Sung-Jae Cho

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Coupling the surface state of a topological insulator to an s-wave superconductor is predicted to produce the long-sought Majorana quasiparticle excitations. However, superconductivity has not been measured in surface states when the bulk charge carriers are fully depleted, that is, in the true topological regime relevant for investigating Majorana modes.(More)
Using a macroscopic ensemble of highly enriched (6,5) single-wall carbon nanotubes, combined with high signal-to-noise ratio and time-dependent differential transmission spectroscopy, we have generated vibrational modes in an ultrawide spectral range (10-3000 cm(-1)). A total of 14 modes were clearly resolved and identified, including fundamental modes of(More)
In three-dimensional topological insulators (3D TI) nanowires, transport occurs via gapless surface states where the spin is fixed perpendicular to the momentum 1-6. Carriers encircling the surface thus acquire a π Berry phase, which is predicted to open up a gap in the lowest-energy 1D surface subband. Inserting a magnetic flux (Φ) of h/2e through the(More)
Electron transport through short, phase-coherent metal-graphene-metal devices occurs via resonant transmission through particle-in-a-box-like states defined by the atomically-sharp metal leads. we study the spectrum of particle-in-a-box states for single-and bi-layer graphene, corresponding to massless and massive two-dimensional (2d) Fermions.The density(More)
been proposed as ideal materials for spin conduction 1-7 ; they have long electronic mean free paths 8 and small spin-orbit coupling 9 , hence are expected to have very long spin-scattering times. In addition, spin injection and detection in graphene opens new opportunities to study exotic electronic states such as the quantum Hall 10,11 and quantum spin(More)
Zero-bias anomalies in topological nanowires have recently captured significant attention, as they are possible signatures of Majorana modes. Yet there are many other possible origins of zero-bias peaks in nanowires--for example, weak localization, Andreev bound states, or the Kondo effect. Here, we discuss observations of differential-conductance peaks at(More)
Materials with Dirac electronic spectra (" Dirac materials ") have attracted much interest since the first successful electronic transport measurement in graphene in 2004. Dirac quasiparticles have novel physical properties such as absence of backscattering and Klein tunneling. Topological insulators are a more recently discovered class of materials that(More)
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