Room temperature memristive switching in nano-patterned LaAlO₃/SrTiO₃ wires with laterally defined gates

We present room temperature memristive switching in a nano-patterned LaAlO₃/SrTiO₃ wire with laterally defined gates in proximity to the wire. Closed bias voltage sweeps show pinched hysteresis loops with zero bias resistance values of up to R_on = 8 MΩ and R_off = 1.2 GΩ for the on and off state, respectively. The maximum R_off/R_on ratio is 150. [...]

Appl. Phys. Lett. 118, 153502 (2021)

Momentum for Catalysis: How Surface Reactions Shape the RuO₂ Flat Surface State

The active (110) surface of the benchmark oxygen evolution catalyst RuO₂ spans a flat-band surface state (FBSS) between the surface projections of its Dirac nodal lines (DNLs) that define the electronic properties of this functional semimetal. Monitoring well-known surface adsorption processes of H₂, O₂, NO, and CO by in operando angle-resolved photoemission spectroscopy, we selectively modify the oxidation state of individual Ru surface sites and identify the electronic nature of the FBSS: [...]

ACS Catal. 2021, 11, 1749−1757

Radial Spin Texture of the Weyl Fermions in Chiral Tellurium

Trigonal tellurium, a small-gap semiconductor with pronounced magneto-electric and magneto-optical responses, is among the simplest realizations of a chiral crystal. We have studied by spin- and angleresolved photoelectron spectroscopy its unconventional electronic structure and unique spin texture. We identify Kramers–Weyl, composite, and accordionlike Weyl fermions, so far only predicted by theory, and show that the spin polarization is parallel to the wave vector along the lines in k space connecting high-symmetry points. [...]

Phys. Rev. Lett. 2020, 125 (21), 216402

Nanophysics at surfaces

The research activities of our group are concerned with the physics of low-dimensional systems, where the electron states resulting from dimensional confinement lead to unusual conduction properties and to phase transitions as a function of temperature.

Oxide interfaces

Our group focusses on the electronic structure of correlated systems in transition metal oxides (TMOs). Special interest lies in the interplay of different degrees of freedom (charge, spin, orbital, lattice) in the light of metal-insulator and other phase transitions.

Neutron and resonant X-ray spectroscopy

In our group we investigate complex, functional materials such as transition metal oxides, which are used in the emerging field of correlated nanoelectronics. Unlike with conventional semiconductors, exotic superconducting, orbital and magnetic states can be realized at the interfaces in layered structures comprising such materials.