TMRC 2005 REVIEW
The 16th Annual Magnetic Recording Conference (TMRC 2005) was held at the Stanford University, California, from Aug. 15 to 17. The main topics for the conference were Heads and Systems. This included Read Head, Write Head, Perpendicular recording heads and systems, Recording systems, Advanced coding/detection and Reliability/Mechanics.
The conference was a huge success with 406 registrants, the largest attendance in the history of this conference. On Tuesday evening, Mark Kryder, CTO ofSeagate Technologies, discussed future technology options for the magnetic recording industry. In his view, conventional Perpendicular magnetic recording is limited to about 0.5 Tbit/sq inch areal density. Heat Assisted Magnetic Recoding (HAMR) and Patterned media options are expected to be required beyond 0.5 Tbit/sq inch areal density point.
The technical sessions were well represented by both the industry and the universities. There were 36 invited talks with authors from 23 institutions: ActionFront Data Recovery Labs, Agere systems, Alps, Anelva, ChannelScience, Fujitsu, Headway, Hitachi, Hutchinson, Matsushita, Maxtor, Panasonic, SAE, Seagate, Sony, StorageTek, TDK, Toshiba, UC Berkeley, CMU/DSSC, UCSD/CMRR, Data Storage Institute Singapore and Harvard. Along with these invited papers, 16 Poster submissions were also presented in two day very popular poster sessions, which accompanied by Bierstube, were highly enjoyed by the attendees. The authors for Poster-only papers were from additional 21 institutions: Universita di Ferrara (Italy), Universita di Brescia (Italy), Akita Institute of Technology (Japan), Waseda University (Japan), Tandberg Storage (Norway), Moscow State University, Kharkov Politechnical Institute (Ukraine), Samsung, The University of Alabama, Unversity of Limerick (Ireland), Ruterges University, Univ. of Cambridge, Stanford Unversity, National Taiwan Unversity, Imago Scientific Instruments Corp., Toshiba, Unversity of Toledo (Ohio), National Unversity of Singapore, Niigata Institute of Technology (Japan), Kogakuin University (Japan). Such a diverse representation from both industry and universities from around the globe confirms the international nature and popularity of this conference.
TMRC 2005 conference clearly showed transition to the CPP sensors and the Perpendicular recording.
The papers A-1 (TDK,”A performance study of next generation’s TMR head with advanced design”) and F-1 (SAE,”Reliability of Tunneling MR recording head—Lifetime, Failure mode and Production screening”) on Tunnel MR heads demonstrated performance and reliability of these heads. One notable result from paper F-1 (SAE) is that the short-lifetime heads can be screened by using appropriate limits for %dMRR change (head resistance change between high and low current). More positive resistance change implies that the TMR barrier has a larger metallic shunt path in the barrier. These are the heads found to have shorter lifetime. Also discussed were reversible resistance change of the head due to charge trapping and then charge release causing time dependent changes in head resistance and output signal. Anelva Corp. (paper A-3,”Huge MR and low RA in magnetic tunnel junctions with crystalline MgO barrier”) showed optimization of the CoFeB/MgO/CoFeB type Tunnel MR sensor. It was shown that near zero magnetostriction and TMR near 100% is achievable using Co64Ni11Fe6B19 type free layer. Seagate (paper A-2, “Characterization and integration of TMR heads in high capacity Hard disk drives”) demonstrated use of Tunnel MR heads in disk drives and also claimed that these heads can be produced without 1/f type head noise, however, it offered no barrier composition or other design/process details required to eliminate or screen the heads with 1/f noise. There were four papers on CPP GMR heads. Alps (paper A-5,”Narrow track width CPP spin valve heads utilizing Half-Metallicity materials”) claimed superior performance, dR/R = 11 %, for the all metal dual CPP GMR heads containing reference/free layers of half-metallicity materials. Extension to smaller area sensors with this structure as compared to the Tunnel MR is the major motivation due to limitations of Tunnel MR for high data rate applications. Alps also compared performance of this CPP GMR sensor against Tunnel MR made from TiOx barrier and demonstrated that CPP GMR achieves performance similar to Tunnel MR but with much lower RA product. These CPP GMR heads with track width of 70 nm exhibited spectral SNR of 15 dB and bit error rate comparable to CIP GMR heads. A paper from Hitachi (paper B-2,”Mag-noise fluctuations in CPP GMR read heads”) on the CPP GMR demonstrated that the reference layer instability caused by the spin torque likely sets sense current limits for the all metal dual CPP GMR operating under large sense current. A paper by Fujitsu (B-6,”Ultra high magnetic moment films for write head”), showed larger saturation magnetization (near 2.57 T) for the Co30Fe70/Pd superlattice films for the write pole application.
