Selected Topics in Physics – Prof. K. Franke: From basic research to applications in solid state physics.

Talk given by Olof Peters June 4, 2013

Giant

The Begin of – Awarded with the Nobel Prize in Physics 2007 In 2007 the Nobel Prize in Physics was awarded to the Frenchman and the German Peter Gr¨unberg for the discovery of the Giant Magnetoresistance (GMR) effect. The direct application of this new technology was quickly identified in building a new type of reading heats for hard disks. Not even ten years after the discovery of the new technology the first commercial GMR-head was produced in 1997 and became the stan- dard in technology. GMR meant a breakthrough for reading tightly packed informations from hard disks and lead the way to the age of smartphones and tablets, which become always smaller although their storage space increases. In this sense GMR is a good example of how an unexpected fundamental scientific discovery can quickly give rise to new technologies and commercial products.

The talk of course aims to giveI NFORMAT a introductionI ON FOR THE PUBLI C to the concept of Giant Magnetoresis- tance, including a short introduction to magnetoresistance and the physics of magnetic Themultilayer Nobel systems. Prize Besides in Physics the obvious 2007 application for reading heats the presentation will give a short overview of the so called magnetoelectronics or spintronics, where GMR This year’s Nobel Prize in Physics is awarded to ALBERT FERT and PETER GRÜNBERG for their disco- veryplayed of Giant Magnetoresistance. the role Applications of a of doorthis phenomenon opener. have revolutionized Spintronics techniques for is today one of the driving forces for new retrieving data from hard disks. The discovery also plays a major role in various magnetic sensors as well asapplications for the development of a new in generation of electronics. The use of Giant Magnetoresistance and the can talk be will show this by the example of the devel- regardedopment as one of the of firsta major magnetic applications of nanotechnology. working memory so called MRAM, which provides the advantage Betterto combine read-out aheads permanent for pocket-size memory devices with the speed of today’s random access memories. Constantly diminishing electronics have become a matter of course in today’s IT-world. The yearlySo addition after to the the market presentations of ever more powerful and lighter of computers quite is something a lot we newhave kinds of electronics during the series of our all started to take for granted. In particular, hard disks have shrunk – the bulky box under your desktalks, will soon be like history forwhen the example same amount of data in can”Graphene just as easily be stored in field-effecta slender transistors” and ”Photonic Crystals”, laptop. And with a music player in the pocket of each and everyone, few still stop to think about howthis manytalk cds’ worth will of music offering its tiny hard disk another can actually hold. very Recently, interestingthe maximum one. storage capacity of hard disks for home use has soared to a terabyte (a thousand billion bytes).

Areal density (gigabits/cm 2 ) 100

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0.001 MR GMR

1980 1990 2000 2010 Year

Diagrams showing the accelerating pace of miniaturization might give a false impression ofLeft: simplicity – A as ifpicture this development of followed an a law actual of nature. In hard actual fact, disk the ongoing with reading head. The diagram showing the IT-revolution depends on an intricate interplay between fundamental scientific progress and 1 technicalaccelerating fine tuning. This ispace just what the of Nobel miniaturization Prize in Physics for the year 2007 is in about. information technology ; Right: Scheme of a MRAM2.

The Nobel Prize in Physics 2007 • The Royal Swedish Academy of Sciences • www.kva.se 1(7)

1Royal Swedish Academy of Sciences. The Nobel Prize in Physics 2007 – Information for the Public, October 2007 2URL http://www.colorado.edu/physics/phys3220/phys3220_sp05/images/ftjm.jpg