11,464 research outputs found
Complexity growth rates for AdS black holes in massive gravity and gravity
The "complexity = action" duality states that the quantum complexity is equal
to the action of the stationary AdS black holes within the Wheeler-DeWitt patch
at late time approximation. We compute the action growth rates of the neutral
and charged black holes in massive gravity and the neutral, charged and
Kerr-Newman black holes in gravity to test this conjecture. Besides, we
investigate the effects of the massive graviton terms, higher derivative terms
and the topology of the black hole horizon on the complexity growth rate.Comment: 11 pages, no figur
Spin Hall effect in spin-valley coupled monolayer transition-metal dichalcogenides
We study both the intrinsic and extrinsic spin Hall effect in spin-valley
coupled monolayers of transition metal dichalcogenides. We find that whereas
the skew-scattering contribution is suppressed by the large band gap, the
side-jump contribution is comparable to the intrinsic one with opposite sign in
the presence of scalar and magnetic scattering. Intervalley scattering tends to
suppress the side-jump contribution due to the loss of coherence. By tuning the
ratio of intra- to intervalley scattering, the spin Hall conductivity shows a
sign change in hole-doped samples. Multiband effect in other doping regime is
considered, and it is found that the sign change exists in the heavily
hole-doped regime, but not in the electron-doped regime
Berry phase modification to the energy spectrum of excitons
By quantizing the semiclassical motion of excitons, we show that the Berry
curvature can cause an energy splitting between exciton states with opposite
angular momentum. This splitting is determined by the Berry curvature flux
through the -space area spanned by the relative motion of the
electron-hole pair in the exciton wave function. Using the gapped
two-dimensional Dirac equation as a model, we show that this splitting can be
understood as an effective spin-orbit coupling effect. In addition, there is
also an energy shift caused by other "relativistic" terms. Our result reveals
the limitation of the venerable hydrogenic model of excitons, and highlights
the importance of the Berry curvature in the effective mass approximation.Comment: 4.5 pages, 2 figures, reference updated and minor change
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