Several speakers demonstrated areal density beyond 200 Gbit/sq inch using Perpendicular recording technology. Hitachi (Paper C-1,”Head challenges for Perpendicular recording at high areal density”) demonstrated areal density near 230 Gbit/sq inch using Perpendicular recording disk and CIP GMR read heads. Seagate (paper A-2) demonstrated areal density near 254 Gbit/sq inch using Perpendicular recording disk and Tunnel MR heads. Toshiba (paper D-1,”Perpendicular drive integration”) described Perpendicular magnetic recording drive integration.
Several other papers discussed important new technologies for the magnetic recording industry. A Poster submission from Akita Institute of Technology titled “Novel shielded single pole head with planar structure “ by Ise et al., showed novel head structure exhibiting smaller drop in head field as the shield yoke height is increased compared to conventional single pole heads. Another Poster submission from Akita Institute of Technology and Waseda University,“Controlling magnetic domain structures for the core of the Cusp-field single pole head” by Yamakawa et al., showed yoke/shield design to achieve favorable domain structure which is required for high magnetic stability and high frequency performance. A paper (F-5,”Demonstration of external shock resistance greater than 2000 G during R/W operations on a 0.85 inch HDD with balanced type head suspension”) from Matsushita/Panasonic demonstrated suspension design exhibiting greater than 2000 G external shock resistance. A paper (F-3,”Some air bearing slider designs for areal density of 1 Tbit/sq inch) from UC Berkeley showed several slider designs suitable for 1 Tb/ sq inch magnetic recording. Several invited papers on the novel coding/detection schemes were also presented.
PICTURES OF A CONFERENCE
THE MAGNETICS SOCIETY ACHIEVEMENT AWARD
Robert E. Fontana, Jr was presented with the MAGNETICS SOCIETY ACHIEVEMENT AWARD at the Magnetic Recording Conference. The Award consists of a $2500 check and certificate.
Bob Fontana upon receiving the Award:
Thank you, Denis and Bruce for this award. Let me also thank the nominating committee for their confidence in selecting me as the 2005 recipient of the IEEE Magnetics Society Achievement Award. Most important, I want to acknowledge and thank my wife, Barbara, who has provided me support and encouragement for my activities in magnetism and for my volunteer efforts for the society. Thank you so very much, Barbara, for your support!!!
I recently reflected on my magnetism career for the last 30 years when Bruce asked me for a brief biography. I chose magnetism as a career because of an event at MIT in 1970 when an IEEE Magnetics Society representative, Andy Eschenfelder, talked about a new memory technology, Magnetic Bubbles, and showed video tape pictures of bubbles or bits moving around shift registers. So, I traded in the concepts of holes and electrons and “junction physics” for spin and domain walls and here I am today.
Seriously, my career (technical and service) in magnetism has been characterized by the good fortune of having mentors and the good fortune of riding the Moore’s Law curve in a technology.
At MIT, Prof. Epstein, my advisor, taught me the meaning of “it is not finished until it is finished” and introduced me to the concept of volume effects in materials, a code word for not semiconductors and for magnetism and ferroelectrics and mass transport. Prof. Dennis Buss gave me an industrial perspective for non semiconductor devices.
