arXiv subjects

S. Kubatkin

Publications and source records attributed to S. Kubatkin.

21 records · Page 2Linked to original sources

arXiv2011

Anomalously strong pinning of the filling factor nu=2 in epitaxial graphene

We explore the robust quantization of the Hall resistance in epitaxial graphene grown on Si-terminated SiC. Uniquely to this system, the dominance of quantum over classical capacitance in the charge transfer between the substrate and graphene is such that Landau levels (in particular, the one at exactly zero energy) remain completely filled over an extraordinarily broad range of magnetic fields. One important implication of this pinning of the filling factor is that the system can sustain a very high nondissipative current. This makes epitaxial graphene ideally suited for quantum resistance metrology, and we have achieved a precision of 3 parts in 10^10 in the Hall resistance quantization measurements.

cond-mat.mes-hall↗

arXiv2010

Circular ac Hall Effect

We report the observation of the circular ac Hall effect where the current is solely driven by the crossed ac electric and magnetic fields of circularly polarized radiation. Illuminating an unbiased monolayer sheet of graphene with circularly polarized terahertz radiation at room temperature generates - under oblique incidence - an electric current perpendicular to the plane of incidence, whose sign is reversed by switching the radiation helicity. Alike the classical dc Hall effect, the voltage is caused by crossed electric and magnetic fields which are however rotating with the light's frequency.

cond-mat.mes-hall↗

arXiv2006

An ab initio study of a field-induced position change of a C60 molecule adsorbed on a gold tip

Recent I/V curve measurements suggest that C60 molecules deposited in gold nanojunctions change their adsorption configuration when a finite voltage in a 2-terminal setting is applied. This is of interest for molecular electronics because a robust molecular transistor could be based on such junctions if the mechanism of the process is understood. We present density functional theory based plane wave calculations, where we studied the energetics of the molecule's adsorption under the influence of an external field. Particular emphasis was placed on investigating a possible lightning rod effect which might explain the switching between configurations found in the experiments. We also analyze our results for the adsorption energetics in terms of an electrostatic expression for the total energy, where the dependence of the polarizability of thejunction on the position of the C60 molecule was identified as a crucialproperty for the field induced change of adsorption site.

cond-mat.mtrl-sci↗