Magnetics Society Distinguished Lecturers for 2008

Contact individual Distinguished Lecturer at the email addresses indicated. Each Distinguished Lecturer makes his/her own schedule, so contact them early before their schedules are filled. For additional assistance and/or further information contact the Distinguished Lecturer Coordinator (Roy Chantrell, rc502@york.ac.uk).

Patterned Nanomagnetic Bits and Devices

Bruce D. Terris
Hitachi Global Storage Technologies

As conventional magnetic recording technology extends to ever higher areal density, it is possible the often predicted, and constantly increasing, density limit will be reached. This limit will likely be in the range of 750 – 1000 Gb/in2. The use of nanofabrication to create patterned magnetic elements, or patterned media, is one of the proposed approaches with the promise of delaying the onset of superparamagnetism and thus enabling higher areal density. I will discuss many of the challenges that must be overcome for patterned media to be successful, including fundamental physics and material science issues, new fabrication technologies, nm-scale manufacturing tolerances, and low cost budgets.

One of these challenges is to controllably reverse one magnetic element, or bit, without affecting the neighboring elements. A narrow anisotropy distribution will be required, yet data suggest that as the element size shrinks, the distribution widens. This distribution arises from a number of sources, including shape and size distributions, edge effects, variations in the full film anisotropy and magnetostatic fields from neighboring elements. As will be discussed, understanding and controlling the switching properties of magnetic nanostructures is critical not only for patterned media, but for device applications such as MRAM cells and spintronic devices and, for current induced as well as field induced reversal.

Bruce D. Terris received the B.S. degree in applied physics from Columbia University and the M.S. and Ph. D. degrees in physics from the University of Illinois at Urbana-Champaign. After receiving his doctorate, he was a post-doctoral fellow for two years at Argonne National Laboratory. In 1985, he joined IBM as a Research Staff Member at the Almaden Research Center, San Jose, CA, and subsequently joined Hitachi GST when it was founded in 2003 and where he is currently the manager of Nanostructures group. His research interests have included thin film superconductivity and magnetism, contact electrification of insulators, and new types of scanning probe microscopes (STM, AFM, near-field optical, etc.). His current research is on nanoscale patterning of magnetic structures, thermally assisted magnetic recording, novel approaches to high density data storage and spin torque devices. He has co-authored over 90 refereed publications and been issued more than 20 US patents. He has recently served as program co-chair for Intermag 2006 and program chair for the Nanoscale Science and Technology Division of AVS for 2005. He currently serves on the Administrative Committees of the IEEE Magnetic Society and the MMM conference and will serve as US program chair for Intermag 2008 and US Conference Chair for Intermag 2011 (Taipei). He is a Fellow of the APS and AVS, and is a member of IEEE.

Contact: Dr. Bruce D. Terris, Hitachi Global Storage Technologies, San Jose Research Center, 3403 Yerba Buena Road, San Jose, CA 95135, USA; telephone +1 408 717 5262; Fax:+1 408 717 9065; e-mail: Bruce.Terris@ieee.org

Turbulent Transitions and Frustrated States: Some Issues in Reversal

Dr. R Stamps
University of Western Australia

A trend over the last few decades in many areas of science and technology has been to modify and control material properties through careful choice of dimensions. A key feature of such endeavors is to create useful physical properties governed by surfaces and interfaces. Important length scales in magnetic metals are spin diffusion, which ranges from angstroms to nanometers, and exchange lengths, which can be on the order of several nanometers. Advanced techniques now allow us to create structures on these length scales in three dimensions. This is a remarkable achievement because it often represents true atomic level engineering, and is based on years of detailed study of thin films and multi-layers.

A rich wealth of fascinating phenomena has emerged from studies of these types of constrained geometry structures within the contexts of high speed magnetization reversal and magnetic domain stability. This lecture will provide an introduction to essential concepts, illustrate examples of new physics, and present some challenging, unanswered questions. Topics will include examples of frustration in exchange bias systems and analogies to spin glasses; control of nonlinear processes in patterned magnetic structures and parametric processes incurred during high speed reversal; pinned and viscous domain wall motion in ultra-thin films and nanowires; and electronic and spin wave transport through domain walls. These examples will illustrate reversal processes and domain stability issues relevant for a wide variety of magnetic device applications, including concepts being explored for novel spin logic schemes.