At TI, Dean Toombs, a VP in charge of Bubbles, taught me the concept of the “tyranny of numbers” in device processing. He also said that in this processing business to survive, you only have to be right more than you are wrong (he showed me the transitions he managed from 1” to 2” to 3” silicon) but he said never be wrong two times in a row. Dennis Buss, now a TI VP and the inventor of the CCD concept, taught me to be aware of the capabilities of Si CMOS and scalability as I was leaving for IBM
At IBM, a few mentors come to mind: Ta Lin Hsu who decreed that one will liftoff FeMn and it will not corrode, Ching Tsang who said “thou shalt keep every free layer on a “magnetic leash”, i.e. stabilization, Chris Bajorek who said the free layer will be thinner than 300A, Heiner Sussner who said that you can process spin valves in Research, Prakash Kasiraj for asking me to assist Physical Science in building something called an MTJ. Also, thanks to Prakash Kasiraj and Bob Scranton and Rick Dill for helping me in my external technical visibility in the magnetics and engineering communities.
For the magnetics society, my comments are that one should be careful of mentors. Their goal is acquiring your time. A few experiences follow: Fred Haggedorn introduced me to conference work with a request in 1984 to be Publications Chair for Intermag. This was a three year term, and Barbara, thank you for those lost weekends when we jointly typed up, in camera ready form, the table of contents for those three conferences. To Dennis Mee, Mark Kryder, Dave Thompson, thank you for encouraging me to enter into Magnetics Society politics as President of the Society. Under my administration the society lost 30% of its phantom assets (DOT COM investments by IEEE) and spent 30% of the IEEE’s retainer lawyer fees due to MMM conference issues. The results of those fees and my administration are that today we (our Society) now have a truly global conference strategy with sound financial underpinnings.
Lastly, it has been a good run with Moore’s Law. Here is my favorite slide. My process work in my MIT Thesis used 100 um lithography features and today, 30 years later, my process work involves 50 nm processing or a factor of 2000 or 28% per year.
Thank you again, very much.
Student Travel Awardees of INTERMAG 2005 in Nagoya
Intermag Asia 2005
I would like to thank the Awards Committee, Dr. Carey, and Dr. Gurney to offer me the student travel award for attending 2005 Intermag in Nagoya, Japan. It gave me a great opportunity to share some of my research results with top researchers worldwide. The award process worked very well for me and the instructions were very clear. I obtained my reimbursement no later than two weeks after the end of the conference. The conference was well-organized. Over three thousand people attended it. I gave my presentation on Apr. 8 (Session HB, Head Disk Interface II) to a large audience. Meanwhile, I could learn the most advanced scientific and technological developments in my field. It was a special experience for me.
I particularly appreciated the timing of the conference. April is probably one of the best seasons to visit Japan. I enjoyed the beautiful cherry blossoms (the duration was only about two weeks, from Apr.1 to Apr. 15) and the magnificent EXPO 2005. Many countries around the world exhibited their fascinating cultures. Figure 1 was taken in the Central Asia Pavilion. A young lady was writing near a giant sleeping Buddha, forming an interesting contrast. Figure 2 shows the Toyota Partner Robot, which was capable of performing instruments. The technical tour to Toyota motor plants was a great
plus to the conference. For the first time I had a chance to visit Toyota’s world class manufacturing lines and to learn how efficient the process was. Once again, I would like to thank the Awards Committee for the kind offer.
Intermag 2005 for me
As one of the lucky 25 winners who received the Student Travel Award to go to Nagoya, Japan, I
Nagoya, Japan – we arrive in the late afternoon of April 3rd at the airport of this city. The building
The hotel room is small and cozy, very clean and neat, and we get a nice sleep this first night. There is
Most of my stay I spent attending the conference sessions held at the Nagoya Congress Center, a vast
Since my area of research is FePt nanoparticles, I tried to attend most presentations about this media,
From Nguyen Thi Hoang Yen
The award process was done very smoothly for me. The application procedure was simple. I had no problem at all in the whole process.
This was the first time for me to experience an INTERMAG Conference, and it was really interesting. I'm studying Spin Transfer Induced Magnetic Switching. At the conference I attended the sections regarding Spin Torques and Magnetic Tunnel Junctions, MRAMs, both poster and oral, and some others. While in the oral sections I could get useful information from many interesting presentations, in the poster section I had the chance to discuss in details with the authors about their research work which I was interested in. Actually, this was very good opportunity if one wants to learn and get to know something that never appears in publication. The evening Symposium on MRAM was also very informative to me.
