New Spin on Molecular Quantum Materials

Stabilizing fragile quantum states necessitates understanding and control of multiple material variables. Molecular quantum materials provide a test field for models and theory due to their high chemical variability, large compressibility and the possibility of systematic disorder tuning. This workshop fosters the interaction between theory and experiment, particularly addressing scientists previously not engaged in organic materials.
The recent years saw considerable advancements, but also a dichotomy between experiment and theory. For instance, the nature of quantum-spin-liquid and charge-dipole-liquid states in κ-phase BEDT-TTF salts remains controversial. On the other hand, anomalous transport in bad and strange metals near electronic instabilities awaits a solid theoretical description.
Those phenomena rely on a suppression of effective energy scales via frustration or competing orders, making molecular quantum materials susceptible to many sub-dominant factors such as magneto-elastic coupling, disorder and spin-orbit effects. To that end, the workshop will stimulate exchange among different fields, especially focusing on spin vs charge degrees of freedom, insulators vs metals, transport vs thermodynamic methods and non-equilibrium vs equilibrium probes.

Ultrafast Antiferromagnetic Writing

While recent developments in photonics enable nearly lossless data transfer with speeds exceeding 1 Tb/s, current magnetic data storage cannot keep up with these data-flow rates nor decrease energy dissipations. Consequently, already now data centres are becoming the biggest consumers of electricity world-wide. Antiferromagnets represent a highly-promising playground for the quest for the fastest and the least-dissipative mechanism of data storage. However, in thermodynamic equilibrium, the energy of interaction of a magnetic field with the antiferromagnetic Néel vector is zero. Despite the 60-year long search for thermodynamic conjugates to the antiferromagnetic order parameter, efficient means to control antiferromagnetism are still being pursued. It is the main reason that hampers applications of antiferromagnets and further development of antiferromagnetic spintronics, magnonics and data storage, in particular.
Although many experimental and theoretical studies make us believe that ultrafast writing of bits in antiferromagnets at THz rates must be possible, such an ultrafast writing has never been demonstrated in antiferromagnetic media and the highest frequency of rewriting of magnetic bits (100 GHz) belongs to ferrimagnets. The landmark of 1 THz remains to be a monumental challenge.
The goal of the workshop is to bring together experts in ultrafast switching of antiferromagnetism, review the state-of-the-art, discuss the present challenges, define short- as well as long-term goals in the field with the ultimate goal to initiate a breakthrough towards the fastest ever and least dissipative writing of magnetic bits.

Understanding the complex phases of matter which are intertwined with each other has always been on the forefront of research in condensed matter physics. However, the immensely complex nature of interacting many body systems requires specialized understanding both theoretically and experimentally, which break down the many body interactions into more tangible parts to describe the rich abundance of phenomena we observe in nature. Prominent examples include - spin density wave, charge density wave, unconventional superconductivity, topological insulators, just to name a few.
Within this summer school we aim to educate our young PhD students on a broad range of emergent phenomena within this field. Since most come from diverse backgrounds, not only having different levels of experiences with theory or state of the art experiments, but also different topics of expertise within the field of condensed matter itself, we aim to broaden their knowledge and extend their horizon with this 4 days online summer school.
Hence, the lectures given by experts in their respective fields of condensed matter, will introduce some important scientific questions and challenges of their fields, reaching both theoretical and experimental aspects of research.

Driven-dissipative quantum many body systems constitute a cross- disciplinary frontier of research encompassing condensed matter, AMO and solid state physics. Many-particle systems where quantum coherent dynamics and dissipative effects occur on the same footing, find experimental realization in cavity QED, driven open Rydberg systems, trapped ions, exciton-polariton condensates, coupled micro- cavity arrays — among the others.
These platforms offer the unique opportunity to explore extensive phases of matter which cannot be encompassed through conventional statistical mechanics. At the same time they pose a number of fundamental and technical challenges. The ubiquitous intrusive effect of dissipation in experiments, confronts researchers to optimize and enhance the role of quantum fluctuations in strongly noisy and decoherent environments. At the same time, an efficient simulation of open many-particle systems require a formidable combination of techniques and expertise ranging from advanced field theoretical methods to forefront numerical techniques, from machine learning to non-unitary versions of techniques from the field of strongly correlated systems.
These 3-days workshop will bring together a number of experts from a diverse and interdisciplinary set of fields, including condensed matter physics, cold atoms, quantum engineering, quantum optics, atomic and solid state physics, with a broad selection of experimentalists from currently active fields. Ample space will be devoted to the participation of emergent and promising young scholars with dedicated flash talks in a 'March Meeting' format. Furthermore, the workshop hosted two topical sessions to foster dialogue among researchers belonging to different sub-communities.

What once began with spin-polarized electric currents in ferromagnets and the giant magnetoresistance, today is an internationally overarching research field known as spintronics. The last two decades, in particular, saw the consolidation of spintronics into modern solid state research. This was possible in large parts thanks to the experimental confirmation of the spin Hall effect and its inverse counterpart that enables electrical detection of pure spin currents. By now, it is known that the electronic spin not only couples to magnetic but also electric fields as well as heat gradients, adding interconversion phenomena between spin, charge, and heat to the spintronic inventory, examples being the spin Seebeck, spin Nernst, and Edelstein effects. Being inspired by both the uncovering of fundamental physics as well as the vision that spin will serve as an information carrier, the spintronics community studied a broad range of material classes, including normal, topological, and magnetic metals as well as topological and magnetic insulators. Magnets, in particular, proved to contain a wealth of surprises, exemplified by topological magnons, topological (spin) Hall effects in skyrmion crystals, anomalous Hall effects in antiferromagnets, or the magnetic spin Hall effect.

This SPICE Young Research Leaders Group Workshop serves as a melting pot of ideas on how to tackle the major spintronic challenges of this decade. The program of this workshop is built around the following major questions:
(1) Relying on symmetry arguments, which transport phenomena do we expect?
(2) How does the topological nontriviality of the electronic or magnonic band structure influences spin, charge, and heat transport?
(3) Which materials show particularly large transport and why? (Can we engineer spin transport?)
(4) How do we perform clear-cut experiments to disentangle a particular (spin) transport phenomenon from others?
(5) How do we use the arsenal of spintronics as means to explore and characterize complex materials?

Topology in quantum mechanics is applied to determine if a system is trivial or topological. A condensed matter system has a topological nature if the general wavefunction describing it is adiabatically distinct from the atomic limit. Although nontrivial topology has been known to exist in quantum Hall systems for nearly four decades, recent years have seen a massive resurgence in the interest of topological matter stemming from a series of ground-breaking discoveries. In many cases, topological quantum mechanics is achieved in systems involving superconductors with highlights including: Majorana Fermions in nanowire devices; unconventional electron pairing in layered oxides and the decoding high temperature superconductivity; superconducting thin films of strontium ruthenate; topological superconductivity in UTe2; coupling superconductivity into chiral (topological) molecules; and topological superconductivity and magnetism in twisted bilayer graphene.

The incredible progress made in materials research over the past decade and half has been central to the rapid development of unconventional superconductivity in topological quantum materials. These include the development of atomically-controlled crystals, thin films and interfaces, and the manipulation of pristine two-dimensional materials and superlattices. The widespread interest and progress in unconventional superconductivity and topology in such advanced materials continues to accelerate; however, a targeted, interdisciplinary, approach is required in order to achieve full understanding and the discovery of new science. This workshop brings together world-leading scientists from a broad range of disciplines working on overlapping themes involving correlated electrons and superconductivity in topological systems. These communities had an opportunity to appreciate how these areas are interlinked thereby stimulating further understanding and new collaborations.