Synopsis: Optimizing Topological Insulators

Tweaking the bulk properties of a topological insulator reveals the behavior of its surface states.
Synopsis figure
Z. Ren et al., Phys. Rev. B (2011)

3D topological insulators comprise a class of materials that have gapless surface states on top of an insulating ground state in the bulk. Any transport measurement of these surface states is influenced by the transport properties of the bulk. We can minimize the contribution of the bulk if we can make it a better insulator. However, none of the commonly known 3D topological insulators is a good insulator.

In a paper in Physical Review B, Zhi Ren and colleagues at Osaka University, Japan, demonstrate a way to make better insulators without destroying the gapless surface states. The authors fabricated single crystals using bismuth (Bi), antimony (Sb), tellurium (Te), and selenium (Se) with variable concentrations of each element. They ensured that the samples preserved the crystal structure of Bi2Te3, a prototypical 3D topological insulator. By changing the amount of each element, they managed to decrease the number of free charge carriers in the bulk, thereby making a better insulator. With this control over the property of the bulk, the authors pinpointed the contribution of the surface states in the transport measurements. The paper further suggests that the use of thinner samples may lead to easier identification of these topological surface states. – Hari Dahal


More Announcements »

Subject Areas

SpintronicsStrongly Correlated Materials

Previous Synopsis

Next Synopsis


Keep Oxygen Out

Read More »

Related Articles

Viewpoint: Orbital Engineering, By Design
Materials Science

Viewpoint: Orbital Engineering, By Design

In transition-metal oxides, the ability to control which atomic orbitals are occupied by electrons could be used to develop materials with new functionalities. Read More »

Synopsis: Controlling Magnetism by Electricity

Synopsis: Controlling Magnetism by Electricity

Small voltages can control the magnetic properties of thin films at room temperature. Read More »

Viewpoint: Spin Transport Goes Ballistic
Semiconductor Physics

Viewpoint: Spin Transport Goes Ballistic

The injection of spins into a high-mobility two-dimensional electron gas is unexpectedly efficient, suggesting that new theories may be needed to describe spin transport in such systems. Read More »

More Articles