News

05.06.2020 New PhD positions in SPIN+X and ElastoQmat projects

Open positions for PhD, Master and Bachelor theses and Postdoctoral positions at the Institute of Physics, Solid State Physics:

PhD Positions in Computational Topological Spintronics (SFB SPIN+X)

PhD Position in Topological Strongly Correlated Magnetic Systems (SFB ElastoQmat), Project A09

PhD Position in Topological Strongly Correlated Magnetic Systems (SFB ElastoQmat), Project B05

Our group works on the area of spintronics and nano-electronics. We work as well on other aspects of solid state theory, with a view towards multi-disciplinary approaches. Our group is very dynamic and we try to create an environment with diverse characters and expertise in order to attain a much more powerful approach to the physical challenges that we try to solve.

04.06.2020 New Science Advance publication on the prediction of the Crystal Hall effect.

Libor Smejkal has predicted a new type of phenomena in the family of spontaneous Hall effects connected to a new type of exchange splitting that depends on the momentum of the electron quasiparticle.

Abstract: Electrons, commonly moving along the applied electric field, acquire in certain magnets a dissipationless transverse velocity. This spontaneous Hall effect, found more than a century ago, has been understood in terms of the time-reversal symmetry breaking by the internal spin structure of a ferromagnetic, noncolinear antiferromagnetic, or skyrmionic form. Here, we identify previously overlooked robust Hall effect mechanism arising from collinear antiferromagnetism combined with nonmagnetic atoms at noncentrosymmetric positions. We predict a large magnitude of this crystal Hall effect in a room temperature collinear antiferromagnet RuO2 and catalog, based on symmetry rules, extensive families of material candidates. We show that the crystal Hall effect is accompanied by the possibility to control its sign by the crystal chirality. We illustrate that accounting for the full magnetization density distribution instead of the simplified spin structure sheds new light on symmetry breaking phenomena in magnets and opens an alternative avenue toward low-dissipation nanoelectronics.

https://advances.sciencemag.org/content/6/23/eaaz8809

01.06.2020 – CRC TRR288 Elastoqmat funded by the DFG

The DFG has funded the CRC TRR288 ELASTO-Q-MAT initiative. It involves the JGU (Sinova co-speaker), Goethe University Frankfurt (Roser Valenti as coordinator and speaker), the Karlsruhe Institute of Technology (Joerg Schmalian co-speaker), and the Max Plank Institutes in Mainz and Dresden. This initiative has the goal to understand, advance, and exploit new physical phenomena emerging from a particularly strong coupling between a material's elasticity and its electronic quantum phases. To this end, we will study the effects of elastic tuning and elastic response of various types of electronic order in representative classes of quantum materials that share a high sensitivity to intrinsic strain or externally applied stress fields

https://www.uni-mainz.de/presse/aktuell/11474_DEU_HTML.php

 

Posted on | Posted in Research

16.01.2020 – Joint Publication by Organic Spintronics Team in Physical Review Letters

A joint publication by the Organic Spintronics Team showing how key spintronic properties of organic molecules adsorbed at a solid surface may be precisely tuned by modifying the adsorbate structure has been published in Physical Review Letters.

DNTT-based molecules at Permalloy
Left: Illustration of spin injection from an inorganic solid substrate into an organic adsorbate layer. Center: Sketch of the adsorption geometry. Right: The adsorbates studied.

More precisely, experiments performed by our collaborators at Cambridge University (UK), show a broadening of the electron spin resonance (ESR) linewidth upon spin injection from a permalloy surface into thin films of DNTT-based organic molecules. This broadening depends sensitively on the composition and surface bonding of the adsorbate molecules.

With the support of theoretical calculations performed by collaborators at Mons University (BE), significant differences in, e.g., the spin diffusion lengths of the organic adsorbate layers can be inferred from the measured variations in ESR linewidth.

08.10.2019 – Publication by Organic Spintronics Team published in Phys. Rev. B

A publication by the Organic Spintronics Team (OST) revising the established method for calculation of molecular spin admixture parameters from first-principles electronic structure theory has been published in Physical Review B. Spin states in a semi-conductor or molecule are a mixture of up and down, because of spin-orbit coupling (SOC). Spin admixture is one of the main ways in which SOC influences the spin dynamics in a molecular material.

The revised method for calculating spin admixture improves on a number of approximations made in the previous method, resulting in greater accuracy and transferability. Still, this method relies on efficient, standard electronic structure theory only, making it easy to implement, and suitable for large-scale calculations.

Molecules in which the new spin admixture method has been evaluated. a) Benzene and thiophene, b) biphenyl, and c) M-phthalocyanines, for M = VO, Mn, Co, Cu.

01.10.2019 – Betrand Dupe leaves INSPIRE to join FNRS in Belgium

The group would like to congratulate Bertrand, who will start in October his new position at Chercheur Qualifié at the Fond National de Recherche Scientifique (FNRS) in Belgium. He will be associated with the University of Liège in the Quantum Materials (Q-mat) research unit, which is part of the Complex and Entangled Systems from Atoms to Materials department (CESAM). He will be establishing and building a group focusing on developing computational methods and researching magnetism and metals looking at skyrmion physics, transport and superconductivity.

26.09.2019 – Publication by Organic Spintronics Team accepted by Physical Review B

A publication by the Organic Spintronics Team (OST) revising the established method for calculation of molecular spin admixture parameters from first-principles electronic structure theory has been accepted for publication in Physical Review B. Spin states in a semi-conductor or molecule are a mixture of up and down, because of spin-orbit coupling (SOC). Spin admixture is one of the main ways in which SOC influences the spin dynamics in a molecular material.

The revised method for calculating spin admixture improves on a number of approximations made in the previous method, resulting in greater accuracy and transferability. Still, this method relies on efficient, standard electronic structure theory only, making it easy to implement, and suitable for large-scale calculations.

Molecules in which the new spin admixture method has been evaluated. a) Benzene and thiophene, b) biphenyl, and c) M-phthalocyanines, for M = VO, Mn, Co, Cu.

30.07.2019 – Publication by Organic Spintronics Team published in the Journal of Physical Chemistry C

A publication by the Organic Spintronics Team (OST) has been published in the Journal of Physical Chemistry C.
This paper presents an application of the recently developed technique for predictions of spin-admixture in molecules. As a computationally robust and efficient, "high-throughput" technique, it is used to describe general trends of in the spin admixture of several classes of molecules, from complex single-molecule magnets to organic polymers. The results emphasize the often counterintuitive variations of molecular spin-orbit coupling with molecular chemical composition and structure.