Synopsis: Spin-polarized fractional quantum Hall effect

Fractional quantum Hall effect is observed in a new system, a CdTe quantum well with strong intrinsic Zeeman energy.
Synopsis figure
Credit: Adapted from B. A. Piot et al., Phys. Rev. B (2010)

The fractional quantum Hall effect (FQHE) is a well-known collective phenomenon that was first seen in a two-dimensional gas of strongly interacting electrons within GaAs heterostructures. The system behaves at very low temperatures and high magnetic fields as if it were composed of particles with fractions of the elementary charge and exhibits a series of plateaus in the Hall resistance at fractional filling factors (ratio of number of electrons to the magnetic flux quanta). Subsequently, FQHE has also been observed in ultraclean, suspended graphene, also a two-dimensional system but with a difference: electrons in graphene behave as massless chiral fermions.

In an article appearing in Physical Review B, Benjamin Piot from Laboratoire National des Champs Magnétiques Intenses, Grenoble, France, and collaborators from the Czech republic, Germany, and Poland report the first observation of the fractional quantum Hall effect in a high-mobility CdTe quantum well at millikelvin temperatures. CdTe is a single valley, direct gap II-VI semiconductor in which the bare electronic g factor is about four times larger than in GaAs . That results in a relatively high intrinsic Zeeman energy that can overcome the Coulomb energy to align the spins with the magnetic field and display fully developed FQH states in the upper spin branch of the lowest Landau level. A significant advantage of this system is the possibility of incorporating magnetic ions to form a diluted magnetic semiconductor for possible applications in spintronics and also to study the many-body effects in the presence of high Zeeman energy. – Sarma Kancharla


Announcements

More Announcements »

Subject Areas

Semiconductor Physics

Previous Synopsis

Semiconductor Physics

A bumpy road

Read More »

Next Synopsis

Superconductivity

Unconventional pairs

Read More »

Related Articles

Focus: <i>Landmarks</i>—Accidental Discovery Leads to Calibration Standard
Semiconductor Physics

Focus: Landmarks—Accidental Discovery Leads to Calibration Standard

The quantum Hall effect, discovered unexpectedly 35 years ago, is now the basis for defining the unit of electrical resistance. Read More »

Synopsis: Spin Transport in Room-Temperature Germanium
Magnetism

Synopsis: Spin Transport in Room-Temperature Germanium

Germanium layers can carry spin-polarized currents over several hundred nanometers at room temperature, a key asset for spintronic applications. Read More »

Viewpoint: Crystal Vibrations Invert Quantum Dot Exciton
Semiconductor Physics

Viewpoint: Crystal Vibrations Invert Quantum Dot Exciton

Phonons assist in creating an excitation-dominated state, or population inversion, in a single quantum dot—an effect that could be used to realize single-photon sources. Read More »

More Articles