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The advent of few-layer graphene has given rise to a new family of two-dimensional systems with emergent electronic properties governed by relativistic quantum mechanics. The multiple carbon sublattices endow the electronic wavefunctions with pseudospin, a lattice analogue of the relativistic electron spin, whereas the multilayer structure leads to electric-field-effect tunable electronic bands. Here we use these properties to realize giant conductance oscillations in ballistic trilayer graphene Fabry-Pérot interferometers, which result from phase coherent transport through resonant bound states beneath an electrostatic barrier. We confine these states by selectively decoupling them from the leads, resulting in transport via non-resonant states and suppression of the giant oscillations. The confinement is achieved both classically, by manipulating quasiparticle momenta with a magnetic field, and quantum mechanically, by locally varying the pseudospin character of the carrier wavefunctions. Our results illustrate the unique potential of trilayer graphene as a versatile platform for electron optics and pseudospintronics.

We report on magnetotransport studies of dual-gated, Bernal-stacked trilayer graphene (TLG) encapsulated in boron nitride crystals. We observe a quantum Hall effect staircase which indicates a complete lifting of the 12-fold degeneracy of the zeroth Landau level. As a function of perpendicular electric field, our data exhibit a sequence of phase transitions between all integer quantum Hall states in the filling factor interval −8 < ν < 0. We develop a theoretical model and argue that, in contrast to monolayer and bilayer graphene, the observed Landau level splittings and quantum Hall phase transitions can be understood within a single-particle picture, but imply the presence of a charge density imbalance between the inner and outer layers of TLG, even at charge neutrality and zero transverse electric field. Our results indicate the importance of a previously unaccounted band structure parameter which, together with a more accurate estimate of the other tight-binding parameters, results in a significantly improved determination of the electronic and Landau level structure of TLG. DOI: 10.1103/PhysRevLett.117.066601 The electronic properties of ABA-stacked trilayer graphene (TLG) are being intensively investigated [1-6] due to its distinct band structure which consists of two overlapping monolayer-graphene-like (MLG-like) and bilayergraphene-like (BLG-like) bands [1,[7][8][9][10][11][12][13][14]. However, in contrast to MLG and BLG, which are gapless, both subbands in ABA-stacked TLG are gapped, with small masses of the order of a few meV.One of the most interesting characteristics of ABAstacked TLG compared to other graphene systems is the way in which its band structure is modified by a perpendicular electric field [2,12,[14][15][16][17][18]. Theory predicts that a weak electric field hybridizes the MLG-like and BLG-like bands, rather than inducing a band gap, as in BLG or ABC-stacked TLG [3,16,[19][20][21]. The hybridized bands are characterized by a strong trigonal warping. For very strong electric fields, a new set of Dirac points was theoretically predicted, with masses and velocities that are controlled by the electric field [18,22]. Thus biased TLG can potentially provide an opportunity to study chiral carriers with tunable anisotropic dispersion, different symmetry, and higher valley degeneracy (6 as opposed to two in MLG and BLG), not accessible in MLG and BLG.Here we report on transport studies of high-mobility TLG samples in the quantum Hall effect regime. We fabricated dual-gated TLG samples encapsulated in hexagonal boron nitride [23,24] crystals (hBN) [Figs. 1(a)-1(b)], which allowed us to independently control the carrier density n and perpendicular electric displacement field D. We use magnetotransport measurements to study how Landau levels (LLs) evolve under D. By inspecting the pattern of LL crossings resulting from the hybridization of the BLG-like and MLG-like bands as a function of n, D, and magnetic field B, we are able to refine the values of the TLG band structure parameters.Additional...

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Progress in satellite technologies is ongoing and eventually finds applications back on Earth. Electric propulsion systems have been proven effective on large scale satellites (NASA DAWN) with better propellant efficiency than chemical or cold gas propulsion, and if miniaturized can be promising for long term operation of nano-satellites (e.g., CubeSats) in low Earth orbit or in deep space (NASA MarCO). However, the power supplies often used to power these electric thrusters, particularly those involving radiofrequency (RF) plasma, typically comprise power inefficient linear mode RF power amplifiers (e.g., class AB). These are simple systems designed to operate reliably under a wide range of loads for versatility, but they suffer low power efficiencies when operating at conditions significantly different from the nominal operating point. The required bulky and heavy thermal management components deem these electric propulsion systems impossible to fit on board nano-satellites. Here we present a compact and efficient switched mode dc-RF power inverter integrated with an electro-thermal plasma micro-thruster for nano-satellite (e.g., Cubesats) propulsion. The integrated system can serve as side panels and structural support of CubeSats, saving precious on-board volume for propellant and/or payloads. A complete assembly has been operationally tested in a space simulation system. This development opens a route for a new generation of power supplies applicable to the space sector, the microelectronics industry as well as the field of bioengineering.