Events and News

01.2019
New Funding for Research Exchanges
We are pleased to announce that we have received new funding from the DAAD to support research exchanges for 2020 and 2021. For further details, please contact Prof. Kläui or the scientific coordinator (see Management section).

01-02.03.2019
Research Exchange Meeting at Tohoku University
An exciting research exchange meeting was held at Tohoku University for the latest topics of Spintronics, with participants from the Universities of Lorraine, Mainz and Tohoku. Following the end of the most recent funding period of MaHoJeRo in 2018, this workshop was an ideal platform to share the latest results originating from that project as well as to discuss future collaboration directions and opportunities.

Conventional devices using current CMOS based technologies have the unwelcome side effects of getting too hot and being limited in their speed, operating at GHz frequencies. Eventually, this is slowing down the progress of information technology. In the last years, the emerging field of “magnon spintronics” aimed at using insulating magnets capable of carrying magnetic waves, known as magnons, to solve these problems. Magnons are able to carry information at increased speeds without the production of excess heat. However, experimental observations had so far been limited to ferromagnetic materials. We have demonstrated that magnons can also efficiently carry spin information in antiferromagnets, the largest group of magnetic materials. This class of material has several crucial advantages over ferromagnetic components as they are stable and unaffected by external magnetic fields, a key requirement for future data storage. Additionally, antiferromagnet based devices can be potentially operated thousands of times faster than current technologies, as their intrinsic dynamics are in the THz range. As a result, antiferromagnetic magnons could thus be used in future ultra-fast and low power technological devices.

An electrical current in a platinum wire (left) creates a magnetic wave in the antiferromagnetic iron oxide (red and blue waves). This is measured as a voltage in a second platinum wire (right). The red and blue arrows represent the antiferromagnetic order of the iron oxide (© Joel Cramer)

More information can be found at: https://www.nature.com/articles/s41586-018-0490-7
And here:
Press Release (english)
Press Release (german)

German newspaper article:
Link to article

A report on the work was shown on TV:
Link to Video

It is our pleasure to welcome Korean partners Prof. Sug-Bong Choe and Myung-Hwa Jung to Mainz for one month research visits. During their stay we have a number of seminars planned to share information and expertise between out institutions, such as the measurement of DMI based on domain wall motion and the properties of topological insulators. Furthermore, several exciting scientific projects are lined up based on the complementary expertise and facilities of the different groups.

Partners at Tohoku University have a new publication in Physical Review Letters on the transport properties associated with Skyrmionic spin-textures in antiferromagnetic materials. The theory work demonstrates that the particular non-trivial magnetic texture of such antiferromagnetic skyrmions promotes a nonvanishing topological spin-Hall effect on the electrons, which also leads to an improvement of the mobility of the Skyrmions. The effect can be tailored with the skyrmion size and the strength of the disorder, opening promising avenues for engineering the effect for future applications. More information can be found here.

In two recent research highlights, we have investigated the spin transport and spin Hall magnetoresistance (SMR) of antiferromagnetic NiO(001) based systems. The projects are collaborations with the group of Prof. Saitoh at Tohoku University and include experimental work in the group of Prof. Mathias Kläui and theoretical work from the group of Prof. Jairo Sinova, both from Mainz. The results reveal that the growth conditions are vital for the spin transport in NiO, even for fully epitaxial systems. Furthermore it is shown that it is possible to electrically detect the Neel vector direction in the system which is particularly exciting for future spintronics applications based on antiferromagnetic materials. The work is published in Physical Review B, including as an editor's suggestion, and can be found via the following links: Spin Transport and SMR.

In a large collaboration including researchers from Mainz and Tohoku, scientists have used terahertz spectroscopy to reveal the initial stages of the spin Seebeck effect with exceptionally fast sub 30 fs temporal resolution. The results reveal that the spin Seebeck effect generates a spin current on the same 100 fs time scale on which the metal electrons thermalize. This observation shows that efficient spin transfer critically relies on carrier multiplication and is driven by conduction electrons scattering off the metal-insulator interface. More information is available in the publication here.

