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A Way Forward Not necessarily The Way Forward

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A Way Forward? (Not necessarily 'The Way Forward') J N Chapman, University of Glasgow ... Ceramic Insulated, Nickel plated copper windings. 300N, 0.5mm stroke ... – PowerPoint PPT presentation

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Title: A Way Forward Not necessarily The Way Forward


1
A Way Forward?(Not necessarily The Way Forward)
  • J N Chapman, University of Glasgow
  • Synopsis
  • Indicators of activity
  • Magnetism in the late 20th century
  • A firm base within the UK?
  • Some possible ways ahead

2
Hard Disc Drive Performance
3
The Permanent Magnet Market
4
Bonded Magnet Production
5
International Magnetics Conferences 1999
  • MORIS NdFeB 99
  • Hard ferrite magnets ISEM
  • Intermag TMRC
  • Soft magnetic materials TISD
  • Int Conf on Electrical Machines and Drives
  • Major sessions at
  • MRS APS
  • COMPUMAG ISEF
  • In the 3 months leading up to this conference,
    Magnews listed 37 conferences!

6
Articles in Physics World related to Magnetics-
1999 and 1992
  • January - June 1999
  • Europe plans magnet facility (1/99)
  • Thin films squeeze out domains (1/99)
  • Colossal magnetoresistance (2/99)
  • Spinning electrons could lead electronics
    revolution (3/99)
  • Magnets, molecules and quantum mechanics (3/99)
  • Magnetoelectronics (4/99)
  • Weak ferromagnet challenges theorists (4/99)
  • Faster magnetic memory (6/99)
  • January June 1992
  • Are environmental magnetic fields dangerous
    (1/92)
  • Fundamental effects in a spin (5/92)

7
What the Papers Say
8
Growth of the UK Magnetics Society
9
Magnetism - a Broad Church!
  • Magnetic phenomena are studied
  • on length scales from nuclear to planetary
  • on time scales from fs to geological
  • over temperature ranges from ?K to GK
  • over field ranges from fT to gt100T
  • Magnetics runs through Physics, Chemistry,
    Materials Science, Metallurgy, Engineering, IT.
  • There are close materials links to metals and
    oxides, especially superconductors, optical
    materials and semiconductors.
  • Generic technologies of importance include thin
    films, growth processing, material
    characterisation.

10
Fundamental Physics
  • An exciting area of condensed matter science
    involving exotic metals and complex oxides
  • Close links to superconductivity
  • Extension to lower temperature and higher fields
    reveals wealth of novel behaviour (non-Fermi
    liquid behaviour, quantum fluctuations, magnetic
    quantum oscillations)
  • Magnetism in superlattices and magnetic chains
  • Interfacial phenomena
  • Interface and surface anisotropy
  • Spin dependent transport (metal-metal,
    metal-semiconductor, metal- insulator, etc.)
  • Tunneling, Coulomb blockade, spin transistor

11
Colossal Magnetoresistance
  • Based on Mn oxides with the perovskite structure.
  • Perovskite structure is natural laboratory for
    studying strongly correlated electron systems
    (coupling between electrons and lattice,
    competition between kinetic energy of mobile
    electrons and repulsive Coulomb interaction,
    etc.) control is achieved by doping.
  • Manganites are almost fully polarised.
  • Key features include the role of phonons at the
    metal/insulator transition, nature of the
    ground state, effect of interfaces on
    polarisation, phase separation, surface
    magnetisation, local disorder due to doping.
  • MR gtgt 100 in fields of a few Tesla.
  • Potential for devices? - need for good room
    temperature performance at low fields.
  • Defect-free interfaces, introduction of
    controlled defects, exploration of tunneling
    transport in complex oxides having intrinsic
    multilayer structures.