Furthermore, Nagoya is a very nice, clean city. It is not crowded at all as I imagined before when I thought of Japanese cities. The Congress Center where the Conference took placed also impressed me with its architecture. This first visit of mine in Japan has left a fine image in my memory.
Finally, I would like to thank the IEEE Magnetics Society and the Committee for having supported me to attend the 2005 INTERMAG Conference, and hope, in the future, more students will have a chance as I did.
Nguyen Thi Hoang Yen
Trip to Nagoya—INTERMAG 2005
As one of the 25 selected student awards winners worldwide, I was fortunately supported by the IEEE Magnetics Society to attend the INTERMAG 2005 conference, which was held in Nagoya in April’05. Even though the conference has been closed successfully and smoothly, it still left a deep and unforgettable memory in my mind.
Time passed by so quickly, and soon it was time to come back. However, the 5-day conference impressed me very much with the wonderful talks, advanced technology, pleasant times with my friends, enjoyment of Japanese-style service, and the beautiful scenery in Nagoya. The trip to Nagoya was really an unforgettable experience for me.
***********Student Awardee Report from TMRC
By Lingyan sun
During my stay in Stanford, California for the TMRC conference from Aug. 15th-17th, 2005, I was able to listen to most of the talks and also made a presentation in the session E. My overall opinion for the conference is that it is among the highest quality within the conferences that I have attended in the magnetic recording area.
Information For future Student Travel Award Winners
The International Storage Technology Symposium (ISTS) began as the International Symposium on Barium Ferrite in 1992 and has, since then, evolved to become an event embracing all storage technologies and media. It is truly international in scope, and counts academic, research, industry and government organizations among its participants. ISTS meets every two years (although, for various reasons, the one in 2003 was not held) in early September in the southern coastal town of Kalamata in the province of Messinia on the Peloponnesus in Greece, an area rich in history and archeological sites, and which is also home, in Pylos, to some of the earliest written records. From 40 to 60 participants gather for the weeklong symposium. Sessions run from 9 am to 1 pm and again from 5 pm to 7 or 8 pm. Visits to ancient and medieval sites, museums, and theaters are part of the program and take place during the ride in the Symposium bus from Athens to Kalamata, on the way back, and on Wednesday morning. This being a Symposium, not as contrasted to a Conference, intellectual stimulation is intertwined with physical enjoyment in the form of traditional Greek dancing, music and food.
The objective of ISTS’05 was to bring together leading scientists and engineers from around the world to discuss:
The Symposium wishes to thank the governments and authorities of the city of Kalamata and the state of Messinia for the reception they organized for the participants, and also for the cultural programs in Kalamata. Symposium participants enjoyed a relaxed morning in Pylos on Wednesday the 14th September, followed by a brief stop in Methoni before riding to Finikundae for a pre-lunch dip and swim in the Mediterranean. On Friday the 16th September, the Symposium bus took participants to Olympia where, in the 7th century BC, the Olympic games started.
1. Advanced Media – organized by Dieter Weller, Seagate
In his overview, Dieter Weller pointed out out a trilemma in the dash to higher areal densities: achievable areal densities are limited by trade-offs between SNR, thermal stability and writeability. The path ahead provided a number of trilemma breakers: perpendicular recording, heat-assisted magnetic recording (HAMR), bit- patterned and self-organized magnetic structures (SOMAs). Toshiba has been the first to bring a PMR product to market and modeling suggests that densities of 400-500 Gb/in2 in four to five years. HAMR will take us at least a step beyond, and tests have shown thermal relaxation time of 100 to 500 ps. SOMA is a strategy to achieve bit-patterned media without lithographically defining the bit. Self-organizing nanostructures will eventually be needed to extend magnetic recording technology. Timing windows are more stringent with bit-patterned media. In summary, Weller stressed the need for self assembly to push AD beyond 1 Tb/in2 and need for atomistic modeling at grain sizes of 3-4 nm. PMR limit is seen near 500 Gb/in2 based on micromagnetic modeling. HAMR potential is linked to availability of small grain high Ku media. BPM: Self-Organization methods (bottom up or top down) needed at 1 Tb/in2 and beyond.
