phd thesis, claudiu daniel stanciu
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PhD thesis, Claudiu Daniel Stanciu. Radboud University Nijmegen, The Netherlands (2004 - 2008) (now working at Océ Technologies). Over 110 years of Magnetic Recording. The first working magnetic recorder ( 1898 ). The first magnetic tape ( 1928 ). Telegraphone (by Valdemar Poulsen). - PowerPoint PPT PresentationTRANSCRIPT
Radboud University Nijmegen
PhD thesis, PhD thesis, Claudiu Daniel StanciuClaudiu Daniel Stanciu
Radboud University Nijmegen, The Netherlands (2004 - 2008)Radboud University Nijmegen, The Netherlands (2004 - 2008)(now working at Océ Technologies)(now working at Océ Technologies)
Radboud University Nijmegen
Over 110 years Over 110 years of Magnetic Recordingof Magnetic Recording
Telegraphone (by Valdemar Poulsen)
The first working magnetic recorder (1898)
The first hard disk drive – HDD (1955)
5MB memory storage (IBM)
The first magnetic tape (1928)
Magnetophon (Fritz Pfleumer)
The first magnetic core memory (late 1940’s)
IBM
Radboud University Nijmegen
Magnetic Recording Devices Magnetic Recording Devices TodayToday
The first hard disk drive – HDD (1955)
5MB memory storage (IBM)
Hard disk drive – HDD (2010)
5GB memory storage
Radboud University Nijmegen
MagneticMagnetic DataData Storage Storage
Hard Disk Drive(HDD) 0 1 1 0
Magnetic Bits
Magnetic domains in a HDD
- black areas- black areas - white areas- white areas
Radboud University Nijmegen
ChallengesChallenges in Magnetic Data Storage in Magnetic Data StorageHigher and higher bit density Higher and higher data storage speed
FASTER switching speedof the tiny magnets
SMALLER magnetic areas(tinier magnets)
This thesis focuses on the speed of the magnetization switchingThis thesis focuses on the speed of the magnetization switching
“By 2012, just two disks will provide the same storage capacity as the human brain!”
Robert Birge (Syracuse University)
~ 10 Terabyte ~ 10 Terabyte
FAST!FAST!
Radboud University Nijmegen
??
How to How to SwitchSwitch a Magnet…? a Magnet…?
Radboud University Nijmegen
ConventionalConventional Magnetic Data Magnetic Data StorageStorage
11 00 11 00 0011 11 11
The conventional way The conventional way of reversing magnetizationof reversing magnetization
is by applying an external magnetic field.is by applying an external magnetic field.
Radboud University Nijmegen
Initial Initial statestate
Final Final statestate
How FastHow Fast a Magnet a Magnet can becan be SwitchedSwitched……??
Today, the time it takes to switch a magnet in is ~ 700ps
The The speedspeed of this process is of this process is proportionalproportional withwith the strength of the strength of the applied magnetic fieldthe applied magnetic field..
The switching speed The switching speed may be as high as desiredmay be as high as desired
provided sufficiently high fields are available!?provided sufficiently high fields are available!?~ 700ps
Is there any speed limit?Is there any speed limit?
Radboud University Nijmegen
““No matter how short and strong the magnetic-field pulse, No matter how short and strong the magnetic-field pulse, magnetic recording cannot be made ever faster than picoseconds.”magnetic recording cannot be made ever faster than picoseconds.”
The Ultimate Speed Limit: The Ultimate Speed Limit: a few Picosecondsa few Picoseconds
Magnetic field pulses: 2.3 picoseconds, 3 Tesla
3 km long Stanford Linear Accelerator in California
The shortest and strongest magnetic field on the Earth
In 2004…In 2004…
Radboud University Nijmegen
New ChallengeNew Challenge in Magnetic Data Storage in Magnetic Data Storage
Find novel waysFind novel ways to reverse magnetization to reverse magnetization
faster than picosecondsfaster than picoseconds
Radboud University Nijmegen
The dreamThe dream
What if light could reverse What if light could reverse Magnetization?Magnetization?
Opto-MagneticOpto-MagneticRecordingRecording
Use Light Use Light PulsePulse: One of : One of the the shortest shortest man-made man-made
eventevent
Unimaginable Unimaginable storage storage speeds:speeds:
100THz and 100THz and moremore
Light could not only Light could not only transfer but store transfer but store the information toothe information too
Radboud University Nijmegen
Magnetization changes the polarization of lightMagnetization changes the polarization of light
SpinsSpins PhotonsPhotons
Controlling magnetization by lightControlling magnetization by light
Magneto-OpticsMagneto-OpticsOpto-MagnetismOpto-Magnetism
??Opto-magnetismOpto-magnetism
MM
MM
(-)(-)
(+)(+)
Inverse Faraday effectInverse Faraday effect
Magneto-opticsMagneto-optics
EE
EE
F F ~M~Mzz
MMzz
Faraday effectFaraday effect
Radboud University Nijmegen
Is all-optical magnetization reversal feasible?Is all-optical magnetization reversal feasible?
