quantum hall effect l.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Quantum Hall Effect PowerPoint Presentation
Download Presentation
Quantum Hall Effect

Loading in 2 Seconds...

play fullscreen
1 / 11

Quantum Hall Effect - PowerPoint PPT Presentation


  • 524 Views
  • Uploaded on

Quantum Hall Effect. Jesse Noffsinger Group Meeting Talk (As required by the Governor of the State of California) April 17, 2007. Classical Hall Effect. Experimental Values *. B. +++++++++++++++++++. E x , j x. V H. E y. - - - - - - - - - - - - - - - - - - . *Ashcroft and Mermin.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Quantum Hall Effect' - happy


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
quantum hall effect

Quantum Hall Effect

Jesse Noffsinger

Group Meeting Talk

(As required by the Governor of the State of California)

April 17, 2007

classical hall effect
Classical Hall Effect

Experimental Values*

B

+++++++++++++++++++

Ex, jx

VH

Ey

- - - - - - - - - - - - - - - - - -

*Ashcroft and Mermin

slide3

Integer QHE

Discovered in 1980,

Nobel Prize awarded to von Klitzing in 1985

aa

SEM image of a Hall bar*

*Georgia Tech physics website

slide5

Degeneracy of Landau Levels

Each wavefunction is centered at

Energy

DOS:

Increasing B

slide6

Impurity Effects

Isolated -fn potential localizes one extended state

Only extended

states carry current!

Extended States

E

Localized States

DOS

slide7

The Laughlin Argument for the Integer Hall effect

Form a closed loop w/ Hall bar

Change the flux through the loop by one quanta:

No change can take place in the bulk –

move one electron to the other edge

p must be an integer

fractional qhe
Fractional QHE

Filling factor is a rational fraction

Cannot be explained in

terms of free electrons

slide9

Composite Fermion Picture

ElectronsIQHE

Composite FermionsFQHE

Fractional Hall effect encompasses states with filling factors:

Composite fermions can be viewed as electrons with attached flux quanta

is screened to

slide10

Lowest Landau level splitting for composite fermions

Energy

v=1 lowest Landau Level splits into levels separated by

The fractional filling of electrons is really the integral filling of composite fermions

slide11

Conclusion

  • Integral Quantum Hall effect can be accurately modeled as
  • a non-interacting electron gas in a magnetic field
  • The Fractional Quantum Hall effect involves composite fermion
  • quasi-particles which are electrons with attached flux quanta