233 Gb/in2 HGST PMR demo; -2 Byte error rate at 15% OTC; -4.3 on track Byte error rate; have several head media combinations at ~ 200 ktpi x 1000 kbpi; says that getting to 233 Gb/in2 happened quickly. They used a shielded head with a gap of 50nm.
Richter: PMR can be extended by using composite media (shows phase diagram H/Hhard vs coupling); two spin model; gain factor < 2; switching field reduction strongest at small field angles;
Gustafson: INSIC roadmap talk; 40% growth; 500 Gb/in2 PMR possible; 1 Tb/in2 with titled fields and tilted media etc. but significantly delayed compared to 40% CAGR (~2013?). Points to STE as time bomb; says that thermal stability needs to include ATE and STE measurements;
Pardavi-Horvath (GWU): Preisach modeling of stability of patterned media; her model system is 40x40x3 mm3 squares of garnet; discusses domain wall switching with nucleation at defects is dominant reversal mechanism; good physics, however domain sizes are much smaller in modern BPM.
Aoi (Tohoku): formerly Hitachi Ltd – now Tohoku; still works with Hitachi and also with Twente group (NL);
2. Metrology - Kevin O’Grady, University of York
I opened this session myself, giving a presentation of magnetic characterisation of perpendicular media. Essentially this concerned the determination of time dependent characteristics of media with an SUL using a highly stable MOKE. The conclusion of this work is that activation volumes determined at the coercivity are not representative of the minimum size of a written bit since the activation volume at the nucleation field is significantly larger. Of course to write a bit of information, a region of reversal must first be nucleated and hence it is this size that limits the data density rather than that determined at the coercivity.
The second presentation in the session was by Hartmut Rohrmann from Unaxis, who described the latest technology available for the deposition of perpendicular media from his company. His presentation included a detailed description of the deposition of CoPd multilayer stacks which can be produced at very high rate using circulus technology.
The last two talks in the session were provided by Erik Samwell and William Van Drent from ADE Technologies. The first talk was a detailed description by Erik of the highly successful Model 10 VSM. This instrument has a possible maximum applied field of 3T and a full vector capability, including advanced analysis software to determine the actual 2-dimensional direction of magnetic moments. This instrument has become very popular and is probably the main instrument used for the characterisation particularly of perpendicular media and other magnetic systems. The proof of this pudding is the fact that at the time of the Kalamata meeting I had just ordered one!
The last talk in the session by William Van Drent also related to perpendicular media since it concerned the characterisation of such systems using MOKE. William described a fully automated system that ADE now offered in which discs are loaded into the MOKE and then scanned to determine their hysteresis loop. Of course the same system can be used for production testing of head wafers and MRAM as well as media. However, MOKE has particular advantages for characterising perpendicular media since it can be operated in polar mode so that the soft underlayer is not sensed by the instrument.
Thus overall a diverse and highly interesting session relating to leading edge metrology.
It is often said that people remember where they were when momentous historic events occurred. On the 12 September Des Mapps and I will always remember where we were when England won the Ashes! (This is the trophy for the winner of the test cricket series between England and Australia, and has a long and hoary tradition – PCH)
3. Alternative Technologies - P C Hariharan
The session on Alternative Technologies featured 9 talks in addition to the overview. Derived from scanning probe microscopy, a number of variants of probe storage have been proposed and prototyped: atomic force by the IBM group in Zurich, and magnetic force by, among others, Leon Abelman of Twente, the Netherlands. There is stiff competition in the market place from both flash memory and microdrives.
Professor Peter Rentzepis of UC Irvine presented an interesting account of two-photon recording. Although Maria Goeppert-Mayer had outlined the principle in 1932, practical realization had to await the availablilityavailability of lasers. Both two-photon storage, and holographic storage, fall into the category of volume storage.