A number of researchers from Mainz have visited Seoul National University for in-depth research discussions and to push-forward joint projects. During the trip, the visitors were able to discuss recent exciting results on Long Distance Lateral Spin Transport in Antiferromagnetic Insulators (arXiv:1805.02451) and Negative Anisotropic Magnetoresistance by Interfacial Spin-Orbit Coupling, as well as discuss new avenues for joint research.

28.05.2018

Publication Highlight in Nature Materials

Researchers at Tohoku and Mainz have made a significant breakthrough in the search for new ways to control spin currents for potential device applications. They developed special tri-layer structures consisting of an antiferromagnetic chromium oxide layer between a ferrimagnetic insulating yttrium iron garnate layer and a heavy platinum layer. The spin current transmission across the structure was investigated as a function of the magnetic field and temperature. Strong changes in the transmission were observed on crossing the Neel temperature of the antiferromagnet or on applying a magnetic field. Effects up to 500% were observed near room temperature, demonstrating the action of a spin-current switch. The work is published in Nature Materials. More information can be found here.

14.03.2018
Publication Highlight in Nature Communications

The implementation of logic operations and thus information processing by means of spin wave (magnon) spin currents is a fundamental goal of the emerging research field of magnon spintronics. In contrast to electrical currents, on which today's information technology is based, magnon spin currents do not conduct electrical charges but rather magnetic momenta. So far, expeerimental demonstrations of magnon logic - e.g. a magnon transistor or a majority gate - were based on either the manipulation or superposition of spin waves during the propagation phase. In a collaboration including MaHoJeRo partners from the groups of Prof. Mathias Kläui in Mainz and Prof. Eiji Saitoh from Tohoku University in Sendai, Japan, we are now able to add a further element to the construction set of magnon logic, directly at the detection site of magnon spin currents. In a ferroic spin valve structure including insulating as well as metallic ferromagnets and antiferromagnets it was possible to demonstrate a magnon detection efficiency which depends on the magnetic configuration of the spin valve. In that manner, the suppression or transmission of the incoming magnon signal can be controlled.

More detailed information can be found in the publication in Nature communications accessible at doi:10.1038/s41467-018-03485-5
and see also the press coverage:
Magnon transistors could give spintronics a boost
Focus: A Trio of Magnon Transistors
JGU press release

14.03.2018
Spin Seebeck induced Spin Transport across an Antiferromagnet

An international team, including researchers from Mainz and Tohoku, have investigated spin transport across antiferromagnets induced by the spin Seebeck effect. In the work the magnonic spin currents are theoretically studied using atomistic spin dynamics simulations. The results are compared to experimental measurements in the yttrium iron garnate / iridium magnanese / platinum system, revealing new insights into the spin transport in these types of system. The results are published in Journal of Physics D: Applied Physics.

10-14.01.2018
New Excitations in Spintronics

A very successful workshop was held in Sendai on "New Excitations in Spintronics", with participants from Tohoku University and Johannes Gutenberg University Mainz. Four researchers from Mainz were able to attend and share exciting new results on "Spin transport in insulator spintronics systems", "Writing and Reading antiferromagnetic Mn2Au: Neel spin-orbit torques and large AMR", "Transport properties of antiferromagnetic Dirac quasi-particles" and "Skyrmion diffusion in Ta-based material with perpendicular magnetic anisotropy". Furthermore productive discussions on future research were held.

31.01.2018
Felix Fuhrmann awarded best bachelor thesis for his work done at Tohoku University

Congratulations to Felix Fuhrmann from Mainz, who has been awarded the best-bachelor thesis for his work carried out during his MaHoJeRo funded research stay at Tohoku university. The thesis, entitled "Magnetothermal and spin transport effects in magnetic multilayers", investigates magnon transport in the yttrium iron garnet (YIG) / cobalt oxide / cobalt system. In the work, spin currents are generated from the YIG layer by spin-pumping which are then transmitted through the structure and detected. The transmitted signal is found to depend sensitively on the alignment of the magnetic layers, showing a magnon spin valve behaviour. The work is currently under review at Nature Communications. A preprint can be found on arXiv:1706.07592 .