Robert Stamps received BS and MS degrees from the University of Colorado, and a PhD in Physics from Colorado State University. He has taught at the University of Colorado, Ohio State University, and has been with the University of Western Australia since 1997 where he is now Associate Professor in Physics. Dr Stamps has held a Humbolt Junior Fellowship at RWTH Aachen, CNRS Professorial Fellowships (Strasbourg and Orsay), CNR Fellowship (Florence), a University of Paris VII Visiting Professorship, and received a Faculty Excellence in Teaching award in 2001. His work on exchange bias and magnetization dynamics featured in his tenure as the 2004 Wohlfarth Lecturer. Professor Stamps has published over 140 papers on a range of topics in magnetism, including linear and nonlinear dynamics of magnetic and ferroelectric nanostructures, frustrated spin systems and spin glasses, inelastic light scattering and ferromagnetic resonance, spin electronics and domain wall dynamics in constrained geometries and random systems. He is a member of the IOP, Australian AIP, and IEEE Magnetics Society, chair of the 2007 MML Symposium, and currently serves on the advisory editorial board of the Journal of Magnetism and Magnetic Materials.

Contact: Robert Stamps, School of Physics M013, University of Western Australia, 35 Stirling Highway, Crawley WA 6018; Telephone: (+61) 8 6488 3794, Fax: (+61) 8 6488 1014, e-mail:stamps@physics.uwa.edu.au, web page: http://www.physics.uwa.edu.au/about/research/condensed

The Spin on Electronics!

Stuart Parkin
IBM Almaden Research Center

Today, nearly all microelectronic devices are based on storing or flowing the electron’s charge. The electron also possesses a quantum mechanical property termed “spin”, that gives rise to magnetism. Electrical current is comprised of “spin-up” and “spin-down” electrons, which behave as largely independent spin currents. The flow of these spin currents can be controlled in thin-film structures composed of atomically thin layers of conducting magnetic materials separated by non-magnetic conducting or insulating layers. The resistance of such devices, so-called spin-valves and magnetic tunneling junctions, respectively, can be varied by controlling the relative magnetic orientation of the magnetic layers, giving rise to magnetoresistance tailored for different applications. Recent advances in generating, manipulating and detecting spin-polarized electrons and electrical current make possible new classes of spin based sensor, memory and logic devices, generally referred to as the field of spintronics. In particular, the spin-valve is a key component of all magnetic hard-disk drives manufactured today and enabled their nearly 1,000-fold increase in capacity over the past eight years1. The magnetic tunnel junction allows for a novel, high performance random access solid state memory which maintains its memory in the absence of electrical power. The respective strengths of these two major classes of digital data storage devices, namely the very low cost of disk drives and the high performance and reliability of solid state memories, may be combined in the future into a single spintronic memory-storage technology, the magnetic Racetrack. The Racetrack is a novel three dimensional technology which uses nanosecond long pulses of spin polarized current to move a series of magnetic domain walls along magnetic nanowires2.
1. Stuart Parkin et al., Magnetically engineered spintronic sensors and memory. Proc. IEEE 91, 661-680 (2003).
2. S. S. P. Parkin, US Patent # 6,834,005, 6,898,132, 6,920,062, 7,031,178, and 7,236,386 (2004-2007).


Stuart Parkin is an IBM Fellow and Manager of the Magnetoelectronics group at the IBM Almaden Research Center, San Jose, California and a consulting professor in the Department of Applied Physics at Stanford University. He is also director of the IBM–Stanford Spintronic Science and Applications Center, which was formed in 2004. He received his BA and PhD degrees from the University of Cambridge and joined IBM as a postdoctoral fellow in 1982, becoming a permanent member of the staff the following year. In 1999 he was named an IBM Fellow, IBM’s highest technical honor. Parkin’s research interests have included organic superconductors, high-temperature superconductors, and, for almost the past two decades, magnetic thin film structures and spintronic materials and devices for advanced sensor, memory, and logic application. He is a Fellow of the Royal Society, the American Physical Society, the Institute of Physics (London), the Institute of Electrical and Electronics Engineers, and the American Association for the Advancement of Science. Parkin is the recipient of numerous honors, including a Humboldt Research Award (2004), the 1999-2000 American Institute of Physics Prize for Industrial Applications of Physics, the European Physical Society’s Hewlett- Packard Europhysics Prize (1997), the American Physical Society’s International New Materials Prize (1994), the MRS Outstanding Young Investigator Award (1991) and the Charles Vernon Boys Prize from the Institute of Physics, London (1991). In 2001, he was named R&D Magazine’s first Innovator of the Year and in October 2007 was awarded the Economist Magazine’s “No Boundaries” 2007 Award for Innovation. In 2007 Parkin was named a Distinguished Visiting Professor at the National University of Singapore, a Visiting Chair Professor at the National Taiwan University, and an Honorary Visiting Professor at University College London, The United Kingdom. Parkin has been awarded Honorary Doctorates by the University of Aachen, Germany and the Eindhoven University of Technology, The Netherlands. Parkin has authored ~350 papers and has ~63 issued patents.