Dr Hideyoshi Horimai of Optware outlined a novel collinear holographic storage technique using media of the same format as DVD.
Dennis Speliotis, on behalf of Jimmy Zhu of Carnegie-Mellon University, surveyed the field of MRAM. Jimmy likes ring structures for the individual MRAM elements because they are demagnetization-free, they have no sub-minimum features, and they are more tolerant to fabrication. MRAM claims many potential advantages over other electronic memories, but it appearslooks that FLASH is running away from the pack. In part the reason for this is that the technology and the facilities for fabricating FLASH are very similar to thoseat used for DRAM and SRAM. Therefore, if the market for conventional DRAM and SRAM chips becomes soft, the manufacturers can quickly switch to FLASH. This is proving to be an enormous economic advantage for FLASH.
Theoretical work on bubble domains in disc-shaped ferromagnetic particles was the subject of a presentation by Stavros Komineas of Cambridge University. He concluded that magnetic particles with strong perpendicular anisotropy can sustain high symmetry bidomain and multidomain states.
David Pappas, the final speaker in this session, spoke about quantum storage in the solid state.
Dr Dimitris Niarchos, Director of the Demokritos R&D Center in Athens, Greece (the largest research center in new technologies in Greece). They are working on high Ku materials fabrication and characterization, and more specifically on Fe(Co)Pt nanoparticles, using multilayer precursors, cluster gun, chemical synthesis, and SOMA. In addition to the fabrication methods, he described the magnetic and structural properties of these particles. Epitaxial growth of FePt on single crystal MgO at elevated temperatures produced films with perfect perpendicular texture and controlled microstructure.
4. Head/Media Interface and Tribology - Peter Baumgart, Hitachi Research –
The session dedicated to Head-Disk Interface and Tribology of HDDs was organized by Peter Baumgart of Hitachi GST Research in San Jose, CA. The opening overview presentation by Peter Baumgart titled "Approaching the Physical Limits of Head-Media Spacing in Magnetic Recording: How low can we go?" set the stage by describing and motivating the quest for ever- decreasing spacing. The presentation outlined in detail the current state of technology for magnetic spacings approaching 10 nm, as well as future needs and technology options for recording densities in the range of 1 Tb per square inch and beyond.
V. Raman of Hitachi GST summarized the "Physico-Chemical Aspects of Low Flying Head-Disk Interfaces in Magnetic Recording" and demonstrated with concrete examples the close relationship and interdependence of mechanics, dynamics, and chemistry when physical spacings approach a few nanometers.
Erhard Schreck of Maxtor delivered a presentation for Dave Fowler of Maxtor, who could not attend, titled "Challenges for 1 nm Clearance, Non-Contact HDI Designs," again stressing the issues of extremely small spacings and their challenges for a reliable HDD, especially for new applications of HDDs with extreme environmental requirements, such as automobiles, novel portable applications, etc., but declared the challenge of a reliable 1 nm physical separation as achievable.
In the final presentation of this session, Erhard Schreck covered his area of expertise: "HDI diagnostics in Disk Drives," and demonstedrating how the disk drive itself can be used as an intelligent self-monitoring diagnostic tool of its own behavior and health. He showed how critical it can be for the longevity and reliability of the head-disk interface to minimize the stress and wear-out by using properly designed algorithms for the actuator while the drive is idle. He closed with an intriguing investigation of Operating System “'personalities”' which issue differing command patterns to HDDs and thus potentially affecting their longevity in different ways. This is an area of future research and optimization, where guidelines for system integrators or HDD read/write buffer designs could be developed.
5. Advanced Heads for Perpendicular Recording, HAMR, Discrete Track and Discrete Bit -
This session included talks and discussion on write head designs for perpendicular design. Advanced designs for write heads were covered by three authors who generally agreed that 500Gb/in.2 was approximately the limit for conventional perpendicular recording. To obtain this density, optimized shielded designs (down-track and side) would need to be used. Head design for micromagnetic writing on exchange spring media was also covered. Extensions to perpendicular recording focused on Heat Assisted Magnetic Recording (HAMR). A HAMR head with an optically focused heat source integrated on a slider with field delivery could extend areal density by an order of magnitude. The physics of HAMR writing was also covered.
