Physicists reveal first images of Landau levels

Oct 01, 2012
First images of Landau levels revealed
This shows experimentally measured Landau Level 1. Credit: University of Warwick

Physicists have directly imaged Landau Levels – the quantum levels that determine electron behaviour in a strong magnetic field – for the first time since they were theoretically conceived of by Nobel prize winner Lev Landau in 1930.

Using scanning tunnelling spectroscopy - a spatially resolved probe that interacts directly with the electrons - scientists at institutions including the University of Warwick and University have revealed the internal ring-like structure of these Landau Levels at the surface of a semiconductor.

The experimental challenge in the work was to have sufficient in order to overcome the intrinsic disorder in the material which usually only allows the observation of smeared out "drift" states.

The images clearly show that Landau was right when he predicted that, in a clean system, the electrons would take on the form of concentric rings, the number of which increase according to their .

First images of Landau levels revealed
This shows numerically simulated Landau Level 1. Credit: University of Warwick

This simple counting behaviour forms the basis of the so-called .

While originally of mostly fundamental interest, the effect has in recent years been used to define the standard for what we mean by and could soon be employed to define the kilogram as well.

Professor Rudolf Roemer of the Department of Physics at the University of Warwick said: "This is an exciting step for us, we are really seeing for the first time individual quantum mechanical wave functions of electrons in real materials.

"On the face of it this might seem far removed from everyday life.

"However the question of what defines a kilogram is currently being debated, with the spacing between the rings of these Landau levels acting as a kind of marker for a universal weight.

"So next time you measure out your sugar to bake a cake, you might unknowingly be making use of these quantum rings."

The research, Robust Nodal Structure of Landau Level Wave Functions Revealed by Fourier Transform Scanning Tunneling Spectroscopy, was published in the journal Physical Review Letters.

Explore further: Cold Atom Laboratory creates atomic dance

More information: Citation: Phys. Rev. Lett. 109, 116805 (2012)

Related Stories

Observing the Quantum Hall Effect in 'Real' Space

Jan 12, 2009

(PhysOrg.com) -- When water transforms into steam, or magnetized iron changes to demagnetized iron, Katsushi Hashimoto explains to PhysOrg.com, a phase transition is taking place: “Classical phase transitions…often share ...

Redefining the kilogram and the ampere

Sep 29, 2011

New research using graphene presents the most precise measurements of the quantum Hall effect ever made, one of the key steps in the process to redefine two SI units.

Recommended for you

Cold Atom Laboratory creates atomic dance

8 hours ago

Like dancers in a chorus line, atoms' movements become synchronized when lowered to extremely cold temperatures. To study this bizarre phenomenon, called a Bose-Einstein condensate, researchers need to cool ...

Scientists create possible precursor to life

15 hours ago

How did life originate? And can scientists create life? These questions not only occupy the minds of scientists interested in the origin of life, but also researchers working with technology of the future. ...

Superconducting circuits, simplified

Oct 17, 2014

Computer chips with superconducting circuits—circuits with zero electrical resistance—would be 50 to 100 times as energy-efficient as today's chips, an attractive trait given the increasing power consumption ...

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

Tausch
1 / 5 (1) Oct 02, 2012
The experimental and the numerically simulated Landau levels display differences.
Are the differences insignificant or attributed to insignificance factors?