Condensed Matter Physics in the Alps: Geometric Frustration, Topology, Flat Bands, and Correlation in Kagome and Van der Waals Systems

Session

Monday Afternoon Session, Chair D. Mihailovic

5 Jan 2026, 17:00

Saas Fee

22. The puzzle of metallic and insulating phases at the surface of 1T-TaSe2

Michael Straub (University of Geneva)

05/01/2026, 17:00

van der Waals experimental

Contributed talk

In the layered transition-metal dichalcogenide 1T-TaSe$_2$ the formation of a star-of-David charge density wave results in a half-filled band at the Fermi surface that is sensitive to electron correlations. Interestingly, while the bulk material remains a metal, the surface displays a mix of different phases, ranging from insulating to metallic, all with the same in-plane charge ordering.
We...

52. Interlayer stacking controls the electronic properties of the van der Waals material 1T-TaS2

Simon Gerber (PSI - Paul Scherrer Institut)

05/01/2026, 17:20

van der Waals experimental

Invited talk (by invitation only)

Given the small binding between layers, stacking of van der Waals materials is a powerful tool for exploring the physics of quantum condensed matter. However, exploitation for engineering will require taking advantage of thicker defective stacks, or an ability to control the stacking order via external stimuli, such as electrical or optical pulses.

I will present X-ray diffraction data of...

51. Magnetic order and interactions in two polytypes of V1/3NbS2

Collin Broholm (Johns Hopkins University)

05/01/2026, 17:55

van der Waals experimental

Invited talk (by invitation only)

Magnetically intercalated transition metal dichalcogenides (TMDs) provide a versatile three-dimensional (3D) material platform to explore quantum phenomena and functionalities that emerge from an intricate interplay between magnetism, band structure, and correlations.
I shall describe the observation of a nearly magnetization-free anomalous Hall effect (AHE) in V1/3NbS2. Our single-crystal...