31.10.2017 - 02.11.2017
Joint Mainz-Tohoku Student Workshop held in Sendai

11.07.2017
Skyrmion stability revealed by innovative multiscale simulation approach

MaHoJeRo researchers from the universities of both Tohoku and Mainz have investigated the stability of skyrmion spin textures using an innovative modelling approach. Skyrmions are particularly stable topological spin structures with potential applications in devices such as racetrack-style magnetic memories. However in contrast to naive expectations, they do not have an infinite topological protection but rather there are certain energy barriers that exist for their annihilation. The present work investigates the skyrmion stability using the previously developed multiscale simulation approach. In particular the authors are able to demonstrate a scheme to delete skyrmions, which is a key stage of device operation, by using tailored pulses of spin-polarized current. The research is published in Physical Review B.

11.07.2017 - 26.06.2017
Prof. E. Saitoh on sabbatical in Mainz

08.05.2017
New Research from MaHoJeRo Collaboration

MaHoJeRo researchers from both Mainz and Tohoku are part of new work on the dynamics of spin textures in ferromagnetic and antiferromagentic wires. Antiferromagnetic spintronics is in particular becoming a very exciting field at the moment with antiferromagnets displaying a large number of very attractive attributes with respect to device applications such as magnetic memories based on magnetic domain wall motion. The here developed formalism allows one to solve various problems of both ferromagnetic and antiferromagnetic domain wall dynamics and extend it to different geometries. The research is published in Physical Review B.

03.04.2017
New Insights into Spin Hall Magnetoresistance

An international team of researchers, including MaHoJeRo partners from Mainz and Tohoku Universities, have gained new insights into the phenomenon of spin-Hall magnetoreistance (SMR) in systems consisting of heavy-metal, antiferromagnet and magnetic insulator trilayers. SMR is a recently discovered addition to the broad family of magnetoresistance effects which are instrumental in applications for sensing magnetic fields and as a means to electrically read-out the magnetic state of a system. When a current flows through a heavy metal like Pt it generates a spin current via the spin Hall effect. In SMR, the absorption/reflection of this spin current is different depending on the magnetic state of the overlayer, leading to a measurable difference in the effective resistance of the system. The present work helps to explain new features of the effect seen for systems containing antiferromagnetic NiO layers via a systematic temperature and thickness dependent study. The research is published in Physical Review Letters.

01.01.2017
Publication Highlight in Nature Physics including MaHoJeRo partners

One step ahead towards new magnetic storage devices : Fundamental research in the field of magnetic skyrmions proves suitability of thin film systems for applications and presents a new aspect of skyrmion dynamics.

The concept of a magnetic Racetrack Memory, originally proposed by Stuart Parkin (IBM/Halle) in 2008, is one of the current design ideas for future data storage devices. The conceptual device consists of a magnetic stripe, the racetrack, on which the magnetic bits are moved by current due to spin torque effects. No moving parts are required allowing for high speed and low power operation. Using magnetic skyrmions as information carriers might turn out to be a significant improvement, which could increase the data stability and reliability of the devices. The international collaboration which includes MaHoJeRo researchers from both Mainz and Tohoku has demonstrated a billion fold reproducible and fast skyrmion displacement due to current pulses, which is a key requirement for any application. Furthermore, the investigated dynamics turned out to be more complex than originally expected, highlighting that current theoretical descriptions are not sufficient to explain the skyrmion motion.

Details can be found here and in the publication in Nature Physics DOI:10.1038/nphys4000.

14.11.2016
Joint Publication in PRB on a New Approach to Simulating Magnetic Nanostructures

A collaborative work involving SpinNet researchers from Mainz and Germany have today published a new approach to simulate the dynamic properties of spin structures that vary on small length scales. Micromagnetic simulations are an invaluable tool for spintronics researchers to understand the important dynamic behaviour of magnetic systems, such as magnetic switching mechanisms and the propagation of small magnetic textures including domain walls and skyrmions. However while real physical systems are based on discrete atoms, simulating such a discrete lattice for the large structures typically studied takes significant computational power and is prohibitively time consuming. As such, the micromagnetic model is often implemented where the magnetization is treated as a continuous quantity. Yet the reliability of such an approach drastically decreases for certain interesting spin structures exhibiting large gradients of the magnetization. In order to marry the advantages of these two approaches, the researchers have developed a multiscale model approach for their simulations where the software can be adapted to the particular spin structure present, using an atomistic Heisenberg model to describe finescale regions of the structure and a micromagnetic model for the larger regions where the magnetization changes more gradually. The research is published in Physical Review B.

