Back to Table of contents

Primeur weekly 2016-05-30

Focus

CERN technology for Large Hadron Collider to evolve from computing Grid to scientific Cloud ...

Quantum computing

Purdue professor selected to establish Station Q Purdue, part of Microsoft Station Q ...

Top international award for UNSW Australia quantum computing chief ...

D-Wave Systems to organize Quantum Computing Seminar at ISC16 ...

New device steps toward isolating single electrons for quantum computing ...

Dartmouth team creates new method to control quantum systems ...

Focus on Europe

The Instituto de Astrofísica de Canarias will participate in new European SUNDIAL network ...

Discover how digital technology impacts scientific practice ...

Digital Infrastructures for Research 2016 to issue Call for Papers ...

Middleware

Cray Urika-GX system harnesses supercomputing performance to tackle Big Data analytics ...

Hardware

Cavium announces ThunderX2 ...

Gigantic ultrafast spin currents ...

Introducing the AMD FirePro S7100X, the industry’s first and only hardware-virtualized GPU for blade servers ...

STULZ USA announces strategic investment and commercial partnership with CoolIT Systems ...

Made-in-India supercomputers by August 2017 under govt's Rs 4,500-crore National Supercomputing Mission ...

Applications

KIT brings outstanding experimental physicist back to Germany ...

NOAA's premier forecast model goes 4D ...

Argonne launches first tech incubator ...

Current atmospheric models underestimate the dirtiness of Arctic air ...

The Cloud

FleetCor adopts IBM Cloud to help businesses stay in the fast lane ...

EnerTech of Kuwait Investment Authority selects Cloud-based analytics service from IBM and Waterfund for insights into water costs ...

IBM offers Watson services on Twilio marketplace ...

Gigantic ultrafast spin currents


A laser pulse hits nickel (green). Spin-up-electrons (red) change into silicon (yellow). Electrons with both spin-orientations change back from silicon into nickel. Credit: TU Wien.
24 May 2016 Vienna - Scientists from TU Wien - Vienna - are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics. In our computer chips, information is transported in form of electrical charge. Electrons or other charge carriers have to be moved from one place to another. For years scientists have been working on elements that take advantage of the electrons angular momentum - their spin - rather than their electrical charge. This new approach, called "spintronics" has major advantages compared to common electronics. It can operate with much less energy.

However, it is difficult to create such a spin current, which is required in spintronics. In the journal Physical Review Letters , physicists from TU Wien have now proposed a new method to produce gigantic spin currents in a very small period of time. The secret is using ultra short laser pulses.

For every electron, two different spin-states are possible; they are called "spin up" and "spin down". The electron spin is responsible for ferromagnetism: when many electron spins in a metal are aligned, they can collectively create a magnetic field. Therefore, using ferromagnets to create spin flux seems like a straightforward idea. "There have been attempts to send an electric current through a combination of magnets and semiconductors", stated Professor Karsten Held, TU Wien. "The idea is to create a flux of electrons with uniform spin, which can then be used for spintronic circuits. But the efficiency of this method is very limited."

Karsten Held and Marco Battiato found another way. In computer simulations, they analysed the behaviour of electrons in a thin layer of nickel when it is attached to silicon and hit with ultra short laser pulses. "Such a laser pulse has an overwhelming effect on the electrons in nickel", stated Marco Battiato. They are swept away and accelerated towards the silicon.

An electric field builds up at the interface between nickel and silicon, which stops the current. Electrons still keep on migrating between the nickel layer and silicon, but the motion in both directions cancel each other, there is no net charge transfer.

But even when no electric charge is transported, it is still possible to transport spin. "In the nickel layer, there are both spin-up electrons as well as spin-down electrons", stated Karsten Held. "But the metal atoms influence both kinds of electrons in different ways. The spin-up electrons can move rather freely. The spin-down electrons however have a much higher probability of being scattered at the nickel atoms."

When the electrons are scattered, they change their direction and lose energy. Therefore, the majority of the electrons which do make it all the way to the nickel-silicon interface are spin-up electrons. Electrons which move in the opposite direction have equal probabilities of being in the spin-up or spin-down state.

This spin-selective effect leads to a dominance of spin-up electrons in the silicon. This means that a spin current has been injected into the silicon without creating a charge current. "Our calculations show that this spin-polarization is extremely strong - much stronger than we could create with other methods", stated Marco Battiato. "And this spin flux can be created in femtoseconds." Time is of the essence: today's computer processors operate with gigahertz frequencies. Billions of operations per second are possible. Even higher frequencies in the terahertz range can only be reached with extremely fast elements.

So far, the method has only been tested in computer simulations. But Marco Battiato and Karsten Held are already working with experimentalists who want to measure this laser-triggered spin flux. "Spintronics has the potential to become a key technology of the next few decades", stated Karsten Held. "With our spin injection method there is now finally a way to create ultrafast, extremely strong spin currents."
Source: Vienna University of Technology, TU Vienna

Back to Table of contents

Primeur weekly 2016-05-30

Focus

CERN technology for Large Hadron Collider to evolve from computing Grid to scientific Cloud ...

Quantum computing

Purdue professor selected to establish Station Q Purdue, part of Microsoft Station Q ...

Top international award for UNSW Australia quantum computing chief ...

D-Wave Systems to organize Quantum Computing Seminar at ISC16 ...

New device steps toward isolating single electrons for quantum computing ...

Dartmouth team creates new method to control quantum systems ...

Focus on Europe

The Instituto de Astrofísica de Canarias will participate in new European SUNDIAL network ...

Discover how digital technology impacts scientific practice ...

Digital Infrastructures for Research 2016 to issue Call for Papers ...

Middleware

Cray Urika-GX system harnesses supercomputing performance to tackle Big Data analytics ...

Hardware

Cavium announces ThunderX2 ...

Gigantic ultrafast spin currents ...

Introducing the AMD FirePro S7100X, the industry’s first and only hardware-virtualized GPU for blade servers ...

STULZ USA announces strategic investment and commercial partnership with CoolIT Systems ...

Made-in-India supercomputers by August 2017 under govt's Rs 4,500-crore National Supercomputing Mission ...

Applications

KIT brings outstanding experimental physicist back to Germany ...

NOAA's premier forecast model goes 4D ...

Argonne launches first tech incubator ...

Current atmospheric models underestimate the dirtiness of Arctic air ...

The Cloud

FleetCor adopts IBM Cloud to help businesses stay in the fast lane ...

EnerTech of Kuwait Investment Authority selects Cloud-based analytics service from IBM and Waterfund for insights into water costs ...

IBM offers Watson services on Twilio marketplace ...