Tunable High Speed Atomic Rotor in Bi₂Se₃ Revealed by Current Noise

Abstract

The ability to manipulate individual atoms and molecules using a scanning tunneling microscope (STM) has been crucial for the development of a vast array of atomic-scale devices and structures ranging from nanoscale motors and switches to quantum corrals. Molecular motors in particular have attracted considerable attention in view of their potential for assembly into complex nanoscale machines. Whereas the manipulated atoms or molecules are usually on top of a substrate, motors embedded in a lattice can be very beneficial for bottom-up construction, and may additionally be used to probe the influence of the lattice on the electronic properties of the host material. Here, we present the discovery of controlled manipulation of a rotor in Fe doped Bi 2 Se 3 . We find that the current into the rotor, which can be finely tuned with the voltage, drives omni-directional switching between three equivalent orientations, each of which can be frozen in at small bias voltage. Using current fluctuation measurements at 1 MHz and model simulations, we estimate that switching rates of hundreds of kHz for sub-nanoampere currents are achieved.

Formation and Manipulation of Diatomic Rotors at the Symmetry-Breaking Surfaces of a Kagome Superconductor

“…Very recently, Desvignes et al reported a diatomic rotor in Fe doped Bi 2 Se 3 where the atomically sized Fe defect is embedded in the crystal structure. 28 Here we report, for the first time, the construction of a Cr− Cs/Fe−Cs diatomic rotor in a newly discovered kagome superconductor CsV 3 Sb 5 , 29,30 which has been reported to exhibit rich surface effects such as symmetry breaking orders, 31−36 carrier doping, 37,38 and polarity. 39 switching rates suggests the effects of symmetry breaking charge orders on the rotors.…”

“…Such a strategy also inspires the search for a diatomic rotor. Very recently, Desvignes et al reported a diatomic rotor in Fe doped Bi 2 Se 3 where the atomically sized Fe defect is embedded in the crystal structure …”

Magnetic Gap of Fe-Doped BiSbTe2Se Bulk Single Crystals Detected by Tunneling Spectroscopy and Gate-Controlled Transports

“…The tetradymites have layered crystal structures (Figure a). We should care about the unintended intergrowth of magnetic impurities of Fe–Se compounds promoted by Fe doping. − This intergrowth may occur over a certain temperature range and be easily driven by an inhomogeneous Fe distribution. Indeed, owing to special care such as homogeneous mixing at high temperatures and rapid quenching, we grew Fe-doped Bi 2 Te 2 Se and Fe-doped BiSbTe 2 Se (Fe-BSTS) as high bulk-insulating magnetically doped TIs , and reported observation of unusual proximity effects .…”