Quantum Geometry and Transport of Collective Excitations in (Non-)Magnetic Insulators

Workshop, May 6th - 8th 2025

Quantum geometric properties of band structures and their signatures in experiments have driven condensed matter research over the past decades. This SPICE workshop will focus on recent theoretical and experimental advances in the topological properties of bands formed by magnetic and hybrid bosonic excitations. While the topology of electron bands is well understood, with unambiguous experimental tools to probe theoretical predictions, their bosonic analogs pose challenges. Although bosonic topological excitations, such as magnon Chern bands, Weyl and Dirac semimetals, and nodal-line semimetals have emerged, the lack of quantized responses and the ambiguity of thermal Hall and Nernst effects prevent their distinct experimental identification. Furthermore, traditional spectroscopic methods for resolving bosonic modes, such as inelastic neutron scattering, lack the contrast to resolve topological boundary states. One possible route to bring the topological excitations under control is to make use of highly tunable platforms, such as magnonic crystals and stacked van der Waals layers. Additionally, the ease of hybridization of magnonic excitations with phonons, photons, and plasmons can provide novel opportunities to directly probe the topological fingerprint.

With this workshop, we aim to provide a forum where experts and students can discuss the latest developments, challenges, and future directions in topological magnetism. Some exciting challenges that we aim to address include:

-Identify direct experimental signatures for topological bosonic excitations

-Explore the impact of many-body interactions on the quantum geometry of the single particle spectrum and transport

-Identify the microscopic origins of thermal Hall conductivity in magnetic and non-magnetic insulators

-Engineer the quantum geometry and topology of collective excitations by non-Hermitian, non-equilibrium, and Floquet control

-Explore technological applications of topological boundary modes in spintronics and magnonics

We invite contributions from the fields of magnetism, spin and heat transport, spintronics, and magnonics. In addition, we strongly encourage students to apply, and to present their work in the 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.

 

Organizers
Pieter Gunnink, JGU
Alexander Mook, JGU
Judit Romhányi, University of California

Invited Speakers

Geoffrey Diederich, University of Maryland Benedetta Flebus, Boston College Chisa Hotta, Tokyo University Johannes Knolle, TU Munich Xiaoqin Li, University of Texas-Austin Qihang Liu, SUSTech Samir Lounis, Forschungszentrum Jülich Chen Lu, LBNL Leo Mangeolle, TU Munich Aurelien Manchon, Aix-Marseille University Paul McClarty, CNRS Paris

Martin Mourigal, Georgia Tech Shuichi Murakami, Institute of Science Tokyo Joji Nasu, Tohoku University Karlo Penc, Wigner RCP Jeffrey Rau, Windsor, Canada Rolando Valdés Aguilar, Ohio State University Emil Viñas Boström, MPSD Stephen Winter, WFU Han Yan, ISSP Tokyo Emily Zhang, Stanford University Suzy Zhang, MPI PKS