3,167 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
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
Flares from merged magnetars: their prospects as a new population of gamma-ray counterparts of binary neutron star mergers
Long-lived massive magnetars are expected to be remnants of some binary
neutron star (BNS) mergers. In this paper, we argue that the magnetic powered
flaring activities of these merged magnetars would occur dominantly in their
early millisecond-period-spin phase, which is in the timescale of days. Such
flares endure significant absorption by the ejecta from the BNS collision, and
their detectable energy range is from 0.1-10 MeV, in a time-lag of days
after the merger events indicated by the gravitational wave chirps. We estimate
the rate of such flares in different energy ranges, and find that there could
have been ~0.1-10 cases detected by Fermi/GBM. A careful search for
milliseconds spin period modulation in weak short gamma-ray bursts (GRBs) may
identify them from the archival data. Future MeV detectors can detect them at a
rate from a few to tens per year. The recent report on the
Quasi-Period-Oscillation found in two BASTE GRBs should not be considered as
cases of such flares, for they were detection in a lower energy range and with
a much shorter period spin modulation.Comment: 10 pages, 5 figures, submitted to ApJ
What aspects of the home literacy environment differentiate Chinese children at risk for reading difficulties from their not at risk controls?
We examined what aspects of the home literacy environment (formal home literacy activities, informal home literacy activities, access to literacy resources, age of onset of literacy instruction, childās interest in reading, and parentsā expectations) differentiate Chinese children at risk for reading difficulties from their not-at-risk controls. Eighteen children from Jining, China, who were at risk for reading difficulties and 32 not-at-risk controls participated in the study. Their parents also participated in the study by filling out a home literacy questionnaire, by recording the daily parent-child reading activities (diary), and by completing the Childrenās Title Recognition Checklist. Group comparisons revealed significant differences only in items measuring childrenās access to literacy resources and reading interest. Results of discriminant function analyses further showed that the home literacy environment variables could discriminate well between the children at risk for reading difficulties and their controls. Taken together, our findings suggest that to the extent environment plays a role in reading difficulties in Chinese, this should be traced to factors such as childās interest in reading and access to literacy resources.
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