1. FIRST X-RAY MICROSCOPE IMAGES WITH CLEAR ANTIFERROMAGNETIC CONTRAST
by Art Robinson
(Contact: Stohr@almaden.ibm.com)

Researchers from the IBM Almaden Research Center, the ALS, Stanford University, and Arizona State University have used the new PEEM2 photoemission electron microscope at the ALS to record the first images by any technique showing unambiguous antiferromagnetic contrast on a thin-film surface. (A highlight with images from this work is available on the ALS Web site at http://www-als.lbl.gov/als/science/sci_archive/antiferro.html.) Since antiferromagnetic films are key components in the multilayer devices in use for magnetic-disk data storage systems and are under development for future generations of computer random-access memory, the new imaging tool could have a significant commercial impact as well as contribute to our fundamental knowledge of magnetic materials.

In antiferromagnets, the magnetic moments of neighboring atoms are aligned along an axis, but there are as many moments in one direction as the other, so that the net moment is zero. Well established techniques for investigating the magnetic structure of ferromagnetic thin films and surfaces do not work with antiferromagnets, owing to the lack of a net magnetic moment. For example, x-ray magnetic circular dichroism requires a net moment for the circularly polarized x rays to interact with.

X-ray magnetic linear dichroism (XMLD) provides a way around the dilemma. Absorption of linearly polarized light depends on the square of the magnetic moment (so the opposite moments do not cancel) and depends on the angle between the antiferromagnetic axis and the polarization. Researchers elsewhere have tapped these qualities of XMLD to probe antiferromagnetic nickel oxide films. What the group working at the ALS added was the use of the PEEM2, which images, with a spatial resolution of about 50 nm, the electrons emitted from the surface of a thin film as the result of x-ray absorption. The image intensity correlates with the amount of absorption at each point on the surface.

At the ALS, the researchers studied films of nickel oxide. They made images with PEEM2 at an absorption edge (L2) of nickel that splits into two peaks with heights that depend in opposite ways on the angle between the x-ray polarization and the antiferromagnetic axis. Dividing the intensities at each point of an image made at one peak energy by the image intensities at the other peak energy gives a resultant image dominated by antiferromagnetic contrast. The image of nickel oxide obtained in this way exhibited bright lines with typical widths from 400 to 2000 nm, indicating that the average antiferromagnetic moment in the stripes was different from that in the dark background. The striped structures were correlated with surface defects observed with atomic force microscopy. With a resolution of 50 nm, however, the PEEM2 could not resolve individual antiferromagnetic domains, which were estimated to be smaller than this.

To further confirm that the image contrast was due to the antiferromagnetic structure of the sample, the researchers made measurements as the temperature of the samples approached the Neel temperature, above which antiferromagnetism disappears. In a series of images acquired at increasing temperature, the researchers found that the ratio of the multiplet peak heights in the dark areas approached the expected nonantiferromagnetic value at the Neel temperature, whereas the image contrast between stripes and background reached the expected value about 65 K below the Neel temperature. The researchers attributed the lower effective Neel temperature in the stripes to their small size (finite size effect).

Research conducted by J. Stohr and J. Luning (IBM Almaden Research Center); A. Scholl, S. Anders, and H. A. Padmore (ALS); T. J. Regan and R. L. White (Stanford University); and M. R. Scheinfein (Arizona State University).

Funding: U. S. Department of Energy, Office of Basic Energy Sciences; Stanford University Center for Materials Research; and the International Disk Drive Equipment and Materials Association.

Publication about this experiment: J. Stohr et al., Phys. Rev. Lett. 83, 1862 (1999).

2. LAST CALL FOR PHYSICAL SCIENCES INDEPENDENT INVESTIGATOR PROPOSALS, DUE DECEMBER 1
(Contact: GFKrebs@lbl.gov)

December 1, 1999, is the deadline for independent investigator (II) proposals in the physical sciences for the next running period, which will last from June to November 2000. The Independent Investigator Proposal and Request for Beamtime form can be obtained from the User Services Office or on the Web at http://www-als.lbl.gov/als/quickguide/independinvest.html. Investigators who would like to keep a previous proposal active must fill in a one-page Experiment Report and Request for Beamtime and submit it to the User Services Office by the December 1 deadline. This form is available from the User Services Office or on line at http://www-als.lbl.gov/als/quickguide/independinvest.html. (The information above does not apply to protein crystallography proposals, which have a separate process and schedule.) All II proposals have the option to remain active for two years (i.e., four six-month cycles) with the submission of an Experiment Report and Request for Beamtime every six months.

