Nav: Home

Spin current on topological insulator detected electrically at room temperature

December 07, 2015

Researchers at Chalmers University of Technology have for the first time reported the electrical detection of spin current on topological insulator surfaces at room temperature by employing a ferromagnetic detector. The findings have been published in the journal Nano Letters.

Solid-state materials were conventionally divided into three different classes such as conductors, semiconductors and insulators. Recently, a new class of materials has been proposed and realized, called "topological insulators", where both the insulating and conducting properties can co-exist in the same material.

Topological insulators are insulators inside the bulk, but are conducting on their surfaces with less resistance than the conventional materials. This is possible due to their uniquely strong interaction between electrons' spin and orbital angular momentum with their time reversal symmetry. The interaction is so strong that the spin angular momentum of the electrons is locked perpendicular to their momentum, and generates a spontaneous spin polarized current on the surfaces of topological insulators by applying an electric field.

These spin polarized conducting electrons on the surface have no mass and are extremely robust against most perturbations from defects or impurities, and can enable the propagation of dissipationless spin currents.

The researchers from Chalmers detected the surface spin current electrically on a topological insulator called bismuth selenide (Bi2Se3) for the first time at room temperature employing ferromagnetic tunnel contacts. Such contacts are known to be very sensitive to spin polarization and probe the Bi2Se3 surface by measuring the magnetoresistance due to parallel and anti-parallel alignment of the spin current and the ferromagnet magnetization direction.

"The key factors for these room temperature results are good quality topological insulator crystals and spin sensitive ferromagnetic tunnel contacts carefully prepared by clean room nanofabrication", explains Dr. André Dankert, the lead author of the paper.

Earlier reports in this research field were limited only to measurements at cryogenic temperatures. From the results on the magnitude of the spin signal, its sign, and control experiments, using different measurement configurations, angles and interface conditions, the author's rule out other known physical effects.

"Our results show the electrical accessibility of spin currents on topological insulator surfaces up to room temperature and pave the way for further developments, which can be useful for spin based information processing in the future", says associate professor Saroj Dash, who leads the research group.

However, Saroj Dash cautions that the research on development of these new class materials and measurement techniques are still in its early stage and more experiments are required for further understanding.
Read the article "Room Temperature Electrical Detection of Spin Polarized Currents in Topological Insulators":

Chalmers University of Technology

Related Topological Insulators Articles:

Spinning electrons open the door to future hybrid electronics
A discovery of how to control and transfer spinning electrons paves the way for novel hybrid devices that could outperform existing semiconductor electronics.
New method could enable more stable and scalable quantum computing, Penn physicists report
Researchers from the University of Pennsylvania, in collaboration with Johns Hopkins University and Goucher College, have discovered a new topological material which may enable fault-tolerant quantum computing.
Research accelerates quest for quicker, longer-lasting electronics
In the world of electronics, where the quest is always for smaller and faster units with infinite battery life, topological insulators (TI) have tantalizing potential.
Observation of the phase transition of liquid crystal defects for the first time
KAIST researchers observed the phase transition of topological defects formed by liquid crystal (LC) materials for the first time.
Measured for the first time: Direction of light waves changed by quantum effect
Certain materials can be used to rotate the direction in which the light is oscillating.
Group works toward devising topological superconductor
A team led by Cornell physics associate professor Eun-Ah Kim has proposed a topological superconductor made from an ultrathin transition metal dichalcogenide that is a step toward quantum computing.
Artificial topological matter opens new research directions
An international team of researchers have created a new structure that allows the tuning of topological properties in such a way as to turn on or off these unique behaviors.
Gray tin exhibits novel topological electronic properties in 3-D
In a surprising new discovery, alpha-tin, commonly called gray tin, exhibits a novel electronic phase when its crystal structure is strained, putting it in a rare new class of 3-D materials called topological Dirac semimetals (TDSs).
Chinese scientists discovered tip induced unconventional superconductivity on Weyl semimetals
By using hard point contact measurement on Weyl semimetal TaAs single crystal, Chinese scientists discovered tip induced unconventional superconductivity around contact region on TaAs, which may have nontrivial topology.
The discovery of Majorana fermion
Majorana fermion can serve as the building block of fault tolerant topological quantum computing.

Related Topological Insulators Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Jumpstarting Creativity
Our greatest breakthroughs and triumphs have one thing in common: creativity. But how do you ignite it? And how do you rekindle it? This hour, TED speakers explore ideas on jumpstarting creativity. Guests include economist Tim Harford, producer Helen Marriage, artificial intelligence researcher Steve Engels, and behavioral scientist Marily Oppezzo.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".