News

13.02.2024 Upcoming SPICE Workshop on Quantum Matter for Quantum Technologies

Quantum materials hold the key to unlocking the next frontier of quantum advancements, and at the forefront of this transformation are innovative Josephson junction concepts designed to harness the inherent properties of these quantum materials. This includes pioneering approaches such as integrating Josephson junctions into 2D materials, exploring the intriguing realm of twisted bilayers, devising semiconductor-based superconducting qubits, understanding novel phenomena in chiral and nodal superconductors, just to name a few. Within this diverse landscape, these developments bring forth a wealth of advanced functionalities, including the ability to fine-tune quantum systems through electric gate control, compatibility with magnetic fields, and the exploration of unconventional Josephson potentials.

In this workshop, our vision is to nurture collaborative synergy among diverse scientific communities that have been somewhat disconnected. This collaborative effort aims to foster innovation and deepen our comprehension of various facets leading to novel qubit concepts based on exotic Josephson potentials, novel properties of Josephson quantum matter and the exploration of topological effects. Additionally, we aspire to delve into recent proposals that revolve around unconventional superconductivity. Our shared goal is to establish a new technological paradigm within the realm of quantum technologies, pushing the boundaries of what is currently achievable with standard superconducting circuits and unlocking the full potential of quantum materials and Josephson junctions.

This workshop is organized by SPICE as part of the Gutenberg International Conference Center (GICC) at Johannes Gutenberg University Mainz (JGU). The GICC is funded through the German Research Foundation’s (DFG) university allowance in the Excellence Strategy program and aims at fostering JGU as a national and international research hub. By organizing regular conferences and workshops in fields of excellent JGU research, the GICC provides a platform to build interest networks and collaborations – to promote exchange and dialog among academics and research groups from all over the world.

If you are interested in this SPICE-Workshop, please click the button, to apply before March 11th, 2024. If your application is successful, you will be contacted in March 2024 with a link to register. The conference fee is 450 euros. Accommodation is not included. The online conference fee (live in Zoom participation) is 50 euros. Poster Sessions and Poster Flash Presentations will be organized only for those attending in person.

13.02.2024 Upcoming SPICE Workshop on Nanomagnetism in 3D

The scientific and technological exploration of three-dimensional magnetic nanostructures is an emerging research field with exciting novel physical phenomena, originating from the increased complexity in spin textures, topology, and frustration in three dimensions. Tailored three-dimensional nanomagnetic structures, including in artificial spin ice systems or magnonics will enable novel applications in magnetic sensor and information processing technologies with improved energy efficiency, processing speed, functionalities, and miniaturization of future spintronic devices. Another approach to explore and harness the full three-dimensional space is to use curvature as a design parameter, where the local curvature impacts physical properties across multiple length scales, ranging from the macroscopic to the nanoscale at interfaces and inhomogeneities in materials with structural, chemical, electronic, and magnetic short-range order. In quantum materials, where correlations, entanglement, and topology dominate, the local curvature opens the path to novel phenomena that have recently emerged and could have a dramatic impact on future fundamental and applied studies of materials. Particularly, magnetic systems hosting non-collinear and topological states and 3D magnetic nanostructures strongly benefit from treating curvature as a new design parameter to explore prospective applications in the magnetic field and stress sensing, micro-robotics, and information processing and storage.
Exploring 3d nanomagnetism requires advances in modelling/theory, synthesis/fabrication, and state-of-the-art nanoscale characterization techniques to understand, realize and control the properties, behavior, and functionalities of these novel magnetic nanostructures.
This workshop will bring together experts from different areas in the magnetism community to discuss the challenges and opportunities of expanding nanomagnetism towards the third dimension.

This workshop is organized by SPICE as part of the Gutenberg International Conference Center (GICC) at Johannes Gutenberg University Mainz (JGU). The GICC is funded through the German Research Foundation’s (DFG) university allowance in the Excellence Strategy program and aims at fostering JGU as a national and international research hub. By organizing regular conferences and workshops in fields of excellent JGU research, the GICC provides a platform to build interest networks and collaborations – to promote exchange and dialog among academics and research groups from all over the world.

If you are interested in this SPICE-Workshop, please click the button, to apply before March 4th, 2024. If your application is successful, you will be contacted in March 2024 with a link to register. The conference fee is 450 euros. Accommodation is not included. The online conference fee (live in Zoom participation) is 50 euros. Poster Sessions and Poster Flash Presentations will be organized only for those attending in person.

06.02.2024 "Science" acknowledges our work

We are proud to announce that the remarkable discovery of altermagnetism of our group and especially Libor Šmejkal are presented in an article from Science. The presence of a new magnetic class which might lead to fast eco-friendly electronic devices is reaching further interest in general science. This underlines the impact of our current research and will bring even more interest into the research field.

You can find the article here.

31.01.2024 New Joint Publication in Altermagnetism

A joint publication with Jairo Sinova, Libor Šmejkal and Anna Hellenes about the observation of time-reversal symmetry breaking in the band structure of altermagnetic RuO2 has been published in Science Advances.

They directly observe strong time-reversal symmetry breaking in the band structure of altermagnetic RuO2 by detecting magnetic circular dichroism in angle-resolved photoemission spectra. Their experimental results, supported by ab initio calculations, establish the microscopic electronic structure basis for a family of interesting phenomena and functionalities in fields ranging from topological matter to spintronics, which are based on the unconventional time-reversal symmetry breaking in altermagnets.