The numeric rating for each II proposal will be communicated to the investigator along with comments from the Proposal Study Panel. The cutoff rating for each beamline in the previous proposal cycle is published on the Web at http://www-als.lbl.gov/als/quickguide/pspscores.html.

Information on the proposal process and a summary of the proposal deadlines for both physical sciences and protein crystallography are available at http://www-als.lbl.gov/als/quickguide/independinvest.html. Data sheets describing the capabilities of the beamlines at the ALS are also on the Web at http://www-als.lbl.gov/als/als_users_bl/datasheets.html.

To request a proposal form by mail, contact
Ruth Pepe, ALS User Services Administrator
Tel: (510) 486-5268
Fax: (510) 486-4773
Email: alsuser@lbl.gov

3. ALS DIRECTOR REPORTS ON BUDGET, GOALS AT TOWN MEETING
by Annette Greiner

Director Daniel Chemla presented an update on the state of the ALS at a November 10 town meeting. The energetic veteran of fourteen reviews since becoming ALS Director began by reflecting on the fact that he had given presentations to key decision makers more than once a month for the past year. He is now preparing the ALS for a review by the Basic Energy Sciences Advisory Committee to be conducted early in the new year.

Chemla outlined two major goals for the ALS: to be the world leader in the VUV/soft x-ray regime and to be a world-class facility for intermediate x rays. He suggested that one way to raise the profile of the ALS is to answer the call for opportunities in the burgeoning field of complex systems, which embraces many research areas for which the ALS is already a leading facility. He also detailed a planning process that he hopes will guide the ALS through the next five years of its development. Key components of the process include biannual strategic planning retreats, regular meetings of the Science Policy Board (SPB) and the Scientific Advisory Committee (SAC), and working groups for specific initiatives.

The director outlined the ALS's current areas of scientific excellence, which include many-body processes, chemistry and catalysis, dynamics, biosciences, and analytical sciences and metrology. He pointed out that the further development of the facility will require keeping a balance between complementary areas, such as fundamental and applied science, physical and biological research, traditional and exploratory applications, VUV/soft x-ray and other spectral ranges, different experimental techniques, and development of core and noncore capabilities. Chemla outlined a five-year roadmap for accomplishing the facility's goals and maintaining these key balances. Many elements of the road map have been reviewed in detail by the SAC, and it will be presented to the SPB at its December 14 meeting.

An additional concern for the ALS is finding a way to continue its forward momentum in the face of a tight budget for fiscal year 2000. Chemla noted that this year's budget, adjusted for inflation, is almost equal to the budget for 1993, when the ALS had no users. Since roughly 70% of the ALS budget is spent on behalf of users, this will be a challenge. One strategy he introduced in order to meet this challenge is establishing self-sustaining Participating Research Teams (PRTs). These would be PRTs that are able to bring their own resources to the ALS.

Ben Feinberg, Division Deputy for Operations, spoke briefly next. He reported that the ALS has continued to deliver better than 95% of the beamtime scheduled for users while increasing the number of scheduled user hours. This performance is particularly impressive in light of the fact that operations personnel have kept the machine running well with fewer hours for scheduled maintenance. Feinberg also mentioned that the ALS has done well in the past year with respect to health and safety milestones. There were three minor injuries and no reportable incidents in fiscal 1999. A few changes have taken place among safety-related staff. We have a new radiation technician, Ray Statam; a new electrical safety officer, Tom Caronna; and a new building manager for the ALS building, Joe Harkins.

4. POSTDOCTORAL OPPORTUNITIES
(Contact: lindle@nevada.edu)

Two full-time postdoctoral positions in synchrotron radiation research, focusing on gas-phase and materials studies at the ALS, are available through the University of Nevada, Las Vegas. For more information, please see the posting at http://www.nscee.edu/XAMS/job.html.

5. UEC CORNER: NOTES FROM THE USERS' EXECUTIVE COMMITTEE
by Stephen Kevan
(Contact: kevan@oregon.uoregon.edu)

We have several pieces of information to pass along in this issue of ALS News:

We are delighted to report that a Basic Energy Sciences Advisory Committee review of the ALS has been scheduled for the first week of February. Yves Petroff has accepted the task of chairing the review committee. Petroff is the current Director of ESRF and was previously a long-time Director of LURE. This review is a follow-up to the Birgeneau panel review from more than two years ago, which was not very favorable to the ALS and which led, among many other things, to a shake-up in ALS management. The UEC will be heavily involved in planning and helping to execute this review, and we seek your advice and participation as well. At present, the ALS is making recommendations of people to serve on the committee, and input from the UEC has been requested on this matter. We will also be helping to plan the review itself in the next month. Given the current strength of the scientific program, we think that the ALS stands to regain much of the luster lost after the Birgeneau panel review and look forward to the opportunity to help make this happen.

