Christoph Stampfer had the opportunity to share more about our institute's experience with LLMs in physics teaching, especially with LandauAI (many thanks to Jan-Lucas Uslu) at the annual workshop of the "Studiendekan*innen" of RWTH Aachen University at Burg Obbendorf in Niederzier.

Scientists from the Peter Grünberg Institute (PGI) gathered today for the annual PGI-Forum to share research updates, spark new collaborations, and exchange ideas. Christoph Stampfer's presentation on "2D Materials for Next Generation Computing" sparked engaging discussions. Once again, the forum proved to be a very lively event.

We warmly congratulate our former Bachelor’s and Master’s student, Jan-Lucas Uslu, on being admitted to the PhD program at the Department of Applied Physics at Stanford (California, USA). We a wish Jan-Lucas great success in his research and future endeavours!

As the festive season approaches quickly, we at the 2D Materials and Quantum Devices Group would like to extend our warmest wishes to all for a Merry Christmas and a Happy New Year 2025!

2D Materials 12, 015017 (2025)
We present a benchmarking protocol that combines the characterization of boron nitride (BN) crystals and films with the evaluation of the electronic properties of graphene on these substrates. Our study includes hBN crystals grown under different conditions (atmospheric pressure high temperature, high pressure high temperature, pressure controlled furnace) and scalable BN films deposited by either chemical or physical vapor deposition (CVD or PVD). We explore the complete process from boron nitride growth, over its optical characterization by time-resolved cathodoluminescence (TRCL), to the optical and electronic characterization of graphene by Raman spectroscopy after encapsulation and Hall bar processing. Within our benchmarking protocol we achieve a homogeneous electronic performance within each Hall bar device through a fast and reproducible processing routine. We find that a free exciton lifetime of 1 ns measured on as-grown hBN crystals by TRCL is sufficient to achieve high graphene room temperature charge carrier mobilities of 80,000 cm²/(Vs) at a carrier density of |n| = 10¹² cm^-2, while respective exciton lifetimes around 100 ps yield mobilities up to 30,000 cm²/(Vs). For scalable PVD-grown BN films, we measure carrier mobilities exceeding 10,000 cm²/(Vs) which correlates with a graphene Raman 2D peak linewidth of 22 cm^-1. Our work highlights the importance of the Raman 2D linewidth of graphene as a critical metric that effectively assesses the interface quality (i.e. surface roughness) to the BN substrate, which directly affects the charge carrier mobility of graphene. Graphene 2D linewidth analysis is suitable for all BN substrates and is particularly advantageous when TRCL or BN Raman spectroscopy cannot be applied to specific BN materials such as amorphous or thin films. This underlines the superior role of spatially-resolved spectroscopy in the evaluation of BN crystals and films for the use of high-mobility graphene devices.

We are very happy to share that Luca Banszerus, former PhD student in our group, started in December 2024 as Assistant Professor at the Faculty of Physics of the University of Vienna.

He leads the newly founded Quantum Transport Lab, focusing on the electronic properties of mesoscopic devices based on low-dimensional materials, at the interface of fundamental condensed matter physics and novel quantum devices. More information on his research interests and publications can be found on his group’s website.

Congratulations, Luca, on this exciting new career step. We wish you a great start and all the best for this new chapter!

Today, Bernd Beschoten from our group fascinated the audience with his "November-Vorlesung", i.e. talk on the world's shortest light pulses: femtoseconds and attoseconds. A truly inspiring journey through cutting-edge physics!

ACS Nano 18, 32924 (2024)
Magnetic 2D materials enable interesting tuning options of magnetism. As an example, the van der Waals material FePS₃, a zig-zag-type intralayer antiferromagnet, exhibits very strong magnetoelastic coupling due to the different bond lengths along different ferromagnetic and antiferromagnetic coupling directions enabling elastic tuning of magnetic properties. The likely cause of the length change is the intricate competition between direct exchange of the Fe atoms and superexchange via the S and P atoms. To elucidate this interplay, we study the band structure of exfoliated FePS₃ by μm scale ARPES (angular resolved photoelectron spectroscopy), both, above and below the Néel temperature TN. We found three characteristic changes across TN. They involve S 3p-type bands, Fe 3d-type bands and P 3p-type bands, respectively, as attributed by comparison with density functional theory calculations (DFT + U). This highlights the involvement of all the atoms in the magnetic phase transition providing independent evidence for the intricate exchange paths.