Bias driven coherent carrier dynamics in a two-dimensional aperiodic potential |
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Authors: | FABF de Moura ML Lyra F Domínguez-Adame |
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Institution: | a Instituto de Física, Universidade Federal de Alagoas, Maceió AL 57072-970, Brazil b Pólo Penedo, Universidade Federal de Alagoas, Penedo AL 57200-000, Brazil c Centre for Theoretical Physis and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands d GISC, Departamento de Física de Materiales, Universidad Complutense, E-28040 Madrid, Spain |
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Abstract: | We study the dynamics of an electron wave-packet in a two-dimensional square lattice with an aperiodic site potential in the presence of an external uniform electric field. The aperiodicity is described by at lattice sites (mx,my), with πα being a rational number, and νx and νy tunable parameters, controlling the aperiodicity. Using an exact diagonalization procedure and a finite-size scaling analysis, we show that in the weakly aperiodic regime (νx,νy<1), a phase of extended states emerges in the center of the band at zero field giving support to a macroscopic conductivity in the thermodynamic limit. Turning on the field gives rise to Bloch oscillations of the electron wave-packet. The spectral density of these oscillations may display a double peak structure signaling the spatial anisotropy of the potential landscape. The frequency of the oscillations can be understood using a semi-classical approach. |
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Keywords: | 78 30 Ly 71 30 +h 73 20 Jc 72 15 Rn |
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