12
Magnetic states as a function of doping in
La1-xCaxMnO3
13
Giant Magnetoresistance
  • GMR arises due to spin-dependent scattering.
  • It occurs in magnetic multilayers, granular
    magnetic solids, spin-valves (SVs), spin tunnel
    junctions (STJs). SVs and STJs offer MR values of
    10-40 and sensitivities of few /Oe.
  • The basic mechanism is reasonably understood but
    detail is lacking and the GMR effect is not yet
    fully exploited (for example, effect of a domain
    wall at a point contact).
  • Application areas are sensors (recording heads,
    positional for automotive application,
    navigational, etc.) and storage (MRAMs).
  • Scientific and technological challenges include
  • layer thickness control with decreasing stack
    thickness
  • exchange biasing of the pinned layer
  • performance retention after patterning

14
Nanomagnetism
  • A branch of nanoscience and technology which
    offers
  • new phenomena as the dimensions of a magnetic
    structure fall below various characteristic
    magnetic length scales (e.g. spin diffusion
    length, domain wall width)
  • a way of tailoring magnetic properties through
    variation of the size and shape of magnetic
    elements - spin engineering
  • Scope for innovation in
  • selecting the systems to be patterned and the
    form of the resulting patterned elements
  • devising ways in which patterning is carried out
    (advanced lithographies, reactive ion etching,
    mask irradiation, probe microscopies, mass
    replication methods)
  • Technological driving forces include ultra-small
    sensors, MRAMs, quantum discs, spintronics.

15
Recording
  • Magnetic recording - hard disc and tape
  • Phenomenal growth over the last decade due to
    near-insatiable demands to store data.
  • Key issues now are what limits the density at
    which we can store information, the time
    required to write and access it and the period of
    time over which the medium retains it.
  • Challenges span materials with improved magnetic
    properties, through developing sophisticated
    micromechanical drives, to optimisation of the
    recording channel and coding.
  • As recording densities increase beyond
    70GB/sq.in, and for special applications, other
    technologies may be/are required
  • recording on perpendicular media or discrete
    media (quantum discs), magneto- optic recording,
    hybrid magnetic - MO recording, magnetic random
    access memory (MRAM)

16
MRAM cells showing architecture
17
Spintronics
  • Spintronics encompasses GMR, spin-dependent
    tunneling and spin-injection devices.
  • MRAM
  • non-volatile, radiation hard, speed of SRAM
    (lt3ns), density of DRAM, low power (0.005x), low
    cost (0.1x), infinitely cyclable
  • Coherent spin transport in semiconductors looks
    encouraging following 2 recent discoveries
  • at room temperature, optically induced
    spin-states have been found to be very long
    lived
  • ferromagnetism exists in semiconducting GaMnAs
  • Once the physics and materials aspects are
    solved, spin enhanced and enabled electronics,
    spin filters, spin FETs, quantum
    spin-electronics, coherent spin electronics are
    anticipated.

18
Control and Measurement of Material Properties
  • Control through growth conditions, processing and
    patterning
  • Final performance depends on interplay between
    intrinsic and extrinsic properties
  • Strong role for theory and modelling in a
    multi-parameter space
  • Increased need to measure both structural and
    magnetic properties as completely as possible
  • Importance of interfaces
  • Understanding and exploitation of MR phenomena
    (depolarisation of carriers in GMR and
    especially CMR materials)
  • Control of surface anisotropies (property
    control in ultra-thin films)
  • Coupling between grains in hard magnetic
    materials and ultra-high density recording media

19
Characterisation Techniques
  • In-house characterisation
  • Ultra-fast measurements (pump-probe - sub-ps)
  • High spatial resolution imaging (MFM with novel
    sensor heads, in-situ TEM)
  • Sophisticated magnetometry (micro-magnetometers,
    minor loops, time dependence over decades)
  • In-situ and ex-situ analytical techniques
    (spin-polarised techniques, STM, AFM, Auger,
    EELS)
  • Characterisation using Facilities
  • Neutrons, X-rays, Ultra-high fields

20
TEM Magnetic Images of NiFe Elements(Courtesy of
Dr K Kirk, University of Glasgow)
21
MFM images of 50nm tracks(Courtesy of Dr L
Folks, IBM)
22
Facilities
  • X-ray magnetic scattering
  • Resonant enhancement of magnetic scattering,
    element specific magnetic studies
  • Dichroism studies (circular and linearly
    polarised), x-ray microscopy
  • Separation of spin and orbit contributions to
    the magnetic behaviour of materials
  • 100T magnet - pulsed fields 10ms duration
  • Investigation of new physics along the field
    axis of the phase diagram
  • Understanding in strongly correlated electronic
    systems of the underlying many-body physics,
    including magnetic quantum critical phenomena
  • Application to high anisotropy intermetallics,
    metallic superlattices, doped oxides,
    spin-liquids

