A5029150022- Topological Materials and Phenomena
- Graphene research and applications
- Quantum and electron transport phenomena
- 2D Materials and Applications
- Physics of Superconductivity and Magnetism
- Iron-based superconductors research
- Advanced Condensed Matter Physics
- Semiconductor Quantum Structures and Devices
- Diamond and Carbon-based Materials Research
- Muon and positron interactions and applications
- Plasmonic and Surface Plasmon Research
- Magnetic properties of thin films
- Aerogels and thermal insulation
- Quantum Dots Synthesis And Properties
- Surface and Thin Film Phenomena
- Advanced Fiber Laser Technologies
- Molecular Junctions and Nanostructures
- Photorefractive and Nonlinear Optics
- Magnetic and transport properties of perovskites and related materials
- Phase-change materials and chalcogenides
- Nonlinear Photonic Systems
- Nonlinear Waves and Solitons
- Advanced biosensing and bioanalysis techniques
- Perovskite Materials and Applications
- Advanced Thermoelectric Materials and Devices
Hebrew University of Jerusalem
2015-2025
Massachusetts Institute of Technology
2010-2015
Klinik und Poliklinik für Psychiatrie und Psychotherapie
2002-2010
Weizmann Institute of Science
2004-2010
University Hospital Leipzig
2010
Center for NanoScience
2010
Harvard University
2005
Leipzig University
2004
The unique electronic properties of the surface electrons in a topological insulator are protected by time-reversal symmetry. Circularly polarized light naturally breaks symmetry, which may lead to an exotic quantum Hall state. Using time- and angle-resolved photoemission spectroscopy, we show that intense ultrashort mid-infrared pulse with energy below bulk band gap hybridizes Dirac fermions form Floquet-Bloch bands. These photon dressed bands exhibit polarization-dependent gaps at avoided...
We report on measurements of quantum many-body modes in ballistic wires and their dependence Coulomb interactions, obtained by tunneling between two parallel an GaAs/AlGaAs heterostructure while varying electron density. observed spin one charge mode the coupled mapped dispersion velocities down to a critical density, at which spontaneous localization was observed. Theoretical calculations velocity agree well with data, although they also predict additional that not The measured smaller than...
We study coherent electronic transport in charge-density-tunable microdevices patterned from thin films of the topological insulator (TI) Bi${}_{2}$Se${}_{3}$. The devices exhibit pronounced electric field effect, including ambipolar modulation resistance with an on-and-off ratio 500%. show that weak antilocalization correction to conductance is sensitive number coherently coupled channels, which a TI includes top and bottom surfaces bulk carriers. These are separated into independent...
An exchange gap in the Dirac surface states of a topological insulator (TI) is necessary for observing predicted unique features such as magnetoelectric effect well to confine Majorana fermions. We experimentally demonstrate proximity-induced ferromagnetism TI, combining ferromagnetic EuS layer with ${\mathrm{Bi}}_{2}{\mathrm{Se}}_{3}$, without introducing defects. By magnetic and magnetotransport studies, including anomalous Hall magnetoresistance measurements, we show emergence phase step...
Electronic transport experiments involving the topologically protected states found at surface of Bi2Se3 and other topological insulators require fine control over carrier density, which is challenging with existing bulk-doped material. Here we report on electronic measurements thin (<100 nm) devices show that density can be modulated via electric field effect by using a top-gate high-k dielectric insulator. The conductance dependence geometry, gate voltage, temperature all indicate governed...
We perform time- and angle-resolved photoemission spectroscopy of a prototypical topological insulator (TI) Bi(2)Se(3) to study the ultrafast dynamics surface bulk electrons after photoexcitation. By analyzing evolution states band spectra, we obtain their electronic temperature chemical potential relaxation separately. These reveal strong phonon-assisted surface-bulk coupling at high lattice total suppression inelastic scattering between low temperature. In this regime, unique cooling Dirac...
We study experimentally and theoretically the interactions among ultrashort optical pulses in soliton rain multiple-pulse dynamics of a fiber laser. The laser is mode locked by graphene saturable absorber fabricated using mechanical transfer technique. Dissipative solitons aggregate into pulse bunches that exhibit complex behavior, which includes acceleration bidirectional motion moving reference frame. drift speed direction depend on bunch size relative location cavity, punctuated abrupt...
Tunnel junctions, a well-established platform for high-resolution spectroscopy of superconductors, require defect-free insulating barriers with clean engagement to metals on both sides. Extending the range materials accessible tunnel junction fabrication, beyond limited selection which allows high-quality oxide formation, requires development alternative fabrication techniques. Here we show that van-der-Waals (vdW) barriers, fabricated by stacking layered semiconductors top transition metal...
