Nanosystems Initiative Munich

About: Nanosystems Initiative Munich is a facility organization based out in Munich, Germany. It is known for research contribution in the topics: Quantum dot & Perovskite (structure). The organization has 323 authors who have published 549 publications receiving 24316 citations.

Role of interface quality for the spin Hall magnetoresistance in nickel ferrite thin films with bulk-like magnetic properties

Abstract: We utilized spin Hall magnetoresistance (SMR) measurements to experimentally investigate pure spin current transport in thin film heterostructures of nickel ferrite (NiFe2O4,NFO) and normal metals (NM) Ta and Pt. We grew (001)-oriented NFO thin films by pulsed laser deposition on lattice-matched magnesium gallate (MgGa2O4) substrates, thereby significantly improving their magnetic and structural properties. We performed SMR measurements at room temperature in patterned Hall bar structures for charge currents applied in the [100]- and [110]-directions of NFO. We found that the extracted SMR magnitude for NFO/Pt heterostructures depends crucially on the Pt resistivity of the investigated Hall bar structure. We further study this resistivity scaling of the SMR effect at different temperatures for NFO/Pt. Our results suggest that the spin mixing conductance of the NFO/Pt interface and the Pt resistivity depend on the interface quality and thus a correlation between these two quantities exists.

Non-monotonic temperature dependence of chaos-assisted diffusion in driven periodic systems

Abstract: The spreading of a cloud of independent Brownian particles typically proceeds more effectively at higher temperatures, as it derives from the commonly known Sutherland-Einstein relation for systems in thermal equilibrium. Here, we report on a non-equilibrium situation in which the diffusion of a periodically driven Brownian particle moving in a periodic potential decreases with increasing temperature within a finite temperature window. We identify as the cause for this non-intuitive behaviour a dominant deterministic mechanism consisting of a few unstable periodic orbits embedded into a chaotic attractor together with thermal noise-induced dynamical changes upon varying temperature. The presented analysis is based on extensive numerical simulations of the corresponding Langevin equation describing the studied setup as well as on a simplified stochastic model formulated in terms of a three-state Markovian process. Because chaos exists in many natural as well as in artificial systems representing abundant areas of contemporary knowledge, the described mechanism may potentially be discovered in plentiful different contexts.

Breakdown of Corner States and Carrier Localization by Monolayer Fluctuations in Radial Nanowire Quantum Wells.

Abstract: We report a comprehensive study of the impact of the structural properties in radial GaAs-Al0.3Ga0.7As nanowire-quantum well heterostructures on the optical recombination dynamics and electrical transport properties, emphasizing particularly the role of the commonly observed variations of the quantum well thickness at different facets. Typical thickness fluctuations of the radial quantum well observed by transmission electron microscopy lead to pronounced localization. Our optical data exhibit clear spectral shifts and a multipeak structure of the emission for such asymmetric ring structures resulting from spatially separated, yet interconnected quantum well systems. Charge carrier dynamics induced by a surface acoustic wave are resolved and prove efficient carrier exchange on native, subnanosecond time scales within the heterostructure. Experimental findings are corroborated by theoretical modeling, which unambiguously show that electrons and holes localize on facets where the quantum well is the thickes...

The free energy landscape of retroviral integration

Abstract: Retroviral integration, the process of covalently inserting viral DNA into the host genome, is a point of no return in the replication cycle. Yet, strand transfer is intrinsically iso-energetic and it is not clear how efficient integration can be achieved. Here we investigate the dynamics of strand transfer and demonstrate that consecutive nucleoprotein intermediates interacting with a supercoiled target are increasingly stable, resulting in a net forward rate. Multivalent target interactions at discrete auxiliary interfaces render target capture irreversible, while allowing dynamic site selection. Active site binding is transient but rapidly results in strand transfer, which in turn rearranges and stabilizes the intasome in an allosteric manner. We find the resulting strand transfer complex to be mechanically stable and extremely long-lived, suggesting that a resolving agent is required in vivo.

Optical Emission Spectroscopy Study of Competing Phases of Electrons in the Second Landau Level.

Abstract: Quantum phases of electrons in the filling factor range 2≤ν≤3 are probed by the weak optical emission from the partially populated second Landau level and spin wave measurements. Observations of optical emission include a multiplet of sharp peaks that exhibit a strong filling factor dependence. Spin wave measurements by resonant inelastic light scattering probe breaking of spin rotational invariance and are used to link this optical emission with collective phases of electrons. A remarkably rapid interplay between emission peak intensities manifests phase competition in the second Landau level.