The next meeting of the ALS Science Policy Board has been set for December 14, 1999. This panel is advisory to LBNL Director Shank and provides broad input on where the ALS should be investing its resources and how the facility should be managed. Representatives of the UEC will meet with the SPB, and we welcome any input you might like to provide.

There is currently quite a bit of discussion about much-needed space for user offices and laboratories. Jim Krupnick, Division Deputy for Planning, is working very hard on two separate projects in this area. The first project is completion of the ALS mezzanine, the enclosed space directly over the experimental floor. A very brief history of this space might be useful. The mezzanine was not actually in the scope of the original ALS construction project. With the support of the UEC at that time, several million dollars of the "trust fund" that was to have been used to build beamlines was diverted to allow construction of the mezzanine floor. There was not enough money to finish the interior of the mezzanine, so the space was not used for several years. Over the past few years, resources have been located so that about a third of it has been finished and is being used by the User Services Office, the chemical dynamics group, and the structural biology group.

LBNL funds have now been located to complete the rest of the mezzanine. Last year, with input from the UEC, the ALS devised a floor plan for completion of the mezzanine. The UEC is now advising the ALS on policies for allocation of this space. Even though there is quite a bit of space on the mezzanine, there will never be enough to satisfy all the demand, and priorities will therefore need to be set. You can well imagine the parties who have reasonable claim to office space located so conveniently near the ALS floor: beamline scientists, postdocs from LBNL and elsewhere, sabbatical visitors in residence for short and long terms, and several others. There is discussion as to whether the ALS management offices should be moved from Building 80 to the mezzanine. This would require a sizeable chunk of space but would locate the Director's office in a convenient spot for sleep-deprived users. At the risk of being deluged with opinions on the always controversial subject of space, I ask that you provide your thoughts on this subject to the UEC member nearest you.

The other potential project aimed at serving the space needs of ALS users is a proposed new building located in very close proximity to Building 6, possibly replacing the Building 7 eyesore or some other building slightly further up the hill. This project is in the conceptual design stage at present; the pile-drivers will not appear for at least a year or two. The UEC is actively involved in this planning project, and we seek your input now, as the most basic decisions are being made. I note that this project is not funded at present. To procure funds, a very strong case will need to be made with the DOE program managers that this building is something the user community seriously needs.

6. WHO'S IN TOWN: A SAMPLING OF ALS USERS

To highlight the richness of our user community and help introduce recent arrivals, we offer this listing of some of the experimenters who will be collecting data during the next two weeks at the ALS.

Beamline 1.4.3: Sherry Zhang and Phil Ross (Berkeley Lab) will continue investigating battery anode buildups. Ron Simms and Karl Neiman (Utah State Univ.) and Hoi-Ying Holman (Berkeley Lab) will be studying soil chemistry. Jessica Preciado, Ralph Greif, Boris Rubinsky, and David Otten (Univ. of California, Berkeley) will be investigating the thermal properties of polar bear hairs using the IR microscope. Felicia Hendrickson and Bob Glaeser (Berkeley Lab) will continue their studies of the photocycling of bacteriorhodopsin microcrystals.

Beamline 7.0.1: Jeff Kortright (Berkeley Lab) will conduct spectromicroscopy of magnetic films, and Prof. Roy Willis (Pennsylvania State Univ.) will study valence band photoemission of magnetic alloys.

Beamline 9.0.2: Dr. Branko Ruscic (Argonne National Lab) will be studying the photoionization of radicals.

Beamline 7.3.1.1: Zi Qiang Qiu (Univ. of California, Berkeley) will study magnetic multilayer structures using PEEM2. Harald Ade (North Carolina State Univ.) will investigate polymer blends and bilayers using PEEM2.

7. OPERATIONS UPDATE
(Contact: RMMiller@lbl.gov)

Beam reliability for the last two weeks (November 8 to 21) was 95% for user shifts. There were no significant outages.

Long-term and weekly operations schedules are available on the Web (http://www-als.lbl.gov/als/accelinfo.html). Requests for special operations use of the "scrubbing" shift should be sent to Bob Miller (RMMiller@lbl.gov, x4738) by 1:00 p.m. Friday. The Accelerator Status Hotline at (510) 486-6766 (ext. 6766 from Lab phones) features a recorded message giving up-to-date information on the operational status of the accelerator.