Contact: Parkin can be reached at IBM Almaden Research Center, 650 Harry Road, San Jose, CA 95120-6099, USA; tel. 408-927-2390 and e-mail: parkin@almaden.ibm.com.

Spintronic biochips for biomolecular recognition

P.P.Freitas
INESC MN, Lisbon, Portugal and Physics Department, Instituto Superior Tecnico, Lisbon, Portugal

Integrated spintronic biochip platforms are being developed for portable, point-of-care diagnostic applications. The platforms consist of a microfluidic unit where the bioassay takes place, an arraying and detector chip consisting of target arraying current lines and integrated magnetoresistive sensors, and electronic control and readout boards. Probe biomolecules are immobilized by microspotting over sensor sites, and target biomolecules, labeled with magnetic nanoparticles are arrayed over the probe sites ( magnetically assisted hybridization). After proper washing, hybridized targets are recognized by the fringe fields created by the magnetic beads, detected by the incorporated magnetoresistive sensors. Detecting geometries will be reviewed, using either out-of-plane or in-plane bead excitation, and dc or ac detection/excitation. Detection limits using spin valve and tunnel junction sensors will be presented, depending ultimately on platform electronic noise, and sensor noise characteristics. Applications to gene expression chips ( Cystic Fibrosis gene mutation detection) and imuno assay chips ( anti-body-antigen recognition, e-Coli, Salmonella detection) will be presented. Spintronic biochip are also being integrated into multi -module lab-on-chip platforms including i) biomolecule extraction from biological fluids ( magnetophoresis ), ii) PCR modules ( if required), and iii) the biomolecular recognition module. Alternative spintronic biochip geometries will also be presented ( lateral flow biosensors), where a magnetoresistive reader scans the surface of a porous strip, where labeled target biomolecules bind to immobilized probes. Finally, a brief review of other biomedical applications of magnetoresistive sensors will be given, from hybrid sensors targeted at biomedical imaging, to magnetic tweezers/sensors for DNA translocation monitoring.

Contact email address: pfreitas@inesc-mn.pt

Paulo Freitas is a Full Professor of Physics at the Instituto Superior Tecnico (IST) in Lisbon, and the Director of INESC Microsystems and Nanotechnologies. Current research topics include MRAMS, read heads for ultra high density recording, magnetoresistive biochips, and sensors for biomedical applications. He has been involved in research in the area of magnetoresistive materials and devices since he received his Ph.D in Solid State Physics from Carnegie Mellon University in 1986. His PhD thesis was on the subject of anisotropic magnetoresistance of ferromagnetic thin films and alloys. He then joined IBM Research at Yorktown Heights as a post doctoral fellow working on high-TC superconductivity and transport properties of ferromagnetic thin films. In 1988 he joined INESC in Lisbon, where he started the Solid State Technology Group. In 1989 he became Professor of Physics at the Instituto Superior Tecnico in Lisbon. From 1992 to 1996, he was responsible for the start up and operation of INESC´s ASIC back-end of the line microfabrication facility. From 1996 till now, his research areas expanded to magnetoresistive read elements for magnetic data storage, magnetoresistive sensors, MRAMS, and biomedical applications including magnetoresistive biochips. He became director of INESC Microsystems and Nanotechnologies in 2001, and Full Professor of Physics at IST in 2002. Over this period, he co-authored over 200 technical papers and several chapter books. Professional activities include membership in IEEE, participation in several Publication/Program/Advisory Committees of MMM and Intermag Conferences.

Contact: Paulo Freitas, Physics Department, Instituto Superior Tecnico, Lisbon, Portugal. e-mail: pfreitas@inesc-mn.pt