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06/08/2020: Spintronics:
Researchers show how to make non-magnetic materials magnetic

A complex process can modify non-magnetic oxide materials in such a way to make them magnetic. The basis for this new phenomenon is controlled layer-by-layer growth of each material. An international research team with researchers from Martin Luther University Halle-Wittenberg (MLU) reported on their unexpected findings in the journal "Nature Communications".

The theoretical calculations and explanations for this newly discovered phenomenon were made by Ingrid Mertig’s team of physicists. The method was then experimentally tested by several research groups throughout Europe - including a group led by Professor Kathrin Dörr from MLU. They were able to prove the magnetism in the materials. "This combination of computer simulations and experiments enabled us to decipher the complex mechanism responsible for the development of magnetism," explains Mertig.

The study builds upon the work of the former Collaborative Research Centre 762 "Functionality of Oxide Interfaces" at MLU, which was funded by the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) from 2008 to 2019.

04/03/2020: Magnetic whirls in future data storage devices

Magnetic (anti)skyrmions are microscopically small whirls that are found in special classes of magnetic materials. These nano-objects could be used to host digital data by their presence or absence in a sequence along a magnetic stripe. A team of scientists from the Max Planck institutes (MPI) of Microstructure Physics in Halle and for Chemical Physics of Solids in Dresden and the Martin Luther University Halle-Wittenberg (MLU) has now made the observation that skyrmions and antiskyrmions can coexist bringing about the possibility to expand their capabilities in storage devices. The results were published in the scientific journal "Nature Communications".

With the ever-increasing volumes of digital data from the growing numbers of devices, the demand for data storage capacity has been enhanced dramatically over the past few years.  Conventional storage technologies are struggling to keep up. At the same time, the ever-increasing energy consumption of these devices - hard disk drives (HDD) and random-access memories (RAM) - is at odds with a "green" energy landscape. Required are entirely new devices that have greater performance at a drastically reduced energy consumption.

A promising proposal is the magnetic racetrack memory-storage device. It consists of nanoscopic magnetic stripes (the racetracks) in which data is encoded in magnetic nano-objects, typically by their presence or absence at specified positions. One possible nano-object is a magnetic (anti)skyrmion: this is an extremely stable whirl of magnetization with a size that can be varied from micrometers to nanometers. These objects can be written and deleted, read and, most importantly, moved by currents, therefore allowing the racetrack to be operated without any moving parts. "By stacking several racetracks, one on top of each other, to create an innately three-dimensional memory-storage device, the storage capacity can be drastically increased compared to solid state drives and even hard disk drives. Moreover, such a racetrack memory device would operate at a fraction of the energy consumption of conventional storage devices. It would be much faster, and would be much more compact and reliable", explains Prof Stuart Parkin, director of the MPI of Microstructure Physics in Halle and Alexander von Humboldt Professor at the MLU.

"Skyrmions and antiskyrmions are 'opposite’ magnetic whirls. However, until recently, it was believed that these two distinct objects can only exist in different classes of materials." explains Prof Ingrid Mertig from the institute of physics at MLU. The research team from Max Planck institutes in Halle and Dresden and the MLU has now discovered that antiskyrmions and skyrmions can coexist under certain conditions in the same material. Dr Börge Göbel, a member of Mertig’s research group, provided the theoretical explanation for the unexpected experimental observations that were carried out by Jagannath Jena in Parkin’s group. The measured single crystal materials, Heusler compounds, were prepared by Dr Vivek Kumar in the group of Prof Claudia Felser at the MPI in Dresden.

08/10/2019: Patented concept from Halle: novel magnetic tunnel diodes and transistors

Today's computer processors are increasingly pushed to their limits due to their physical properties. Novel materials could be the solution. Physicists from Martin Luther University Halle-Wittenberg (MLU) have investigated if and how these materials might be developed. They have proposed a new device concept that utilises the latest findings from the field of spintronics and filed a patent. The team reported on their research in the journal "ACS Applied Electronic Materials".

With their new concept, the researchers at MLU want to unify memory and logic in a single device, which might render possible an all-in-one chip solution for computing. Common processors use billions of transistors to process data. "The energy efficiency of these individual components determines how much energy is consumed by the processor overall," says Professor Ingrid Mertig, a theoretical physicist at MLU. Energy loss, which occurs when electrical energy is converted into heat, remains the biggest challenge, she explains. When developing these components, scientists also have to decide whether to create very powerful and energy-efficient components that can only be used for a specific purpose, or to create parts that can be used in a variety of ways, but which have a lower performance and require more energy. For its latest innovation, the team of researchers investigated whether spintronics can be used to solve these problems.

"Our proposals for the new diodes and transistors combine data processing and storage. There is no loss of energy to store date and they can be reconfigured," explains Dr Ersoy Şaşıoğlu, a physicist at MLU and first author of the paper. A patent has already been filed for the design of these spintronic components.

09/09/2019: Spintronics: Physicists discover new material for highly efficient data processing

A new material could aid in the development of extremely energy efficient IT applications. The material was discovered by an international research team in cooperation with Martin Luther University Halle-Wittenberg (MLU). The electrons at the oxide interface of the material possess special properties which drastically increase the conversion rate of spin current to charge current. This is the foundation for future spintronic applications. The new material has been found to be more efficient than any previously investigated material, the team writes in the journal "Nature Materials".

Electric current flows through all technical devices. Heat is generated and energy is lost. Spintronics explores new approaches to solving this issue that utilise a special property of electrons: spin. This is a type of intrinsic angular momentum of electrons that generates a magnetic torque and it is what causes magnetism. The idea behind spintronics is: If spin current flows through a material instead of an electrical charge, no heat is generated and significantly less energy is lost in the device. "However, this approach still requires an electric current for the device to work. Therefore, an efficient spin-to-charge conversion is necessary for this novel technology to work," explains Professor Ingrid Mertig, a physicist at MLU. Her research group is part of the international research team that discovered the new material. The work was led by the French physicist Dr Manuel Bibes, who conducts research at the renowned institute Centre national de la recherche scientifique (CNRS) - Thales.