Read Heads were covered in three of the talks. Sining Mao said that TMR is a mature and capable reader technology for Seagate and is being integrated into all product platforms, and that extensions of the technology look promising. It was also generally agreed that at high areal densities (> 500Gb/in.2) new approaches, such as CPP Multi-layer, may be needed.
6. Micromagnetics - Manfred Schabes, Hitachi –
In the first talk, professor Fidler discussed fully integrated micromagnetic simulations, where the magnetization dynamics is solved concurrently for the write-head, the media, and the soft underlayer via advanced finite-element techniques. A study of the energetics of pinned domain walls in percolation media was then presented. These media were constructed to have defects of sizes in the range of 2 to 6 nm. The energy barriers that are created at the defects through domain-wall pinning were generally smaller than 3 kBT at 300 K, except for large film-thickness (16 nm) and large defect diameter (6 nm), where the barrier was computed to be 81 kBT. In general, the size of the defect has to be comparable to the domain-wall width in order to create sufficient pinning barriers.
In the second talk, Dr. Schabes discussed the foundations of micromagnetic simulations for multi-Tera bit/in2 materials/devices. He pointed out that the ratio of surface-to-volume generally increases for grains and devices at ultra-high bit-densities. Furthermore, it becomes important to better understand the physics at interfaces and defects. Micromagnetic calculations of the magnetization dynamics during flux-rise and flux-decay in a trailing-shield perpendicular pole head demonstrated a large range of spatial and temporal scales and their coupling. It was shown that the write-flux rises relatively slowly with time- constants of order 500-750 ps, and the temporal profile of flux-decay contains regions with reduced slope. In the second part of the presentation, coarse-grained molecular dynamics was proposed as a means to treat multi-scale Hamiltonians for multi-physics problems, i.e. where it is necessary to directly link micromagnetics with atomistic variables.
7. Magnetic Tape - Ted Schwarz, Peregrine Recording Technologies –
Magnetic tape's demise as a storage medium has been predicted for more than 30 years. Today it still remains the pre-eminent choice for the lowest cost long-term archiving and mass storage. It appears that it will probably remain so in the foreseeable future. The Tape Session presented the status of tape efforts in Europe, advances in the development of thin film media and GMR heads to support much higher areal recording densities, and advances in helical and linear scanning to achieve tens of terabytes of data storage in a single data cartridge.
8. New Magnetic Horizons - Dennis Speliotis, ADE Technologies
Des Mapps of Plymouth University described the fabrication, the properties, and the methodology of using FeBSiC alloy thin wires encapsulated in a glass coating (20 micron wire core and 5 micron glass coating) as magnetic sensors. These structures have moderate coercivities of about 45 Oe, so that they aredo not get easily disturbed by extraneous signals. The advantage is extremely low cost (about 0.0005 Euro for a 5 mm sensor of this type).
David Pappas of NIST/Boulder talked about arrays (up to 256 elements or more) of AMR sensors that can be used for a large variety of applications: a. Magnetic tape forensics, b. Data recovery; c. Biomagnetic imaging; d. Nondestructive testing of chips and devices: map the emanating magnetic fields and determine the currents flowing in the devices by deconvolution. The range of applications is enormous!
Dennis Speliotis of ADE presented a talk prepared by Bob White of Stanford University, who is working with Shan Wang, also of Stanford, to apply nanotechnology for high sensitivity DNA fragment detection. They use sub-micron arrays of magnetic field detectors to detect the field generated by small numbers of magnetic nanoparticles. This approach has extraordinary sensitivity and huge potential for the identification of DNA fragments for medical applications. Also, body fluids can be scanned to detect infectious organisms, bacteria, viruses, and terror agents. Applications such as the above can open new and vast horizons for magnetics research, applications, and markets!
9. Technology, History, Culture - Giora Tarnopolsky, Tarnotek and INSIC