Project B02: Nanoscale 2017

Self-assembled monolayer field-effect transistors based on oligo-9,9'-dioctylfluorene phosphonic acids

The use of functional oligomers of π-conjugated oligofluorenes led to a region-selective assembly of amorphous monolayers which exhibit robust lateral charge transport pathways in self-assembled monolayer field-effect transistors over long distances and even in mixed monolayers of semiconducting and insulating molecules. This oligomer concept might stimulate a new molecular design of...

Read more

Project C10: Phys. Rev. B 2017

Temperature scaling of the Dzyaloshinsky-Moriya interaction in the spin wave spectrum

The temperature scaling of the micromagnetic Dzyaloshinsky-Moriya exchange interaction is calculated from saturated to vanishing magnetization. We use Green's function theory to derive the finite-temperature spin wave spectrum of ferromagnetic systems described by a classical atomistic spin model Hamiltonian with temperature-independent parameters. Within this model, we find universal expressions for the...

Read more

Project C03: Physical Review B 2017

Charge-vibration interaction effects in normal-superconductor quantum dots

We study the quantum transport and the nonequilibrium vibrational states of a quantum dot embedded between a normal-conducting and a superconducting lead with the charge on the quantum dot linearly coupled to a harmonic oscillator of frequency ω. To the leading order in the charge-vibration interaction, we calculate the current and the nonequilibrium phonon occupation by the Keldsyh Green's function technique. We analyze...

Read more

Project A07: Physical Review Letter 2017

Parametric Oscillation, Frequency Mixing, and Injection Locking of Strongly Coupled Nanomechanical Resonator Modes

Enforcing discipline on nanomechanical vibration

When one strongly shakes a pendulum close to its resonance frequency, it eventually locks to the shaking, i.e. tightly follows the applied force. Here we investigate such phenomena for two orthogonal vibrations of a nanomechanical string resonator which is five hundred times smaller than a human hair and embedded in an all...

Read more

Project A01: Physical Review 2017 (Editors' Suggestion)

Acoustic waves undetectable by transient reflectivity measurements

In laser ultrasonics, ultrashort light pulses generate coherent acoustic pulses of picosecond duration via multiple possible physical mechanisms, involving optoacoustic conversion processes. These wide-band GHz acoustic signals are optically detected at the sample surfaces by ultrafast time-delayed probe light pulses. When the coherent acoustic pulses in GaAS are detected via the Brillouin scattering of probe light pulses of 400...

Read more

Project A07: New Journal of Physics 2017

Finite-time Stückelberg interferometry with nanomechanical modes

Stückelberg interferometry describes the interference of two strongly coupled modes during a double passage through an avoided energy level crossing. In this work, we investigate finite-time effects in Stückelberg interferometry and discuss the exact analytical solution of the double passage Stückelberg problem by expanding the finite-time solution of the Landau–Zener problem. Approximating the return probability amplitudes of the...

Read more

Project C13: Science 2017

Quantized Thermal Transport in Single Atom Junctions

Thermal transport in individual atomic junctions and chains is of great fundamental interest due to unique quantum effects expected to arise in them. Here, by employing novel, custom-fabricated, picowatt-resolution calorimetric scanning probes, we measure the thermal conductance of gold and platinum metallic wires down to single-atom junctions. Our work reveals that the thermal conductance of gold single atom junctions is quantized at room...

Read more

Project C04: Nature Communincations 2017

Correlation Driven Transport Asymmetries Through Coupled Spins in a Tunnel Junction

Spin–spin correlations are fundamental to many material properties because they favor certain ground states and are key in numerous models that describe the behavior of strongly correlated materials. While the sum of collective correlations usually lead to a macroscopically measurable change in properties, a direct quantification of correlations in atomic scale systems is difficult.
Using a scanning tunneling...

Read more

Project C13/C14 - Chem. Eur. Journal

Redox-Active Tetraruthenium Macrocycles Built from 1,4-Divinylphenylene-Bridged Diruthenium Complexes

Metallamacrocylic tetraruthenium complexes were generated by treatment of 1,4-divinylphenylene-bridged diruthenium complexes with functionalized 1,3-benzene dicarboxylic acids and characterized by HR ESI-MS and multinuclear NMR spectroscopy. Every divinylphenylene diruthenium subunit is oxidized in two consecutive one-electron steps with half-wave potential splittings in the range of 250 to 330...

Read more

Project B08: Nature Photonics 2017

Sub-cycle optical phase control of nanotunnelling in the single-electron regime

The high peak electric fields provided by single-cycle light pulses can be harnessed to manipulate and control charge motion in solid-state systems, resulting in electron emission out of metals and semiconductors or high harmonics generation in dielectrics. These processes are of a non-perturbative character and require precise reproducibility of the electric-field profile.
Here, we vary the carrier-envelope phase of...

Read more