The group investigated the interface between two oxides. "The two substances are actually insulators and are non-conductive. However, a kind of two-dimensional electron gas forms at their interface, which behaves like a metal, conducts current and can convert charge current into spin current with extremely high efficiency," explains Mertig. Dr Annika Johansson and Börge Göbel, two members of her research group, provided the theoretical explanation for this unusual observation. According to the researchers, the new material is significantly more efficient than any other known material. This could pave the way for the development of new, energy-saving computers.

27/04/2018: Halle physicists on the road to success

Successful knowledge transfer requires excellent basic research which is run by the researchers of the Institute of Physics at the university, where not only three Collaborative Research Centres (SFB) of the German Research Foundation and an Alexander von Humboldt Professorship are located. The researchers also have excellent international networks and regularly attract attention with publications in renowned scientific journals.

The Institute of Physics at Martin Luther University, which is comparatively small with 14 professorships, is currently funded by three Collaborative Research Centres of the German Research Foundation. In detail, these are the SFB 762 "Functionality of Oxide Interfaces", which was established in 2008, the Transregio-SFB 102 "Polymers under Constraints" established with the University of Leipzig in 2011, and the Transregio-SFB 227 "Ultrafast Spin Dynamics"   , newly acquired last year together with Freie Universität Berlin. All three initiatives are embedded in the scientific research network "Materials Science - Nanostructured Materials" at the University, which deals with the development of novel materials and innovative measurement methods.

The Institute of Physics at the Martin Luther Unievrsity has also made a name for itself worldwide - both as a venue for international conferences and as an institution for highly respected guest scientists. Together with the Max Planck Institute of Microstructure Physics   , the physicists succeeded in bringing the inventor of modern hard disk technology, Prof. Dr. Stuart Parkin, to Halle in 2013 via an Alexander von Humboldt Professorship - Germany's highest endowed international research prize. The French Physics Nobel Prize winner Prof. Dr. Albert Fert has also been a guest of the institute since 2014. And only a few weeks ago, Dr. Manuel Bibes from the renowned Centre national de la recherche scientifique (CNRS) Thales was awarded the Friedrich Wilhelm Bessel Research Award by the Alexander von Humboldt Foundation to work in Halle for several months.

17/12/2015: Hugo Junkers Award for Nicki Hinsche

Physicist Dr. Nicki Hinsche has been awarded the first prize in the category Basic Sciences of the Hugo Junkers Innovation Award Saxony-Anhalt 2015 for the project "Nanostructured thermoelectric layered systems". "I traveled all the way from Copenhagen for the award", says Dr. Nicki Hinsche, who now works at the Technical University of Denmark. For his project he received the 10,000 euros first prize for the most innovative project in the Basic Sciences category. The researchers, for example, make use of waste heat, which is generated by technical devices but also by living organisms and released into the environment, in order to convert it into electrical energy.

20/11/2015: SFB 762 is funded for another four years

The Senate Committee on Collaborative Research Centres of the German Research Foundation has granted the third funding period of the SFB 762 during its meeting on November 19, 2015. The funding of the SFB for the years 2016-2019 amounts to an annual 2.5 million euros; all 21 proposed projects are funded.

"The DFG reviewers have confirmed that the SFB 762 has developed into an internationally visible centre for oxide interfaces. We are proud!", says Prof. Dr. Ingrid Mertig, the spokesperson of the SFB.

06/03/2015: Nobel Laureate in Physics Albert Fert visits University of Halle

The French Nobel Laureate in Physics Professor Albert Fert visits the Martin-Luther-University Halle-Wittenberg for his first research stay. In a Special Physical Colloquium on the Weinberg Campus he will speak on Thursday, March 12 from 17:15 o'clock publicly about spin-orbitronics, which could lead to a more powerful yet more energy-efficient computer technology. Albert Fert is one of this year's recipients of a Humboldt Research Award of the Alexander von Humboldt Foundation. The prize money he uses, among other things, for several research stays in Halle.

Host for Fert's stay is Prof. Dr. Ingrid Mertig, spokesperson of the Collaborative Research Centre (SFB) 762 "Functionality of Oxide Interfaces", which is part of the research network "Nanostructured Materials", in which besides the University also the Max Planck Institute of Microstructure Physics is involved. In the SFB scientists are investigating oxide nanostructures that have, like spin-orbitronics, the potential for new storage technologies. "We are looking forward to the collaboration with Albert Fert and expect new impulses for our SFB," says Ingrid Mertig.

28.10.2014: Humboldt Research Award for Albert Fert

The selection committee of the Alexander von Humboldt Foundation    decided at its last meeting on October 24, 2014 to give a Humboldt Research Award    to Professor Albert Fert    (France).

Albert Fert, who together with Peter Grünberg was awarded the Nobel Prize in Physics for the discovery of the giant magnetoresistance (GMR) effect in 2007, will use the prize money for research stays in Germany, among others in Halle. In Halle Albert Fert will also work with Stuart Parkin   , whose merit is the technological development for the utilization of the GMR effect in modern storage media.

12.05.2014: Article has been selected as a ‘Highlight of 2013’ of the New Journal of Physics

H. Mirhosseini, M. Flieger, and J. Henk
Dirac-cone-like surface state in W(110): dispersion, spin texture and photoemission from first principles
New J. Phys. 15, 033019 (2013)   

Certificate
NJP-Urkunde.pdf (627.8 KB)  vom 12.05.2014

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