Selected Applications
scanning probe microscopy at mK temperatures
Quantized Conduction on Domain Walls
of a Magnetic Topological Insulator
500 nm
In a paper published in Science, researchers from the University of Tokyo and RIKEN (Japan) have
studied quantized conduction on domain walls of a magnetic topological insulator using an
attoAFM/MFM in a 3He-cryostat down to 500 mK. In their paper, Yasuda et al. designed and
created magnetic domains in the quantum anomalous Hall state, and proved the existence of the
chiral one-dimensional edge conduction along the domain walls through transport measurements. This
discovery would permit fully electrical control of the mobile domain walls and chiral edge states,
which may lead to the realization of low-power-consumption spintronic, memory and quantum
information processing devices in the future.
Further Readings:
[1] K. Yasuda et al., Science 358, 1311 (2017)
Scanning Gate Microscopy at 300 mK
In this measurement, an attoAFM III was operated inside an attoLIQUID3000 cryostat at 300 mK in
scanning gate microscopy mode (SGM) - investigating the trajectory and interaction of edge channels
of a split-gate quantum point contact (QPC) device in the quantum Hall (QH) regime. By scanning the
SGM tip over the surface of the QPC at constant height and by simultaneously measuring and plotting
the source-drain current, conductance maps were obtained. The image to the left is an example of
such a conductance map depicting the characteristic branched-flow of electrons at zero magnetic
field, which in turn shows electron interference fringes and the actual electron path
(T = 400 mK, 2DEG density n 2D = 3.37 x 10 11 cm -2 )
Further Readings:
[1] N. Paradiso et al., Physica E 42, 1038 (2010)
[2] N. Paradiso et al., Phys. Rev. Lett. 108, 246801 (2012)
[3] L. Bours et al., Phys. Rev. B 96, 195423 (2017)