News

26.02.2024 New Joint Publication in Antiferromagnetic Spintronics

A joint publication with Jairo Sinova, Ricardo Zarzuela and V.K. Bharadwaj about homochiral antiferromagnetic merons, antimerons and bimerons in synthetic antiferromagnets has been published in Nature Communications.

They realize chiral in-plane topological antiferromagnetic spin textures namely merons, antimerons, and bimerons in synthetic antiferromagnets by concurrently engineering the effective perpendicular magnetic anisotropy, the interlayer exchange coupling, and the magnetic compensation ratio. They demonstrate multimodal vector imaging of the three-dimensional Néel order parameter, revealing the topology of those spin textures and a globally well-defined chirality, which is a crucial requirement for controlled current-induced dynamics. Their analysis reveals that the interplay between interlayer exchange and interlayer magnetic dipolar interactions plays a key role to significantly reduce the critical strength of the Dzyaloshinskii-Moriya interaction required to stabilize topological spin textures, such as antiferromagnetic merons, in synthetic antiferromagnets, making them a promising platform for next-generation spintronics applications.

You can find the publication under Nat Commun 15, 1641 (2024).

14.02.2024 New Joint Publication in Altermagnetism

A joint publication with Jairo Sinova and Libor Šmejkal about the altermagnetic lifting of the Kramers spin degeneracy has been published in Nature.

They write that the lifted Kramers spin degeneracy (LKSD) underpins established practical applications as well as current frontier research, ranging from magnetic-memory technology to topological quantum matter. They continue, that LKSD has been considered to originate from two possible internal symmetry-breaking mechanisms. The first refers to time-reversal symmetry breaking by magnetization of ferromagnets and tends to be strong because of the non-relativistic exchange origin. The second applies to crystals with broken inversion symmetry and tends to be comparatively weaker, as it originates from the relativistic spin–orbit coupling (SOC). A recent theory work based on spin-symmetry classification has identified an unconventional magnetic phase, dubbed altermagnetic, that allows for LKSD without net magnetization and inversion-symmetry breaking. Here they provide the confirmation using photoemission spectroscopy and ab initio calculations. They identify two distinct unconventional mechanisms of LKSD generated by the altermagnetic phase of centrosymmetric MnTe with vanishing net magnetization. Their observation of the altermagnetic LKSD can have broad consequences in magnetism. It motivates exploration and exploitation of the unconventional nature of this magnetic phase in an extended family of materials, ranging from insulators and semiconductors to metals and superconductors, that have been either identified recently or perceived for many decades as conventional antiferromagnets.

You can find the publication under Nature 626, 517–522 (2024).

13.02.2024 Upcoming SPICE Young Research Leaders Group Workshop: Correlation and Topology in magnetic materials

The mathematical concept of “topology”, developed in the past century, has become the real game changer in condensed matter physics. The particular coupling of the electronic wavefunctions with the spin configuration define the material topology, from which unique electronic properties arise. Skyrmions, anomalous spin Hall effect or topological superconductivity are some examples of the fascinating phenomena and applications that this new concept enables.
Besides the potential technological transfer, topology also paves the way for quantum states, a phenomenal playground for investigating fundamental interactions of correlated electrons under topological protection. On top of these correlated materials, topological superconductivity, essential to the realization of quantum computing, is one of the most “hot research lines”, expected to generate the biggest revolution in the field.
By gathering young researchers from both topology and correlation topics, we aim to get a broad perspective of one of the hottest topics in condensed matter physics. The workshop will count on researchers from both experimental and theoretical fields, aiming to promote collaborations across different perspectives.

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.

13.02.2024 Upcoming SPICE Workshop on Spin textures: Magnetism meets Plasmonics

Spin textures in solids originate from the complex interaction between electrons and atoms. In particular, the collective behavior of electrons is often key to emergent physical properties. For example, the spins of localized as well as itinerant electrons can interact to realize statically (meta-) stable magnetic spin textures, including spin-spirals, vortices, skyrmions, multi-q structures, i.e., magnetic arrangements characterized by multiple wave vectors in their magnetic order parameter.
Alternatively, electrons can be excited collectively by electromagnetic waves such that the electrons oscillate to realize plasmons. Being highly endowed with tunability, the field of plasmonics, has rapidly emulated several interesting spin structures.
In both fields, skyrmions and topological excitations play a crucial role spurred by the idea of robust states of matter for applications including storage and information technology. While there are a lot of similarities between magnetic and electromagnetic spin textures there are also key differences in their physics. For example, each field has its individual challenges to realize tailored spin textures: While a limitation in magnetism is that certain competing interactions are required to realize spin structures, in plasmonics certain field components are prohibited hindering the formation of arbitrary spin structures. External stimuli are interesting for both research fields to manipulate the unique magnetic and electronic properties of the excitations.
This workshop aims to bring together experts from both magnetism and plasmonics to foster the discovery of new spin textures.

If you are interested in this SPICE-Workshop, please click the button, to apply before May 6th, 2024. If your application is successful, you will be contacted in May 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-School on Quantum Spinoptics

This joint workshop and school aims to bring together students and researchers in the separate fields of solid-state physics and quantum optics, with the goal of fostering an exchange of ideas and knowledge that might spawn a new exciting field of “Quantum Spinoptics.” The common ground for this inter-disciplinary field is the increasingly recognized importance to develop techniques to controllably couple qubits (either atoms or solid-state spins) to interesting quantum “baths” (photons or magnetic materials). Such control is expected to open up diverse scientific and technological opportunities, such as:
- Long-distance coupling and entanglement of qubits through coherent interactions or correlated dissipation
- State protection through correlated dissipation (e.g., subradiance) and associated applications
- Quantum sensing and metrology, and novel probes of condensed matter systems
- Realization of novel classes of out-of-equilibrium dynamics and phases
While these ideas are already starting to be explored separately within solid-state physics and quantum optics, we envision that scientific progress and opportunities will significantly accelerate with the cross-fertilization of ideas. The joint workshop-school format is intended to provide a venue equally devoted to the dissemination of latest research developments, discussion of scientific ideas, and providing a pedagogical background to establish a common “scientific language” for this new field. To that end, the event will feature two extended introductory lectures, featuring scientific and pedagogical leaders within the fields of solid-state physics and quantum optics. We thus especially encourage young scholars to attend and to also contribute in a dedicated poster session.

If you are interested in this SPICE-Workshop, please click the button, to apply before April 1st, 2024. If your application is successful, you will be contacted in April 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 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.

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.

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).