““The amount of the photons involved in the experiments The amount of the photons involved in the experiments is far not enough to contribute a significant angular momentum.”is far not enough to contribute a significant angular momentum.”
““In metals, electron-electron scattering appears to make coherent In metals, electron-electron scattering appears to make coherent manipulation of magnetization difficult if not impossible.”manipulation of magnetization difficult if not impossible.”
J. Stohr, H. C. Siegmann J. Stohr, H. C. Siegmann Magnetism: From Fundamentals to Nanoscale Dynamics,Magnetism: From Fundamentals to Nanoscale Dynamics, Springer 2006 Springer 2006
“… “… one cannot expect to induce coherent electron spin one cannot expect to induce coherent electron spin dynamics in metals with laser pulses of 30 fs duration.”dynamics in metals with laser pulses of 30 fs duration.”
Radboud University Nijmegen
Ultrafast opto-magnetic recording…?Ultrafast opto-magnetic recording…?
Speed limit?Speed limit?
Not enough photons?Not enough photons?
Electron-electron scattering a problem?Electron-electron scattering a problem?
Literature says:Literature says:Ultrafast opto-magnetic recording is IMPOSSIBLE!Ultrafast opto-magnetic recording is IMPOSSIBLE!
Radboud University Nijmegen
……we never say we never say NEVERNEVER……
Radboud University Nijmegen
Experimental set-upExperimental set-up
Metallic amorphous alloyMetallic amorphous alloyGdFeCoGdFeCo
typically used intypically used indata storagedata storage
Circularly polarizedCircularly polarizedlaser pulseslaser pulses
Quarter waveQuarter waveplateplate
Linear polarizedLinear polarizedlaser pulseslaser pulses
Magneto-OpticalMagneto-Opticalmicroscopemicroscope
Amplified Ti:Sapphire Amplified Ti:Sapphire laserlaser, 1 KHz, , 1 KHz, 40 fs40 fs and 800 nm and 800 nm
Before laserBefore laserexcitationexcitation
GdFeCo thin filmGdFeCo thin film
Magneto-Optical imageMagneto-Optical image
Radboud University Nijmegen
Opto-magnetic recordingOpto-magnetic recording
100100mm
HHextext = 0 = 0Material: GdFeCo,Material: GdFeCo,40 fs pulses at 1kHz40 fs pulses at 1kHz
C.D. Stanciu et al,, C.D. Stanciu et al,, Phys. Rev. Lett. 98, 207401 (2007) Phys. Rev. Lett. 98, 207401 (2007) C.D. Stanciu et al., C.D. Stanciu et al., Phys. Rev. Lett. 99, 047601 (2007)Phys. Rev. Lett. 99, 047601 (2007)
Radboud University Nijmegen
Sweeping the pulsed laser beam at high speed across the sampleSweeping the pulsed laser beam at high speed across the sample
Each domain is written with a Each domain is written with a singlesingle 40 fs laser pulse 40 fs laser pulse
Braking the speed limit of magnetic recording with an Braking the speed limit of magnetic recording with an effect previously believed impossible!effect previously believed impossible!
With a single 40 fs laser pulse?With a single 40 fs laser pulse?
Opto-magnetic recordingOpto-magnetic recording
Radboud University Nijmegen
Writing time ~ 1 ns
Switching Magnets with Magnetic FieldSwitching Magnets with Magnetic Field
~ 1 GHz
Switching Magnets with Light PulsesSwitching Magnets with Light Pulses
Writing time ~10 fs ~ 100 THz
Traditional Magnetic RecordingTraditional Magnetic RecordingUltrafast Opto-Magnetic RecordingUltrafast Opto-Magnetic Recording
~50.000 faster than the actual speed of a Hard Disk Drive
Radboud University Nijmegen
Femtosecond Femtosecond is one quadrillionth of a second, is one quadrillionth of a second, and 40 femtoseconds and 40 femtoseconds
is all it takes for a bit of data to be written is all it takes for a bit of data to be written to a magnetic materialto a magnetic material.
Thank you for your attention!
&
Thank you UMICORE and FWO!