Anomalous Cyclotron Motion in Graphene Superlattice Cavities

Abstract

We consider graphene superlattice miniband fermions probed by electronic interferometry in magnetotransport experiments. By decoding the observed Fabry-Pérot interference patterns together with our corresponding quantum transport simulations, we find that the Dirac quasiparticles originating from the superlattice minibands do not undergo conventional cyclotron motion but follow more subtle trajectories. In particular, dynamics at low magnetic fields is characterized by peculiar, straight trajectory segments. Our results provide new insights into superlattice miniband fermions and open up novel possibilities to use periodic potentials in electron optics experiments.

Dirac fermion optics and directed emission from single- and bilayer graphene cavities

“…Hexagonal contributions to the Fermi contour E ( k) implies six predominant velocity directions v = k E ( k) as a function of the wave vector k, see Ref. [11]. This allows for the specific realization of patterns with highly focused emission directionality in few directions such as in Fig.…”

“…As a result, the combination of these various special properties, i.e., that charge carriers in graphene partly behave like photons, are deflected by magnetic fields, are reflected or diffracted at p-n junctions and propagate dispersionless, * martina.hentschel@physik.tu-chemnitz.de has opened up the swiftly expanding field of Dirac electron optics based on ultraclean ballistic graphene devices. Correspondingly, optics analogues comprise Klein tunneling in single-layer graphene p-n-p junctions [1][2][3][4][5][6][7], p-n junctions [8][9][10], or Fabry-Pérot type settings [7,11,12] as well as anti-Klein tunneling in bilayer graphene [1,[13][14][15][16][17] where in particular circular p-n junctions were considered [18]. Collimation [8,19], various electron lensing [20][21][22][23], and guiding [24][25][26][27][28][29][30] phenomena were investigated in this context.…”

Dirac fermion optics and directed emission from single- and bilayer graphene cavities

“…particular those for normal incidence) still useful, but at the same time other effects to become important. Figures 9,10,11 display a manifold of internal intensity distributions and mid field emission patterns as source position and asymmetry parameter U are varied. We begin our discussion with a central source position, Fig.…”

“…that charge carriers in graphene partly behave like photons, are deflected by magnetic fields, are reflected or diffracted at p-n junctions and propagate dispersionless, has opened up the swiftly expanding field of Dirac electron optics based on ultraclean ballistic graphene devices. Correspondingly, optics analogues comprise Klein tunneling in singlelayer graphene p-n-p junctions [1][2][3][4][5][6][7] , p-n junctions [8][9][10] , or Fabry-Pérot type settings 7,11,12 as well as anti-Klein tunneling in bilayer graphene 1,[13][14][15][16][17] where in particular circular p-n junktions were considered 18 . Collimation 8,19 , various electron lensing [20][21][22][23] and guiding [24][25][26][27][28][29][30] phenomena were investigated in this context.…”

Fermi Velocity Modulation Induced Low‐Bias Negative Differential Resistance in Graphene Double Barrier Resonant Tunneling diode

“…[ 1,4 ] In this regard, several reports demonstrated how the Fermi velocity alters graphene transport features [ 11–14 ] and its device performance. [ 15,16 ] Among graphene morphologies, quantum wells (QWs), [ 17,18 ] hetrostructures, [ 19–22 ] and superlattices (SLs) [ 23–26 ] have widely been implemented in designing/fabrication emerging devices [ 27–29 ] and exploring novel phenomenon [ 30–35 ] beyond the reach of exciting materials. In this context, resonant tunneling as one of the unique transport processes in SLs exhibited great promise to enrich the potential of SLs and QW devices including tunnel transistors (TFETs) [ 36–38 ] and resonant tunneling diodes (RTDs).…”