23
Permanent Magnets
  • Rare earth - transition metal magnets (Fe and
    Co-based) are the subject of most research.
  • Annual growth rate of sintered NdFeB magnets
    12, of bonded NdFeB magnets 20
  • Partly fuelled by global growth of PCs but other
    areas promising including MRI, industrial
    robotics, mobile phones
  • Largest potential is in electric vehicles
  • Challenges include
  • Materials suitable for operation at high
    temperature (180C)
  • Improved corrosion resistance
  • Cost-effective production methods, recalling
    that the microstructure dominates the properties
    of permanent magnet materials

24
Some of the Many Applications of Permanent Magnets
  • Automotive
  • Starter motors, anti-lock braking systems (ABS),
    motor drives for wipers, injection pumps, fans
    and controls for windows, seats etc,
    loudspeakers, eddy current breaks, alternators
  • Telecommunications
  • Loudspeakers, microphones, telephone ringers,
    electro-acoustic pick-ups, switches and relays
  • Data Processing
  • Discs drives and actuators, stepping motors,
    printers
  • Consumer Electronics
  • DC motors for showers, washing machines, drills,
    citrus presses, knife sharpeners, food mixers,
    can openers, hair trimmers etc., low voltage DC
    drives for cordless appliances such as drills,
    hedgecutters, chainsaws, magnetic locks for
    cupboards and doors, loudspeakers for TV and
    audio, TV beam correction and focusing device,
    compact-disc drives, home computers, video
    recorders, electric clocks, analogue watches
  • Electronic and Instrumentation
  • Sensors, contactless switches, NMR spectrometer,
    energy meter disc, electro-mechanical
    transducers, crossed field tubes, flux-transfer
    trip device,
  • Industrial
  • DC motors for magnetic tools, robotics, magnetic
    separators for extracting metals and ores,
    magnetic bearings, servo-motor drives, lifting
    apparatus, brakes and clutches, meters and
    measuring equipment
  • Astro and Aerospace
  • Frictionless bearings, stepping motors,
    couplings, instrumentation, travelling wave
    tubes, auto-compass
  • Biosurgical
  • Dentures, orthopaedics, wound closures, stomach
    seals, repulsion collars, ferromagnetic probes,
    cancer cell separators, NMR body scanner

25
Soft Magnetic Materials
  • Progress continues in FeSi and in soft amorphous
    and nanocrystalline alloys
  • The scale of use of FeSi makes reductions of loss
    of a fraction of 1 significant
  • (Fe, Co, Ni)(Si, B) plus additions are developed
    for specialist applications and there is scope
    for innovation here
  • Modelling on various length scales
    (micromagnetic, hysteresis and finite element)
    and finding ways of linking them will lead to
    more efficient machines and motors
  • Understanding how materials respond under varying
    combinations of field and stress is
    scientifically challenging and is the key to new
    and improved applications
  • Amorphous wires with near zero magnetostriction
    and with a strong negative magnetostriction offer
    exciting possibilities for many sensor
    applications through the giant magneto-impedance
    and the stress impedance effect

26
Machines, Drives and Actuators
  • Improved performance, increased energy efficiency
    and the enabling of applications not previously
    possible is being realised with the help of
  • advanced magnetic materials
  • powerful design and analysis programmes
  • Examples of innovation include
  • embedded machines in aero engines operating at
    high temperatures, with magnetic bearings
    replacing mechanical bearings
  • soft, high-resistivity composites for magnetic
    bearings running at up to 60,000rpm in vacuum
    with appropriate magnetic circuit design
    hysteresis is almost eliminated and losses are
    minimised
  • multi-degree of freedom actuators incorporating
    high energy product magnets and operating at
    200Hz for force feedback joysticks usable in
    surgery and other active vision systems,
    including computer games

