Synopsis: Insulating behavior in topological insulators

A new topological insulator that approaches true insulating behavior in the bulk is synthesized.
Synopsis figure
Credit: Z. Ren et al., Phys. Rev. B (2010)

3D topological insulators represent a unique quantum state for matter that is supposed to show insulating behavior in the bulk and spin-dependent metallic conduction on the surface. In practice, the best-known exemplars of materials that show a topologically protected metallic surface state, such as Bi2Se3 and Bi2Te3, are also conducting in the bulk due to the presence of vacancies. Significant efforts in trying to find a topological insulator that is truly insulating in the bulk have met with little success.

Presenting their results as a Rapid Communication in Physical Review B, Zhi Ren and colleagues from Osaka University, Japan, have synthesized a new topological insulator, Bi2Te2Se, that approaches insulating behavior in the bulk with a high resistivity. Ren et al. demonstrate variable-range hopping that is the hallmark of an insulator in high-quality single crystals of Bi2Te2Se and Shubnikov-de Haas oscillations coming from the 2D surface metallic state. Surface contribution to the total conductance of the crystal at 6% is the largest ever achieved in a topological insulator. From a detailed study of the Hall effect, the authors also determine the transport mechanism in the bulk that reveals an impurity band in the band gap along with hopping conduction of localized electrons. These results pave the way for exploiting the unique surface conduction properties of topological insulators. – Sarma Kancharla


Announcements

More Announcements »

Subject Areas

Semiconductor PhysicsMesoscopics

Previous Synopsis

Particles and Fields

A question of size

Read More »

Next Synopsis

Fluid Dynamics

Learning the ropes

Read More »

Related Articles

Focus: Supersensitive Needle Magnetometer
Magnetism

Focus: Supersensitive Needle Magnetometer

A tiny, needle-shaped ferromagnet could form a magnetic sensor far better than the current best instruments, according to theory.   Read More »

Synopsis: A Single-Level Electron Turnstile
Mesoscopics

Synopsis: A Single-Level Electron Turnstile

A combination of a quantum dot and superconducting leads works as an electron turnstile, letting only one electron pass at a time through a single level in the dot. Read More »

Viewpoint: Kondo Physics in a Quantum Channel
Mesoscopics

Viewpoint: Kondo Physics in a Quantum Channel

Using a scanning gate microscope, researchers have shown that electron waves scattered from a quantum point contact carry the imprint of interactions with localized electron spins. Read More »

More Articles