News

25.04.2024 "Science News" acknowledges our work

We are proud to announce that the remarkable discovery of altermagnetism of our group are presented in an article from Science News. 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.

09.03.2024 New publication about altermagnets

A publication with Jairo Sinova, Libor Šmejkal, Anna B. Hellenes, Rodrigo Jaeschke Ubiergo and Venkata K. Bharadwaj about supercell altermagnets has been published in Physical Review B.

They substantially broaden the family of altermagnetic candidates by predicting supercell altermagnets. Their magnetic unit cell is constructed by enlarging the nonmagnetic primitive unit cell, resulting in a nonzero propagation vector for the magnetic structure. This connection of the magnetic configuration to the ordering of sublattices gives an extra degree of freedom to supercell altermagnets, which can allow for the control over the order parameter spatial orientation. They identify realistic candidates MnSe2 with a d-wave order, and RbCoBr3, CsCoCr3, and BaMnO3 with g-wave order. They demonstrate the reorientation of the order parameter in MnSe2, which has two different magnetic configurations, whose energy difference is only 5 meV, opening the possibility of controlling the orientation of the altermagnetic order parameter by external perturbations.

You can find the publication under Phys. Rev. B 109, 094455 (2024).

08.03.2024 New Joint Publication in Altermagnetic Transport

A joint publication with Jairo Sinova, Libor Šmejkal, Anna B. Hellenes, Rodrigo Jaeschke Ubiergo, Warlley H. Campos, Venkata K. Bharadwaj and Atasi Chakraborty about the direct observation of altermagnetic band splitting in CrSb thin films has been published in Nature Communications.

They investigate directly this unconventional band splitting near the Fermi energy through spin-integrated soft X-ray angular resolved photoemission spectroscopy. The experimentally obtained angle-dependent photoemission intensity, acquired from epitaxial thin films of the predicted altermagnet CrSb, demonstrates robust agreement with the corresponding band structure calculations. In particular, they observe the distinctive splitting of an electronic band on a low-symmetry path in the Brilliouin zone that connects two points featuring symmetry-induced degeneracy. The measured large magnitude of the spin splitting of approximately 0.6 eV and the position of the band just below the Fermi energy underscores the significance of altermagnets for spintronics based on robust broken time reversal symmetry responses arising from exchange energy scales, akin to ferromagnets, while remaining insensitive to external magnetic fields and possessing THz dynamics, akin to antiferromagnets.

You can find the publication under Nat Commun 15, 2116 (2024).

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 Workshop on Spin textures: Magnetism meets Plasmonics

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.

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 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.

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 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.