arXiv subjects

K. Kechedzhi

Publications and source records attributed to K. Kechedzhi.

23 records · Page 2Linked to original sources

arXiv2009

Mesoscopic conductance fluctuations in graphene

We study fluctuations of the conductance of micron-sized graphene devices as a function of the Fermi energy and magnetic field. The fluctuations are studied in combination with analysis of weak localization which is determined by the same scattering mechanisms. It is shown that the variance of conductance fluctuations depends not only on inelastic scattering that controls dephasing but also on elastic scattering. In particular, contrary to its effect on weak localization, strong intervalley scattering suppresses conductance fluctuations in graphene. The correlation energy, however, is independent of the details of elastic scattering and can be used to determine the electron temperature of graphene structures.

cond-mat.mes-hall↗

arXiv2009

Quantum transport thermometry for electrons in graphene

We propose a method of measuring the electron temperature $T_e$ in mesoscopic conductors and demonstrate experimentally its applicability to micron-size graphene devices in the linear-response regime ($T_e\approx T$, the bath temperature). The method can be {especially useful} in case of overheating, $T_e>T$. It is based on analysis of the correlation function of mesoscopic conductance fluctuations. Although the fluctuation amplitude strongly depends on the details of electron scattering in graphene, we show that $T_e$ extracted from the correlation function is insensitive to these details.

cond-mat.mes-hall↗

arXiv2008

Quantum kinetic equation and universal conductance fluctuations in graphene

We analyze universal conductance fluctuations (UCF) in graphene in the framework of diagrammatic perturbation theory in the metallic regime. It is shown that strong inter-valley scattering lifts the valley degeneracy of electronic states, whereas at weak inter-valley scattering two valleys contribute independently such that the variance of UCF would be expected to show sample- and geometry-dependent behavior.

cond-mat.mes-hall↗

arXiv2007

Influence of trigonal warping on interference effects in bilayer graphene

Bilayer graphene (two coupled graphitic monolayers arranged according to Bernal stacking) is a two-dimensional gapless semiconductor with a peculiar electronic spectrum different from the Dirac spectrum in the monolayer material. In particular, the electronic Fermi line in each of its valleys has a strong p -> -p asymmetry due to a trigonal warping, which suppresses the weak localization effect. We show that weak localisation in bilayer graphene may be present only in devices with pronounced intervalley scattering, and we evaluate the corresponding magnetoresistance.

cond-mat.mes-hall↗

arXiv2006

Weak localisation magnetoresistance and valley symmetry in graphene

Due to the chiral nature of electrons in a monolayer of graphite (graphene) one can expect weak antilocalisation and a positive weak-field magnetoresistance in it. However, trigonal warping (which breaks p/-p symmetry of the Fermi line in each valley) suppresses antilocalisation, while inter-valley scattering due to atomically sharp scatterers in a realistic graphene sheet or by edges in a narrow wire tends to restore conventional negative magnetoresistance. We show this by evaluating the dependence of the magnetoresistance of graphene on relaxation rates associated with various possible ways of breaking a 'hidden' valley symmetry of the system.

cond-mat.mes-hall↗