Synopsis: Hall Effect in Quasi-1D Conductors

Experiments have uncovered a new form of Hall effect in organic conductors that confine current flow mostly along one-dimensional molecular strands.
Synopsis figure
K. Kobayashi et al., Phys. Rev. Lett. (2014)

Quasi-1D organic conductors are made up of an array of long molecular strands that confine the flow of electrons to essentially one dimension. This reduced dimensionality results in unique behaviors, such as angle-dependent magnetoresistance. New experiments with a particular quasi-1D organic conductor have revealed an unexpected Hall effect. As reported in Physical Review Letters, the characteristic Hall resistance oscillates as the orientation of the magnetic field is rotated with respect to the conductor’s lattice structure.

The Hall effect occurs when a magnetic field is applied perpendicular to the current flowing in a material. The magnetic force causes charge carriers to accumulate on the sides of the material, resulting in a transverse voltage. If the charge carriers are confined to two dimensions, the Hall effect becomes quantized, in that the Hall resistance (the ratio of transverse voltage to longitudinal current) takes on discrete values.

One would not expect a Hall effect in a truly one-dimensional conductor. However, Kaya Kobayashi of Aoyama Gakuin University in Kanagawa, Japan, and collaborators have discovered a Hall-like response in the quasi-1D organic conductor (TMTSF)2ClO4. They placed single crystals of this conductor in a 15-tesla magnet and measured the transverse voltage as current flowed along the molecular strands. When the team varied the angle between the magnetic field and the crystal lattice, the Hall resistance oscillated from positive to negative values, crossing zero at so-called “magic angles.” These angles correspond to lattice planes that connect a molecular strand to its nearby neighbors. To explain this novel Hall effect, the researchers assume the magnetic field excites an orbital resonance that allows electrons to skip between different strands. – Michael Schirber


Announcements

More Announcements »

Subject Areas

MagnetismMaterials Science

Previous Synopsis

Industrial Physics

Tuning Ductility

Read More »

Next Synopsis

Atomic and Molecular Physics

Giving Weight to Antimatter

Read More »

Related Articles

Focus: Why Some Gels Shrink under Stress
Mechanics

Focus: Why Some Gels Shrink under Stress

The gel material that helps blood clot in a wound has anomalous material properties because of the interaction between the gel's fluid and its microscopic fiber network, according to experiments. Read More »

Synopsis: A New Way to Make Graphene
Graphene

Synopsis: A New Way to Make Graphene

The addition of a rapid-cooling step to the epitaxial growth of graphene on silicon carbide can yield higher-quality graphene sheets. Read More »

Viewpoint: Relaxons Heat Up Thermal Transport
Materials Science

Viewpoint: Relaxons Heat Up Thermal Transport

A recasting of the theory that underlies thermal transport in electrical insulators relies on new vibrational modes called relaxons. Read More »

More Articles