27
Innovations in Machines(Courtesy of Dr G Jewell
and Professor D Howe, University of Sheffield)
  • High Temperature (800oC) Linear Actuator
  • 24 Cobalt Iron
  • Ceramic Insulated, Nickel plated copper windings
  • 300N, ?0.5mm stroke
  • Linear permanent magnet actuator
  • for textile machinery
  • 200mm stroke
  • Peak acceleration of 100g

28
Innovations in Machines(Courtesy of Dr G Jewell
and Professor D Howe, University of Sheffield)
  • Aerospace Electrohydraulic surface actuator
  • Technology Demonstrator for Airbus A3XX
  • 55kW, Brushless NdFeB Permanent Magnet Motor
  • Brushless Permanent Magnet Machine
  • 120,000rpm (100mm OD)
  • Carbon Fibre / NdFeB / Epoxy composite rotor

29
Magnetics in the United Kingdom
  • There are scientific, technical and engineering
    opportunities in profusion - how can the UK take
    best advantage?
  • UK background
  • The total number of workers in academia and
    industry in magnetism is considerable (for
    example, there are ?500 academic researchers).
  • With a few notable exceptions, activity is
    concentrated in small units in industry and
    academia.
  • There is a danger of sub-criticality.
  • Collaboration and networking are seen as the
    best way of avoiding the danger of
    sub-criticality.

30
Organisations with an Interest in Fostering the
Advancement of UK Magnetics
  • Learned societies and industrial clubs/trade
    associations - IoP, IoM, IEE, IEEE, UK MagSoc,
    TRIUMF. (for example Joint Magnetics Workshop)
  • DTI (LINK scheme in Storage and Displays, UKISC)
  • Foresight
  • Seagate Technology Plan
  • Europe Framework 5 (opportunities for links to
    elsewhere in Europe)
  • EPSRC

31
Possible LINK in Information Storage and Display
  • Objectives
  • Encourage new links between companies and
    science engineering base
  • Involve gt 20 organisations (including gt 10 SMEs)
    in collaborative projects
  • Stimulate exploitation of academic research
  • Encourage supplier-user and small - large
    company relationships
  • Develop UK information storage community
  • Proposed budget
  • 8M plus matching funds from industry
  • Proposed launch
  • End 1999/beginning 2000

32
EPSRC (I)
  • Magnetism and Magnetic Materials Initiative (1989
    - 1994)
  • Advanced Magnetics Programme (Physics and
    Materials) - due to end 2000
  • Machines and Drives (Engineering) - ended 1998
  • Responsive mode (notable take-up in fundamental
    condensed matter physics) - continuing
  • What next?
  • The next 6 months provide an opportunity for you
    to advise programmes managers of what you would
    like to happen and why!

33
EPSRC (II)
  • Another managed programme?
  • Bad fit to current EPSRC policy but would
    protect those aspects of the programme at the
    physics/materials materials/engineering
    interfaces which arguably contain some of the
    most exciting possibilities for the future.
  • Return to responsive modes in Physics, Materials
    and Engineering?
  • Encourage EPSRC to ensure that assessment panels
    are chosen which contain representatives from
    more than one programme area.

34
EPSRC (III)
  • If there is no EPSRC coordinator, will the UK
    (academic) magnetics community fragment?
  • Suggestion
  • Establish EPSRC Networks involving both
    academics and industrialists.
  • Use these as fora to decide (non-exclusive)
    priorities for different aspects of magnetics.
  • Set aside some of final round of AMP money to
    fund these.
  • Purpose
  • Help carry forward existing collaborations and
    provide springboard for new ones so that small
    individual groups can make maximum impact.
  • Provide a harmonious way to keep UK magnetics
    competitive and at the leading edge.

35
Conclusions
  • At the end of the 1980s UK magnetics was weak
    at the end of the 1990s this is no longer the
    case.
  • The momentum and cohesion built up over the last
    decade must not be allowed to evaporate.
  • A diffuse non-interacting academic community will
    never maintain a high profile with government,
    industry, EPSRC and is unlikely to make an impact
    internationally.
  • Significant organisational change (for academics
    at least) is inevitable in the next 12 months but
    there is a short time window open to try to
    influence the nature of the change this
    opportunity must be taken!
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