PSI Center for Neutron and Muon Sciences

Exchange interactions are mediated via orbital overlaps across chemical bonds. Thus, modifying the bond angles by physical pressure or strain can tune the relative strength of competing interactions. Here we present a remarkable case of such tuning between the Heisenberg (J) and Kitaev (K) exchange, which respectively establish magnetically ordered and spin liquid phases on a honeycomb lattice. We observe ...

Kagome metals with van Hove singularities near the Fermi level can host intriguing quantum phenomena such as chiral loop currents, electronic nematicity, and unconventional superconductivity. However, to our best knowledge, unconventional magnetic states driven by van Hove singularities–like spin-density waves–have not been observed experimentally in kagome metals. Here, we report ...

The interplay between topology and superconductivity generated great interest in condensed matter physics. Here, we unveil an unconventional two-dimensional superconducting state in the Dirac nodal line semimetal ZrAs₂ which is exclusively con ned to the top and bottom surfaces within the crystal’s ab plane. 

As a remarkable consequence ...

Crystalline solids can become band insulators due to fully lled bands, or Mott insulators due to strong electronic correlations. While Mott insulators can theoretically occur in systems with an even number of electrons per unit cell, distinguishing them from band insulators experimentally has remained a longstanding challenge. 

In this work, we present ...

The topological nature of the electronic bands or spin structure has direct manifestation in experimentally measured Hall conductivity. The extra topological (or geometrical) component to the Hall effect (THE) usually emerges due to multi-k structures, which inherently possess a finite static scalar spin chirality (SSC). Generating a THE in a single-k structure necessitates the consideration of the dynamical  origin of SSC, the real material examples of such cases remain scarce to date.