You can find the publication under Sci. Adv. 10, eadj4883 (2024).

29.01.2024 New Joint Publication in Altermagnetic Transport

A joint publication with Jairo Sinova and Libor Šmejkal about the crystal thermal transport in altermagnetic
RuO2 has been published in Physical Review Lettters.

They demonstrate the emergence of a pronounced thermal transport in the recently discovered class of magnetic materials—altermagnets. From symmetry arguments and first-principles calculations performed for the showcase altermagnet, RuO2, they uncover that crystal Nernst and crystal thermal Hall effects in this material are very large and strongly anisotropic with respect to the Néel vector. They find the large crystal thermal transport to originate from three sources of Berry’s curvature in momentum space: the Weyl fermions due to crossings between well-separated bands, the strong spin-flip pseudonodal surfaces, and the weak spin-flip ladder transitions, defined by transitions among very weakly spin-split states of similar dispersion crossing the Fermi surface. Moreover, they reveal that the anomalous thermal and electrical transport coefficients in RuO2 are linked by an extended Wiedemann-Franz law in a temperature range much wider than expected for conventional magnets. Their results suggest that altermagnets may assume a leading role in realizing concepts in spin caloritronics not achievable with ferromagnets or antiferromagnets.

You can find the publication under Phys. Rev. Lett. 132, 056701 (2024).

27.01.2024 New Joint Publication in Antiferromagnetic Spintronics

A joint publication with Jairo Sinova, Libor Šmejkal and Helen Gomonay about phase transitions associated with magnetic-field induced topological orbital momenta in a non-collinear antiferromagnet has been published in Nature communications.

They show that in polycrystalline Mn3Zn0.5Ge0.5N with non-collinear antiferromagnetic order, changes in the diagonal and, rather unexpected, off-diagonal components of the resistivity tensor occur at low temperatures indicating subtle transitions between magnetic phases of different symmetry. This is supported by neutron scattering and explained within a phenomenological model which suggests that the phase transitions in magnetic field are associated with field induced topological orbital momenta. The fact that they observe transitions between spin phases in a polycrystal, where effects of crystalline anisotropy are cancelled suggests that they are only controlled by exchange interactions. The observation of an off-diagonal resistivity extends the possibilities for realising antiferromagnetic spintronics with polycrystalline materials.

You can find the publication under Nat. Comm. 15, 822 (2024).

24.01.2024 The Economist acknowledges our work

We are proud to announce that the remarkable discovery of altermagnetism of our group and especially Libor Šmejkal are presented in an article from The Economist. The presence of a new magnetic class which might lead to fast eco-friendly electronic devices is reaching interest outside of science. This underlines the impact of our current research and will bring even more interest into the research field.

You can find the article here.

18.01.2024 New Publication in Altermagnetism

A joint publication with Libor Šmejkal about the broken Kramers degeneracy in altermagnetic MnTe has been published in Physical Review Letters.

By combining high-quality film growth and in situ angle-resolved photoemission spectroscopy, they report the electronic structure of an altermagnetic candidate, αMnTe. Temperature-dependent study reveals the lifting of Kramers degeneracy accompanied by a magnetic phase transition at TN=267Kwith spin splitting of up to 370 meV, providing direct spectroscopic evidence for altermagnetism in MnTe.

You can find the publication under Phys. Rev. Lett. 132, 036702 (2024).

20.12.2023 New Joint Publication in Altermagnetic Magnonics

A joint publication with Jairo Sinova and Libor Šmejkal about crystal magnons in altermagnets has been published in Physical Review Letters.

They theoretically demonstrate a new class of magnons on a prototypical d-wave altermagnet
RuO2 with the compensated antiparallel magnetic order in the ground state. Based on density-functional-theory calculations they observe that the THz-range magnon bands in RuO2 have an alternating chirality splitting, similar to the alternating spin splitting of the electronic bands, and a linear magnon dispersion near the zero wave vector. They also show that, overall, the Landau damping of this metallic altermagnet is suppressed due to the spin-split electronic structure, as compared to an artificial antiferromagnetic phase of the same RuO2 crystal with spin-degenerate electronic bands and chirality-degenerate magnon bands.

You can find the publication under Phys. Rev. Lett. 131, 256703 (2023).

08.12.2023 New Publication in Antiferromagnetic Transport Theory

A joint publication with Libor Šmejkal and Rafeal González-Hernández about the Anomalous Hall Effect in in doped AgCrSe2 has been published in Advanced Science.

They report the observation of a spontaneous AHE in doped AgCrSe2, a layered polar semiconductor with an antiferromagnetic coupling between Cr spins in adjacent layers. The anomalous Hall resistivity is comparable to the largest observed in compensated magnetic systems to date, and is rapidly switched off when the angle of an applied magnetic field is rotated to ≈80° from the crystalline c-axis. The ionic gating experiments show that the anomalous Hall conductivity magnitude can be enhanced by modulating the p-type carrier density. They also present theoretical results that suggest the AHE is driven by Berry curvature due to noncollinear antiferromagnetic correlations among Cr spins, which are consistent with the previously suggested magnetic ordering in AgCrSe2. Their results open the possibility to study the interplay of magnetic and ferroelectric-like responses in this fascinating class of materials.

You can find the publication under Adv. Sci. 2023, 2307306 (2023).