Researchers demonstrate and explain surface conduction in a topological insulator

Jul 12, 2012

( -- Researchers at the University of Maryland and the NIST Center for Nanoscale Science and Technology have for the first time experimentally demonstrated surface-only charge conduction in a topological insulator [1], and have theoretically explained the conduction using techniques previously applied successfully to the understanding of graphene [2].

The research team found that the thin Bi2Se3 crystals studied have unusual magneto- that should allow such topological insulators to be used in new types of devices, including high-performance transistors, , and optical detectors.

A topological insulator is an unusual type of three-dimensional material theoretically predicted to carry electric charge only on a two-dimensional boundary.

As recently verified by experiment, topological insulators behave as an in their interior but conduct electrons on their surface.

Topological insulators have also been predicted to have an unusual Dirac-type electronic band structure (shared by graphene), where the electron energy has a linear dependence on momentum, as seen in photons.

By directly measuring the on the surface of thin Bi2Se3 crystals, the researchers showed that the behavior at the surface is consistent with a Dirac band in which the electrons are weakly interacting and disordered.

These features of the Dirac band imply that, unlike , the conducting electrons at the surface of topological insulators have a unique coupling between their spins and charges.

This coupling could give rise to new kinds of solid state devices, including smaller magnetic components whose logic can be switched using nanoscale spin currents.

Explore further: A nanosized hydrogen generator

More information: 1. Surface conduction of topological Dirac electrons in bulk insulating Bi2Se3, D. Kim, S. Cho, N. P. Butch, P. Syers, K. Kirshenbaum, S. Adam, J. Paglione, and M. S. Fuhrer, Nature Physics 8, 460-464 (2012).

2. Two-dimensional transport and screening in topological insulator surface states, S. Adam, E. H. Hwang, and S. Das Sarma, Physical Review B 85, 235413 (2012).

add to favorites email to friend print save as pdf

Related Stories

Unfazed by imperfections

Jul 08, 2011

While insulating against electrical currents in their interior, the surface of materials called topological insulators permits the flow of electron spins relatively unhindered. The almost lossless flow ...

Topological insulators take two steps forward

Aug 10, 2010

A team of researchers from the Stanford Institute of Materials and Energy Science, a joint institute of the Department of Energy's SLAC National Accelerator Laboratory and Stanford University, and their international ...

Topological matter in optical lattices

Nov 28, 2011

Atoms trapped by laser light have become excellent platforms for simulating solid state systems. These systems are also a playground for exploring quantum matter and even uncovering new phenomena not yet seen ...

Physicist wins Packard Fellowship

Oct 16, 2009

( -- MIT physicist Pablo Jarillo-Herrero has won a 2009 David and Lucile Packard Fellowship, an award he will use to study a new class of materials that could have applications in the semiconductor ...

Recommended for you

A nanosized hydrogen generator

Sep 20, 2014

( —Researchers at the US Department of Energy's (DOE) Argonne National Laboratory have created a small scale "hydrogen generator" that uses light and a two-dimensional graphene platform to boost ...

For electronics beyond silicon, a new contender emerges

Sep 16, 2014

Silicon has few serious competitors as the material of choice in the electronics industry. Yet transistors, the switchable valves that control the flow of electrons in a circuit, cannot simply keep shrinking ...

Making quantum dots glow brighter

Sep 16, 2014

Researchers from the University of Alabama in Huntsville and the University of Oklahoma have found a new way to control the properties of quantum dots, those tiny chunks of semiconductor material that glow ...

The future face of molecular electronics

Sep 16, 2014

The emerging field of molecular electronics could take our definition of portable to the next level, enabling the construction of tiny circuits from molecular components. In these highly efficient devices, ...

User comments : 0