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M. Pelc

Publications and source records attributed to M. Pelc.

11 recordsLinked to original sources
arXiv2017

Controlling the layer localization of gapless states in bilayer graphene with a gate voltage

Experiments in gated bilayer graphene with stacking domain walls present topological gapless states protected by no-valley mixing. Here we research these states under gate voltages using atomistic models, which allow us to elucidate their origin. We find that the gate potential controls the layer localization of the two states, which switches non-trivially between layers depending on the applied gate voltage magnitude. We also show how these bilayer gapless states arise from bands of single-layer graphene by analyzing the formation of carbon bonds between layers. Based on this analysis we provide a model Hamiltonian with analytical solutions, which explains the layer localization as a function of the ratio between the applied potential and interlayer hopping. Our results open a route for the manipulation of gapless states in electronic devices, analogous to the proposed writing and reading memories in topological insulators.

cond-mat.mes-hall↗
arXiv2015

Topologically confined states at corrugations of gated bilayer graphene

We investigate the electronic and transport properties of gated bilayer graphene with one corrugated layer, which results in a stacking AB/BA boundary. When a gate voltage is applied to one layer, topologically protected gap states appear at the corrugation, which reveal as robust transport channels along the stacking boundary. With increasing size of the corrugation, more localized, quantum-well-like states emerge. These finite-size states are also conductive along the fold, but in contrast to the stacking boundary states, which are gapless, they present a gap. We have also studied periodic corrugations in bilayer graphene; our findings show that such corrugations between AB- and BA-stacked regions behave as conducting channels that can be easily identified by their shape.

cond-mat.mtrl-sci↗
arXiv2015

Electronic conductance of twisted bilayer nanoribbon flakes

We study the transport properties of a twisted bilayer graphene flake contacted by two monolayer nanoribbons which act as leads. We analyze the conductance in terms of the spectra of the bilayer nanoribbon and the monolayer contacts. The low-energy transport properties are governed by the edge states with AB stacking. Remarkably, the electronic conductance in this energy region does not depend much on the relative position of the leads, in contrast with that of bilayer flakes with more symmetric stackings. We attribute this feature to the localization of these low-energy states in the AB edge regions of the flake, having a much smaller weight at the junctions between the flake and the nanoribbon leads.

cond-mat.mes-hall↗
arXiv2011

Edge states and flat bands in graphene nanoribbons with arbitrary geometries

We prescribe general rules to predict the existence of edge states and zero-energy flat bands in graphene nanoribbons and graphene edges of arbitrary shape. No calculations are needed. For the so-called {\it{minimal}} edges, the projection of the edge translation vector into the zigzag direction of graphene uniquely determines the edge bands. By adding extra nodes to minimal edges, arbitrary modified edges can be obtained. The edge bands of modified graphene edges can be found by applying hybridization rules of the extra atoms with the ones belonging to the original edge. Our prescription correctly predicts the localization and degeneracy of the zero-energy bands at one of the graphene sublattices, confirmed by tight-binding and first-principle calculations. It also allows us to qualitatively predict the existence of $E\ne 0$ bands appearing in the energy gap of certain edges and nanoribbons.

cond-mat.mes-hall↗
arXiv2009

Interface States in Carbon Nanotube Junctions: Rolling up graphene

We study the origin of interface states in carbon nanotube intramolecular junctions between achiral tubes. By applying the Born-von Karman boundary condition to an interface between armchair- and zigzag-terminated graphene layers, we are able to explain their number and energies. We show that these interface states, costumarily attributed to the presence of topological defects, are actually related to zigzag edge states, as those of graphene zigzag nanoribbons. Spatial localization of interface states is seen to vary greatly, and may extend appreciably into either side of the junction. Our results give an alternative explanation to the unusual decay length measured for interface states of semiconductor nanotube junctions, and could be further tested by local probe spectroscopies.

cond-mat.mes-hall↗
arXiv2009

Attoheat transport phenomena

Fascinating developments in optical pulse engineering over the last 20 years lead to the generation of laser pulses as short as few femtosecond, providing a unique tool for high resolution time domain spectroscopy. However, a number of the processes in nature evolve with characteristic times of the order of 1 fs or even shorter. Time domain studies of such processes require at first place sub-fs resolution, offered by pulse depicting attosecond localization. The generation, characterization and proof of principle applications of such pulses is the target of the attoscience. In the paper the thermal processes on the attosecond scale are described. The Klein-Gordon and Proca equations are developed. The relativistic effects in the heat transport on nanoscale are discussed. It is shown that the standard Fourier equation can not be valid for the transport phenomena induced by attosecond laser pulses. The heat transport in nanoparticles and nanotubules is investigated.

physics.gen-ph↗
arXiv2007

Universal relaxation times for electron and nucleon gases

In this paper we calculate the universal relaxation times for electron and nucleon fermionic gases. We argue that the universal relaxation time tau(i) is equal tau(i)=h/m square v(i) where v(i)=alpha(i)c and alpha(1)=0.15 for nucleon gas and alpha(2)=1/137 for electron gas, c=light velocity. With the universal relaxation time we formulate the thermal Proca equation for fermionic gases. Key words: universal relaxation time, thermal universal Proca equation.

physics.gen-ph↗
arXiv2007

On the temperature of the moving rod

In this paper the Lorentz transformation for temperature is derived and discussed. Considering the hyperbolic heat transport equation it is shown that T(prim) = gamma T, where gamma is the Lorentz factor, T denotes the temperature in the rest system and T(prim) is the temperature in the moving system (rod).

physics.gen-ph↗
arXiv2007

The modified Klein Gordon equation for neolithic population migration

In this paper the model for the neolithic migration in Europe is developed. The new migration equation, the modified Klein Gordon equation is formulated and solved. It is shown that the migration process can be described as the hyperbolic diffusion with constant speed. In comparison to the existing models based on the generalization of the Fisher approach the present model describes the migration as the transport process with memory and offers the possibility to recover the initial state of migration which is the wave motion with finite velocity.

physics.gen-ph↗
arXiv2005

Heisenberg uncertainty principle for thermal response of the microtubules excited by ultra-short laser pulses

In this paper the heat signaling in microtubules (MT) is investigated. It is argued that for the description of the heat signaling phenomena in MT, the hyperbolic heat transport (HHT) equation must be used. It is shown that HHT is the Klein-Gordon (K-G) equation. The general solution for the K-G equation for MT is obtained. For the undistorted signal propagation in MT the Heisenberg uncertainty principle is formulated and discussed. Key words: Microtubules; Heat signaling; Klein-Gordon equation; Heisenberg principle.

q-bio.BM↗