Fiber lasers are convenient for studying extreme and rare events, such as rogue waves, thanks to the lasers' fast dynamics.Indeed, several types of wave patterns were observed in fiber at different time-scales: single peak, twin triple peak.We measured statistics these ultrafast with a time lens developed numerical model proving that waves generated by non-instantaneous relaxation saturable absorber together polarization mode dispersion cavity.Our results indicate dynamics is directly...
The unique electronic properties of the surface electrons in a topological insulator [1] are protected by time-reversal symmetry. Circularly polarized light naturally breaks symmetry, which may lead to an exotic quantum Hall state [2]. Using time- and angle-resolved photoemission spectroscopy [3] [4], we show that intense ultrashort mid-infrared pulse with energy below bulk band gap hybridizes Dirac fermions form Floquet-Bloch bands when pump is present [Fig. 1] [5]. These photon dressed...
Hybrid ferromagnetic/superconducting systems are well-known for hosting intriguing phenomena such as emergent triplet superconductivity at their interfaces and the appearance of in-gap, spin-polarized Yu-Shiba-Rusinov (YSR) states bound to magnetic impurities on a superconducting surface. In this work we demonstrate that similar can be induced surface conventional superconductor by chemisorbing nonmagnetic chiral molecules. Conductance spectra measured NbSe2 flakes over which α-helix...
Equal spin triplet pairs (ESTPs) of nuclei form the ground state superfluid ${}^{3}$He. ESTPs electrons have long been sought in superconducting systems. In layered transition metal dichalcogenides with 2$H$ structure, such as NbSe${}_{2}$, ESTP correlations predicted to arise from interaction Ising spin-orbit field, which pins internal axis conventional singlet out-of-plane, and an applied in-plane magnetic field. The tunneling spectroscopy study done here bilayer NbSe${}_{2}$ shows...
The many-body wave function of localized states in one dimension is probed by measuring the tunneling conductance between two parallel wires, fabricated a $\mathrm{Ga}\mathrm{As}∕\mathrm{Al}\mathrm{Ga}\mathrm{As}$ heterostructure. Tunneling presence magnetic field perpendicular to plane wires serves as probe momentum space wires. One driven into regime using density tuning gate, whereas other wire, still extended electronic states, spectrometer. As electron lowered critical value, state at...
We determine the zero temeperature phase diagram of excitons in symmetric transition-metal dichalcogenide tri-layer heterosctructure WSe2/MoSe2/WSe2. First principle calculations reveal two distinct types interlayer excitonic states, a lower energy quadrupole and higher asymmetric dipole. While interaction between quadrupolar is always repulsive, anti-parallel dipolar attract at large distances. find quantum transitions repulsive lattice staggered (anti-parallel) phase, driven by competition...
CrGeTe3 (CGT) is a semiconducting vdW ferromagnet shown to possess magnetism down two-layer thick sample. Although CGT one of the leading candidates for spintronics devices, comprehensive analysis thickness dependent magnetization currently lacking. In this work, we employ scanning SQUID-on-tip (SOT) microscopy resolve magnetic properties exfoliated flakes at 4.2 K. Combining transport measurements CGT/NbSe2 samples with SOT images, present texture and hysteretic CGT, thereby matching global...
As performance of van der Waals heterostructure devices is governed by the nanoscale thicknesses and homogeneity their constituent mono- to few-layer flakes, accurate mapping these properties with high lateral resolution becomes imperative. Spectroscopic ellipsometry a promising optical technique for such atomically thin-film characterization due its simplicity, noninvasive nature accuracy. However, effective use standard methods on exfoliated micron-scale flakes inhibited tens-of-microns or...
Abstract The coexistence of multiple types orders is a common thread in condensed matter physics and unconventional superconductors. nature superconducting may be unveiled by analyzing local perturbations such as vortices. For thin films, the vortex magnetic profile characterized Pearl-length $$\Lambda$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>Λ</mml:mi> </mml:math> , which inversely proportional to 2D superfluid density; hence, normally, also film thickness, $$d$$...
MXenes have attracted significant attention in recent years due to their exceptional properties for electrochemical and optoelectronic applications. While the physical of MXene thin films, consisting stacked delaminated flakes, been extensively studied, intrinsic can only be derived from individual flakes. Indeed, flake interconnectivity, intercalated species, film morphology introduce extrinsic factors that affect charge transport optical properties. In this work, we quantitatively...
We report on electronic transport measurements of dual-gated nanodevices the low-carrier density topological insulator (TI) Bi_{1.5}Sb_{0.5}Te_{1.7}Se_{1.3}. In all devices, upper and lower surface states are independently tunable to Dirac point by top bottom gate electrodes. thin electric fields found penetrate through bulk, indicating finite capacitive coupling between states. A charging model allows us use penetrating field as a measurement intersurface capacitance C_{TI} state...