bryan chávez university of south carolina, physics and...

Bryan ChávezUniversity of South Carolina, Physics and Astronomy

Graduate SeminarSeptember 19, 2014

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Introduction to 2007s Physics Nobel Early Years Giant Magnetoresistances (GMR) Spintronics Applications Conclusion

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Awarded: "for the discovery of Giant Magnetoresistance”

Awarded to: Albert Fert and Peter Grünberg Actually discovery was in 1988

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Spin wave experiments done by Peter Grünberg

Done through Raman Light Scattering

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Look at how an electronmoves through a magneticmultilayer The two magnetic layersare Fe(~12nm) with Cr(~1nm) in between

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First Theoretical theory for Giant Magnetoresistance

Based on Boltzmann’s diffusion equation

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Original experiment had the current in plane with the multilayer

Spintronics is based off of current perpendicular to plane of multilayer

currentcurrent

Current Perpendicular to Plane

Current In Plane10

Giant Magnetoresistance leads to spintronics Moved away from dealing with charge to deal

with electron spin Conventional circuit analysis deals with bulk

charge through current Spintronics attempts to manipulate the spin

of an electron

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The barrier between the Fe and the spacer causes an accumulation of spins

If you have an anti-parallel B field on the other side it produces a torque

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Similar to Light Polarization

J. Slonczewski, JMMM 1996, L. Berger, PR B 199613

Current Perpendicular to Plane effect with an insulator instead of conductor

Can be used as switches or to store data

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Magnetic Sensors Tunneling Switches Magnetic Random Access Memory

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Currently used on hard drives and lead to the ability to make 1 terabyte drives

Used to measuring small magnetic fields

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Tunnel junctions can be used as switches or to store data

To switch a junction the B field needs to be ~100 Oe = 0.01 Telsa = fridge magnet

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Uses the Tunnel junction to store data in a matrix

Possibly to replace all current forms of memory storage

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Ferromagnetic semiconductors Spin transfer oscillators Phone gaussmeters Traffic control sensors

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Giant Magnetoresistance has change the way electronics are thought about

Giant Magnetoresistance has lead to great advance in out understand of the manipulation of electron spins

Spintronics is wide open to many new advance to help us in computing

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Fert, Albert. The Origin, devolopment and future of spintronics. 2007.Grünberg, Peter. From spinwaves to Giant Magnetoresistance (GMR)

and beyond. 2007.Rodgers, Peter. Nanoscience And Technology : A Collection Of Reviews

From Nature Journals. Singapore: World Scientific, 2010. eBook Collection (EBSCOhost). Web. 18 Sept. 2014.

Xia, Jianbai, Kai Chang, and Weikun Ge. Semiconductor Spintronics. Singapore: World Scientific, 2012. eBook Collection (EBSCOhost). Web. 18 Sept. 2014.

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