Synopsis

Optimizing Topological Insulators

Physics 4, s147
Tweaking the bulk properties of a topological insulator reveals the behavior of its surface states.
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


Subject Areas

SpintronicsStrongly Correlated Materials

Related Articles

Multiferroics Are a Spintronics Game Changer
Condensed Matter Physics

Multiferroics Are a Spintronics Game Changer

A new experiment shows that spin currents can be controlled electrically in the room temperature multiferroic material BiFeO3. Read More »

Squeezing a Wigner Solid
Strongly Correlated Materials

Squeezing a Wigner Solid

Researchers have made electrons crystallize into an anisotropic structure, which could lead to new insights into quantum many-body systems. Read More »

Two Spins Take the Quantum Bus
Semiconductor Physics

Two Spins Take the Quantum Bus

Coupling between remote spins on a chip via virtual photons exchanged through a superconducting resonator could lead to gate operations between distant spin qubits. Read More »

More Articles