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