Optical conductivity of single-layer graphene induced by temporal mass-gap fluctuations |
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Authors: | József Zsolt Bernád |
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Institution: | 1. Institut für Angewandte Physik, Technische Universität Darmstadt, D-64289, Germany;2. Institute of Fundamental Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand |
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Abstract: | We consider the dynamics of charge carriers in single-layer graphene that are subject to random temporal fluctuations of their mass gap. The optical conductivity is calculated by incorporating the quantum-stochastic time evolution into the standard linear-response (Kubo) theory. We find that, for an intermediate range of frequencies below the average gap size, electron transport is enhanced by fluctuations. At the same time, in the limit of high as well as low frequencies, the conductivity is suppressed as the variance of gap fluctuations increases. In particular, the dc conductivity is always suppressed by a random temporal mass with nonvanishing mean value and vanishes in the zero-temperature limit. Our results are complementary to those obtained recently for static random-gap disorder in finite-size systems. |
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Keywords: | Graphene Temporal mass-gap fluctuations Quantum-stochastic time evolution Generalized Kubo formula Optical conductivity |
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