will close on the evening
of December 23 and reopen on the morning of January 3. During
the closure, the Lab will shut down as much heating and ventilating
equipment as possible to reduce costs. (The ALS experiment
floor will remain at normal temperature to prevent damage
to sensitive equipment.) The first user run of 2004 will be
January 5 - 10. The next issue of ALSNews will be published
on January 26. Have a safe and happy holiday season, and we'll
see you next year! |
