Topological insulators - Page 3

Researchers from the University of Utah developed a new topological insulator made from bismuth metal deposited on silicon. This material may be very suitable for quantum computers and fast spintronic devices.

This new material has the largest energy gap ever predicted. It can also be used alongside silicon so this material may be relatively easy to be used alongside current semiconductor technology.

Professor Laurens Molenkamp from the University of Würzburg has been awarded a Gottfried Wilhelm Leibniz Prize from the German Research Foundation (DFG). This prestigious award comes with a €2.5 million (almost $3.5 million).

Laurens Molenkamp is regarded as one of the fathers of semiconductor spintronics. He was also the first researchers to succeed in the experimental realization of topological insulators.

Researcher from North Carolina State University developed a new material, strontium tin oxide (Sr3SnO) that is a dilute magnetic semiconductors and can be integrated into silicon chips. This means it may be useful for room-temperature Spintronics devices.

The researchers created this material as an epitaxial (single crystal) thin film on a silicon chip. They actually wanted to test whether it is a topological insulator, but surprisingly found out that it has magnetic semiconductor.

The Semiconductor Research Corporation, and the Defense Advanced Research Projects Agency (DARPA) has awarded a $28 million five-year grant to open the Center for Spintronic Materials, Interfaces, and Novel Architectures, or C-SPIN. This is a multi-university and industry research center that aims to develop technologies for spin-based computing and memory systems. C-SPIN's research areas include perpendicular magnetic materials, spin channel materials (including topological insulators, monolayer MoS2 and graphene), spintronic interface engineering, spin devices and interconnects and spintronic circuits and architectures.

University partners include the University of Minnesota-Twin Cities, Carnegie Mellon University, Cornell University, MIT, Johns Hopkins University and the University of California, Riverside. Industry partners include IBM, Applied materials, Intel, Texas Instruments and Micron.

Researchers have discovered a new wide class of topological insulators (materials that are insulators in the bulk but conductors at the surface) that have very promising properties. These new TIs may enable tuning both electronic and spin (that is, magnetic) properties by using different compounds and confirms the possibility to grow topological insulators with deep-laying, self-protecting and, thus, technologically relevant conducting states. This may have applications in spintronics and quantum computation.

Electron spin-splitting effect (Rashba effect) was demonstrated in a semiconductor (Bismuth selenide) that is far larger than has ever been seen before. This could lead the way towards room-temperature spintronic devices. The Rashba effect is the phenomenon of spin splitting with an applied electric field instead of a magnetic field.

The Rashba effect is crucial for spintronic devices: for example when designing spin transistors, electrons of a single spin are injected and then – under an applied electric field – have their spins rotated. Rashba effect in well-established semiconductors (silicon or gallium arsenide for example) is very small - and so electrons have to travel large distances before any spin rotation is noticeable. This requires very pure materials and very low temperatures.

Researchers from Japan have succeeded in directly observing electron spins in a topological insulator (Bi2Te3). Topological insulator is a promising material for Spintronics because its "edge" can serve as a conducting path depending on the spin polarization.

The magnitude of the out-of-plane spin polarization is 25% at most compared to the in-plane counterpart. The researchers say that the out-of-plane spin polarization exists because of the hexagonally deformed Fermi surface in the Bi2Te3, because it does not exist in TlBiSe2 which has a circular Fermi surface.

Teams from the Johannes Gutenberg University Mainz (JGU) in Germany and Stanford University have uncovered a new quantum state of matter in Heusler compounds which they claim opens up 'previously unimagined usage possibilities'. The scientist from Mainz has shown that many Heusler compounds can behave like topological insulators (TI).

TIs have been studied in the field of solid state and material physics. Characteristic of topological insulators is the fact that the materials are actually insulators or semiconductors, although their surfaces or interfaces are made from metal - but not ordinary metal. Like superconductors, the electrons on the surfaces or interfaces do not interact with their environment - they are in a new quantum state. In contrast with superconductors, topological insulators have two non-interacting currents, one for each spin direction. These two spin currents, which are not affected by defects or impurities in the material, can be employed in the futuristic electronics field of 'spintronics' and for processing information in quantum computers.