Selected Application
Dynamic Visualization of Nanoscale Vortex Motion using
attoSTM* in an attoLiquid3000
Matias Timmermans and co-workers invented an innovative technique removing
the lack of temporal resolution in STM imaging [1]. They used an attoSTM in an
attoLIQUID3000 3He cryostat to measure and study vortex motion in 2H‑NbSe2
on a much shorter time scale. By applying a small AC magnetic field they induced a
periodic movement of the vortices. The external perturbation results in a distinct
smearing of the vortex in the images. Instead of collecting several consecutive images, the tunneling current is recorded at each point over three cycles of the excitation. The exceptional thermal and spatial stability of the attoSTM in the attoLiquid3000 allows further analysis of the time dependence of this signal at each point.
Using an additional lock-in technique more details and understanding of the vortex
motion is revealed. By mapping the first and a second harmonic of the tunneling
signal (see upper figures), they were able to visualize changes of the vortex lattice
when the vortex density is increased by increasing the DC magnetic field.
In a next step, they used the AC excitation as a time reference to track the motion
of individual vortices in time. This results in time resolved snapshots of the vortex
motion, which allows them to construct a movie frame by frame. This visualization
procedure is unprecedented and promises a much better understanding of the dynamical behavior of the superconducting condensate (see lower figures). Contrary
to the expectation the vortex does not move in a line but follows a circular motion,
due to a potential created by atoms and/or vortices.
For further reading see attocube Application Note M46.
[1] M. Timmermans, T. Samuely, B. Raes, J. Van de Vondel, V. V. Moshchalkov, ACS Nano 8, 2782 (2014)
All figures adopted with permission from M. Timmermans, et al. ACS Nano 8, 2782 (2014). Copyright 2014 American
Chemical Society.
Further attoSTM applications:
[2] M. Timmermans, T. Samuely, B. Raes, J. Van de Vondel, V.V. Moshchalkov,Physica C 503, 154–157 (2014)
[3] G. Zhang et al., Advanced Materials 26 (13), 2034–2040, (2014)
*the application shown here makes reference to the following products: attoLIQUID3000 with the dedicated
attoSTM (not shown here). In contrast to the attoAFM/STM, it is based on a tube scanner with smaller scan
range but enhanced stability, and a wire-type tip without tuning fork, and hence without AFM capabilities.
Please contact attocube for more information.
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