One-dimensional Luttinger liquids in a two-dimensional moiré lattice.

The Luttinger liquid (LL) model of one-dimensional (1D) electronic systems provides a powerful tool for understanding strongly correlated physics, including phenomena such as spin-charge separation. Substantial theoretical efforts have attempted to extend the LL phenomenology to two dimensions, especially in models of closely packed arrays of 1D quantum wires, each being described as a LL. Such coupled-wire models have been successfully used to construct two-dimensional (2D) anisotropic non-Fermi liquids, quantum Hall states, topological phases and quantum spin liquids.

Holistic View on Materials Development: Water Electrolysis as a Case Study.

In view of rising ecological awareness, materials development is primarily aimed at improving the performance and efficiency of innovative and more elaborate materials. However, a materials performance figure of merit should include essential aspects of materials: environmental impact, economic constraints, technical feasibility, etc. Thus, we promote the inclusion of sustainability criteria already during the materials design process.

Landau quantization and highly mobile fermions in an insulator.

In strongly correlated materials, quasiparticle excitations can carry fractional quantum numbers. An intriguing possibility is the formation of fractionalized, charge-neutral fermions-for example, spinons and fermionic excitons-that result in neutral Fermi surfaces and Landau quantization in an insulator. Although previous experiments in quantum spin liquids, topological Kondo insulators and quantum Hall systems have hinted at charge-neutral Fermi surfaces, evidence for their existence remains inconclusive.