04.02.2016
Joint Publication in Nature Communications: New findings on magnetic spin waves

An international team of researchers involving SpinNet researchers of Johannes Gutenberg University Mainz (JGU) and Tohoku University in Japan gained new insights into magnetic spin waves. Spin waves can evolve in electrically non-conducting materials given a specific temperature gradient and then be converted into electrical energy in an adjacent metallic layer. Thus, thermal energy can be converted into electrical energy. This recently discovered principle allows to think of new ways to recover waste heat and can improve a great variety of processes to be more energy-efficient and environmentally sustainable.

The resulting research paper was published in Nature Communications.

A press relase can be found here.

16.11.2015 - 20.11.2015
Spintronics with Antiferromagnets Workshop & International Workshop Spintronics

Spintronics with Antiferromagnets

Antiferromagnets are spin-symmetry broken ground states that, in contrast to ferromagnets, lack a macroscopic magnetization since the dipolar fields of their staggered spin configurations average to zero. Antiferromagnets are technologically important for exchange-biasing ferromagnets, but only recently they have been recognized to be interesting materials to design active components in spintronic devices such as spin-wave logic gates. For example, antiferromagnets have no cross-talk stray fields, in antiferromagnetic semiconductors the carrier concentration can be controlled, antiferromagnetic domain walls can be engineered, the anisotropic tunneling magnetoresistance (AMR) is substantial, and the antiferromagnetic order parameter can be switched by spin-transfer torques and ultra-fast by lasers.

This workshop will bring together experts in this emerging field. It will cover all aspects of the spintronics with antiferromagnets, including theory, computational material science, and experiments.

Details can be found here

International Workshop : Spintronics

This workshop will cover a wide range of recent progress in spintronics, from fundamental physics to devices for applications. Top researchers from all over the world are invited to present a comprehensive overview of what is happening in this field.

Details can be found here

23.10.2015 - 24.10.2015
Spin Orbit Coupling and Spin Mechanics Workshop

The 29th REIMEI and ERATO-SQR workshop focused on effects of the spin-orbit interaction and the coupling of the spin and lattice degrees of freedom in magnetic nanostructures.

The spin Hall effect has moved into the mainstream of magnetism by generating so-called spin-orbit torques on proximity magnets and being an efficient spin current detector. The electrical and thermal actuation of the magnetization of insulators with extremely high quality factors of the magnetization dynamics has focused attention on the bosonic degrees of freedom in spintronics and the importance of the spin-lattice and spin-rotation couplings.

See here for more details

14.09.2015
Talk Prof. Masahiro Yamashita

11.09.2015 - 12.09.2015
"Spins, Waves and Interactions" Workshop

Many interesting and exciting topics throughout solid state physics with a special focus on magnetism. In addition to the talks and the poster session, the seminar will leave plenty of time for discussions and networking.
More details can be found here.

09.09.2015
Mini-Symposium on Spintronics

Prof. Landau: A Mini-Course on Computer Simulation Methods in Condensed Matter Physics

09.09.2015 09:15 st

MAINZ Seminar Room, Staudinger Weg 9, Room 03-122

See here for more details

Prof. Mizukami: Tetragonal Mn-based Heusler for ultra-high frequency spintronics

09.09.2015 10:30 st

Media Room, Staudinger Weg 7, Room 03-431

See here for more details

Prof. Bauer: New insights in heterostructures with magnetic ions

09.09.2015 11:15 st

Media Room, Staudinger Weg 7, Room 03-431

See here for more details

28.06.2015 - 21.07.2015
Teaching Visit & Talk: Prof. Oleg Tretiakov at JGU Mainz

22.06.2015 - 26.06.2015
Spin Mechanics 3 Workshop

04.03.2015
Talk Prof. Dr. Hermann Dürr

Imaging the ultrafast spin-lattice motion during all-
optical switching of ferromagnets

