arXiv subjects

Robin Hutt

Publications and source records attributed to Robin Hutt.

4 recordsLinked to original sources

arXiv2026

Structural Changes and Transport Properties of $\mathrm{YBa_2Cu_3O_7}$ Locally Modified by a He$^+$ Focused Ion Beam

Irradiation of a material with ions can cause various defects that can lead to structural phase transitions and the modification of the material's properties. Here we study the irradiation of the epitaxyally grown thin films of the high-temperature superconductor $\mathrm{YBa_2Cu_3O_7}$ with $30\,\mathrm{keV}$ He$^{+}$ ions which leads to the expansion of the crystal lattice, decrease of the critical temperature $T_c$ and eventually transition to an insulator. Fabrication of such insulating regions with a focused He-Ion beam with a spot size of $\sim 10\,\mathrm{nm}$ is a powerful technique for fabrication of superconducting nano-devices. Using low-temperature resistivity measurements, diffraction with a nanofocused X-ray beam and atomic force microscopy, we investigated how the structure and the electric transport properties of $\mathrm{YBa_2Cu_3O_7}$ depend on the irradiation dose in a range $10$--$100\,\mathrm{ions/nm^2}$ and on the lateral size of the irradiated area in a range $30$--$5000\,\mathrm{nm}$.

cond-mat.supr-con↗

arXiv2026

Electric-Field Control of Quantum Tunneling Regimes in Focused He-Ion-Beam-Irradiated Oxide Interfaces

Helium focused ion beam irradiation enables the fabrication of tunnel field-effect transistors based on two-dimensional electron systems (2DESs) at an oxide interface.High resolution scanning transmission electron microscopy and strain mapping reveal localized lattice deformation confined to the irradiated regions, which act as nanoscale potential barriers. The barrier profile can be continuously tuned by electrostatic backgating at low temperature without degrading the electronic properties of the 2DES electrodes. Transport measurements demonstrate controlled access to thermionic emission, direct tunneling, and Fowler-Nordheim tunneling within a single device architecture. These results establish He FIB irradiation as a powerful tool for nanoscale functional engineering of complex-oxide interfaces and provide a platform for exploring gate-tunable quantum tunneling phenomena.

cond-mat.mes-hall↗

arXiv2025

YBa$_2$Cu$_3$O$_7$ nano-constriction Josephson junctions and SQUIDs fabricated by focused helium-ion-beam irradiation

By focused $30\,\mathrm{keV}$ He ion beam irradiation, epitaxially grown YBa$_2$Cu$_3$O$_7$ (YBCO) thin films can be driven from the superconducting to the insulating state with increasing irradiation dose. A properly chosen dose suppresses superconductivity down to $4\,\mathrm{K}$, while crystallinity is still preserved. With this approach we create areas of normal-conducting YBCO that can be used to define resistively shunted constriction-type Josephson junctions (cJJs) on the nanometer scale. We also demonstrate that the fabricated cJJs can be incorporated in direct current superconducting quantum interference devices and can be used as detector junctions in THz antennas.

cond-mat.supr-con↗

arXiv2024

Vortex matching at 6 T in YBa$_2$Cu$_3$O$_{7-\delta}$ thin films by imprinting a 20 nm-periodic pinning array with a focused helium ion beam

Controlled engineering of vortex pinning sites in copper-oxide superconductors is a critical issue in manufacturing devices based on magnetic flux quanta. To address this, we employed a focused He-ion beam (He-FIB) to irradiate thin YBa$_2$Cu$_3$O$_{7-\delta}$ films and create ultradense hexagonal arrays of defects with lattice spacings as small as 20 nm. Critical current and magnetoresistance measurements demonstrate efficient pinning by an unprecedentedly high matching field of 6 T visible in a huge temperature range from the critical temperature $T_c$ down to 2 K. These results show that He-FIB irradiation provides excellent opportunities for the development and application of superconducting fluxonic devices based on Abrikosov vortices. In particular, our findings suggest that such devices can operate at temperatures far below $T_c$, where superconductivity is robust.

cond-mat.supr-con↗