21 research outputs found
Multiple Avalanches Across the Metal-Insulator Transition of Vanadium Oxide Nano-scaled Junctions
The metal insulator transition of nano-scaled devices is drastically
different from the smooth transport curves generally reported. The temperature
driven transition occurs through a series of resistance jumps ranging over 2
decades in amplitude, indicating that the transition is caused by avalanches.
We find a power law distribution of the jump amplitudes, demonstrating an
inherent property of the films. We report a surprising relation between
jump amplitude and device size. A percolation model captures the general
transport behavior, but cannot account for the statistical behavior.Comment: 4 papers and 4 figures submitted to PR
Temperature-dependence of the chirality-induced spin selectivity effect -- experiments and theory
The temperature dependence of the chirality-induced spin selectivity (CISS)
effect can be used to discriminate between different theoretical proposals for
the mechanism of the CISS effect. Here we briefly review key experimental
results and discuss the effect of temperature in different models for the CISS
effect. We then focus on the recently suggested spinterface mechanism and
describe the different possible effects temperature can have within this model.
Finally, we analyze in detail recent experimental results from Qian, et.al.,
(Nature, 606, 902-908 (2022)) and demonstrate that, opposite to the original
interpretation by the authors, these data indicate that the CISS effect
increases with decreasing temperature. Finally, we show how the spinterface
model can accurately reproduce these experimental results.Comment: Author sequence changed, substantially expanded and version published
in the Journal of Chemical Physic
Anomalous proximity effect in gold coated (110) films: Penetration of the Andreev bound states
Scanning tunneling spectroscopy of (110) bi-layers
reveal a proximity effect markedly different from the conventional one. While
proximity-induced mini-gaps rarely appear in the Au layer, the Andreev bound
states clearly penetrate into the metal. Zero bias conductance peaks are
measured on Au layers thinner than 7 nm with magnitude similar to those
detected on the bare superconductor films. The peaks then decay abruptly with
Au thickness and disappear above 10 nm. This length is shorter than the normal
coherence length and corresponds to the (ballistic) mean free path.Comment: 5 prl format pages, 4 figures, to be published in PR
Control of spin injection by direct current in lateral spin valves
The spin injection and accumulation in metallic lateral spin valves with
transparent interfaces is studied using d.c. injection current. Unlike
a.c.-based techniques, this allows investigating the effects of the direction
and magnitude of the injected current. We find that the spin accumulation is
reversed by changing the direction of the injected current, whereas its
magnitude does not change. The injection mechanism for both current directions
is thus perfectly symmetric, leading to the same spin injection efficiency for
both spin types. This result is accounted for by a spin-dependent diffusion
model. Joule heating increases considerably the local temperature in the spin
valves when high current densities are injected (80--105 K for
1--2A cm), strongly affecting the spin accumulation.Comment: 6 pages, 5 figure