04.03.2015 09:00 ct

MAINZ Seminar Room, Staudinger Weg 9, Room 03-122

See here for more details

21.02.2015
Prof. Mizukami (Tohoku University) joined SpinNet

SpinNet has a new principal researcher: Prof. Dr. Shigemi Mizukami from the WPI Advanced Institute for Materials Research (Tohoku University). His current research involves New spintronics materials, magnetic tunnel junction and spintronics devices, ultrafast spin dynamics and organic-magnetic metals hybrid structures and devices. He agreed to join SpinNet and announced that "I'm very happy to join this network" during a first meeting at Tohoku University. For more inforamtion about Prof. Mizukami please visit his homepage.

17.02.2015
Agreement on jointly supervised PhD Students between Tohoku University and Johannes Gutenberg University signed

Prof. G. Krausch, president of Johannes Gutenberg University, visited Tohoku University to sign an agreement about jointly supervised PhD student. The agreement is to help students obtain a jointly supervised Ph.D. degree from Tohoku University and University of Mainz in the area of Natural Sciences and Engineering. Both universities expressed their will to extend their collaboration in the field of natural sciences and engineering, an agreement on a double degree master program is currently under negotiation.

18.02.2015 - 20.02.2015
QSNS International Symposium on Quantum System and Nuclear Spin Related Phenomena

The International Symposium on Quantum System and Nuclear Spin Related Phenomena will take place at he Miyagi-Zao Royal Hotel, Miyagi, Japan. The scope of this symposium is:

• Quantum transport in low-dimensional system
• Integer and fractional quantum Hall effectsManipulation of nuclear spins in semiconductor quantum systems
• Highly-sensitive NMR measurements of semiconductor quantum systems
• Electron-spin/nuclear-spin interactions
• Nanoprobe characterization and local nuclear resonance

Interested students are welcome to apply by contacting the SpinNet office.

More details about the sympsium can be found here.

06.09.2014 - 27.09.2014
Teaching Visit: Prof. Oleg Tretiakov at JGU Mainz

24.08.2014 - 29.08.2014
Summer Workshop "Charge and Spin Transport in Non-Metallic Systems and Confined Geometries "

21.06.2014 - 24.06.2014
Spin Mechanics 2 Workshop

14.05.2014
Talk Prof. Dr. Yoshiro Hirayama

Hyperfine Interaction in Semiconductor Quantum Systems

14.05.2014 14:00 st

Lorentz-Room (05-127)

See here for more details

09.10.2013 - 10.10.2013
Workshop on Spin caloritronics in insulators

06.09.2013
Minisymposium on Spintronics
10:30 s.t. Prof. G. Bauer (Tohoku Univ.): Spintronics and spin caloritronics with magnetic insulators

14:00 s.t. Prof. O. Tretiakov (Tohoku Univ.): Topologically Protected Domain-Wall Dynamics in Ferromagnets and Antiferromagnets

Medien-Raum (Room 03-431)

Institute of Physics

Staudingerweg 7

see here for more details

05.09.2013 - 20.09.2013
Teaching Visit: Prof. Gerrit Bauer at JGU Mainz

25.08.2013 - 14.09.2013
Teaching Visit: Prof. Oleg Tretiakov at JGU Mainz

03.06.2013
Honorary Doctorate for SpinNet Researcher Stuart Parkin

05.04.2013 - 09.04.2013
Newspin3 Summer Workshop

...

02.04.2013 - 05.04.2013
Newspin3 Conference in Mainz (Germany)

...

02.04.2013
SpinNet Kick-Off

The SpinNet partners gatherd in Mainz (Germany) for the kick-off meeting to discuss the implementation and measures planned for the upcoming 4 years. The partners will meet at least once annually to discuss progress and future planning of the network.

28.01.2013
SpinNet succesful in aqcuiring funding through DAAD/BMBF