22,813 research outputs found
Super-resolution image transfer by a vortex-like metamaterial
We propose a vortex-like metamaterial device that is capable of transferring
image along a spiral route without losing subwavelength information of the
image. The super-resolution image can be guided and magnified at the same time
with one single design. Our design may provide insights in manipulating
super-resolution image in a more flexible manner. Examples are given and
illustrated with numerical simulations.Comment: 7 pages, 6 figure
Coherent control of high-harmonic generation using waveform-synthesized chirped laser fields
We show that waveform-synthesized chirped laser fields are efficient tools for coherent harmonic control. A single harmonic order, or two harmonic orders, can be selectively enhanced by using a two-color field allowing a moderate linear chirp for each color. Different harmonic orders within a wide spectral range can be selectively enhanced by adjusting the laser parameters. Our theory bridges two current harmonic control techniques, namely, single-color phase shaping and multicolor amplitude synthesis, and opens the door to new harmonic control possibilities
Loop-current charge density wave driven by long-range Coulomb repulsion on the kagome lattice
Recent experiments on vanadium-based nonmagnetic kagom\'e metals
VSb ( K, Rb, Cs) revealed evidence for possible spontaneous
time-reversal symmetry (TRS) breaking in the charge density wave (CDW) ordered
state. The long-sought-after quantum order of loop currents has been suggested
as a candidate for the TRS breaking state. However, a microscopic model for the
emergence of the loop-current CDW due to electronic correlations is still
lacking. Here, we calculate the susceptibility of the real and imaginary bond
orders on the kagom\'e lattice near van Hove filling, and reveal the importance
of next-nearest-neighbor Coulomb repulsion in triggering the instability
toward imaginary bond ordered CDW. The concrete effective single-orbital
-- model on the kagom\'e lattice is then studied, where and
are the hopping and Coulomb repulsion on the nearest-neighbor bonds. We
obtain the mean-field ground states, analyze their properties, and determine
the phase diagram in the plane spanned by and at van Hove filling.
The region dominated by is occupied by a real CDW
insulator with the inverse of Star-of-David (ISD) bond configuration.
Increasing indeed drives a first-order transition from the ISD to
stabilized loop-current insulators that exhibit four possible current patterns
of different topological properties, leading to orbital Chern insulators. We
then extend these results away from van Hove filling and show that the
loop-current states survive in the lightly doped orbital Chern insulators, and
give rise to emergent Chern Fermi pockets carrying large Berry curvature and
orbit magnetic moment. Our findings provide a concrete model realization of the
loop-current Chern metal at the mean-field level for the TRS breaking normal
state of the kagom\'e superconductors.Comment: 11 pages, 6 figure
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