6,683 research outputs found
Probing crossover from analogous weak antilocalization to localization by an Aharonov-Bohm interferometer on topological insulator surface
We propose a scanning tunneling microscopy Aharonov-Bohm (AB) interferometer
on the surface of a topological insulator (TI) to probe the crossover from
analogous weak antilocalization (WAL) to weak localization (WL) phenomenon via
the AB oscillations in spin-resolved local density of states (LDOS). Based on
our analytical and numerical results, we show that with increasing the energy
gap of TI surface states, the = periodic AB oscillations in
spin-resolved LDOS gradually transit into the periodic oscillations.Comment: 4.2 APL pages, 2 figure
Josephson Oscillation and Transition to Self-Trapping for Bose-Einstein-Condensates in a Triple-Well Trap
We investigate the tunnelling dynamics of Bose-Einstein-Condensates(BECs) in
a symmetric as well as in a tilted triple-well trap within the framework of
mean-field treatment. The eigenenergies as the functions of the zero-point
energy difference between the tilted wells show a striking entangled star
structure when the atomic interaction is large. We then achieve insight into
the oscillation solutions around the corresponding eigenstates and observe
several new types of Josephson oscillations. With increasing the atomic
interaction, the Josephson-type oscillation is blocked and the self-trapping
solution emerges. The condensates are self-trapped either in one well or in two
wells but no scaling-law is observed near transition points. In particular, we
find that the transition from the Josephson-type oscillation to the
self-trapping is accompanied with some irregular regime where tunnelling
dynamics is dominated by chaos. The above analysis is facilitated with the help
of the Poicar\'{e} section method that visualizes the motions of BECs in a
reduced phase plane.Comment: 10 pages, 11 figure
Aharonov-Bohm oscillations in the local density of topological surface states
We study Aharonov-Bohm (AB) oscillations in the local density of states
(LDOS) for topological insulator (TI) and conventional metal Au(111) surfaces
with spin-orbit interaction, which can be probed by spin-polarized scanning
tunneling microscopy. We show that the spacial AB oscillatory period in the
total LDOS is a flux quantum (weak localization) in
both systems. Remarkably, an analogous weak antilocalization with
periodic spacial AB oscillations in spin components of LDOS for TI surface is
observed, while it is absent in Au(111).Comment: 4 APL pages, 3 figure
Quantum Corrals and Quantum Mirages on the Surface of a Topological Insulator
We study quantum corrals on the surface of a topological insulator (TI).
Different resonance states induced by nonmagnetic (NM), antiferromagnetic
(AFM), and ferromagnetic (FM) corrals are found. Intriguingly, the spin is
clearly energy-resolved in a FM corral, which can be effectively used to
operate surface carrier spins of TI. We also show that an observable quantum
mirage of a magnetic impurity can be projected from the occupied into the empty
focus of a FM elliptic corral, while in NM and AFM corrals the mirage signal
becomes negligibly weak. In addition, the modulation of the interaction between
two magnetic impurities in the quantum corrals is demonstrated. These prominent
effects may be measured by spin-polarized STM experiments.Comment: 5 PRB pages, 4 figure
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