There has been growing research interest in realizing optoelectronic devices based on the two-dimensional atomically thin semiconductor MoS2 owing to its distinct physical properties that set it apart from conventional semiconductors. However, there is little optical absorption in these extremely thin MoS2 layers, which presents an obstacle toward applying them for use in high-efficiency light-absorbing devices. We synthesized trilayers of MoS2 directly on SiO2/Si nanocone (NC) arrays using chemical vapor deposition and investigated their photodetection characteristics.

In this work we study the effect of static disorder on the growth of commutators - a probe of information scrambling in quantum many-body systems - in a variety of contexts. We find generically that disorder slows the onset of scrambling and, in the case of a many-body localized (MBL) state, partially halts it. In the MBL state, we show using a fixed point Hamiltonian that operators exhibit slow logarithmic growth under time evolution and compare the result with the expected growth of commutators in (de)localized noninteracting disordered models.

We report an initial experimental survey of spin Hall torques generated by the rare-earth metals Gd, Dy, Ho, and Lu, along with comparisons to first-principles calculations of their spin Hall conductivities. Using spin torque ferromagnetic resonance (ST-FMR) measurements and dc-biased ST-FMR, we estimate lower bounds for the spin Hall torque ratio, ξSH, of ≈0.04 for Gd, ≈0.05 for Dy, ≈0.14 for Ho, and ≈0.014 for Lu.

Broken fourfold rotational (C4) symmetry is observed in the experimental properties of several classes of unconventional superconductors. It has been proposed that this symmetry breaking is important for superconducting pairing in these materials, but in the high-Tc cuprates this broken symmetry has never been observed on the Fermi surface. Here we report a pronounced anisotropy in the angle dependence of the interlayer magnetoresistance of the underdoped high transition temperature (high-Tc) superconductor YBa2Cu3O6.58, directly revealing broken C4 symmetry on the Fermi surface.

We study the electronic band structure in the K/K′ valleys of the Brillouin zone of monolayer WSe2 and MoSe2 by optical reflection and photoluminescence spectroscopy on dual-gated field-effect devices. Our experiment reveals the distinct spin polarization in the conduction bands of these compounds by a systematic study of the doping dependence of the A and B excitonic resonances. Electrons in the highest-energy valence band and the lowest-energy conduction band have antiparallel spins in monolayer WSe2 and parallel spins in monolayer MoSe2.

A Raman spectroscopy study was carried out on ZnGeN2 hexagonal single crystal (0001)-oriented platelets obtained by reaction of gaseous ammonia with a Zn-Ge-Sn liquid alloy at 758 °C. The sample geometry allowed measurement of the A2 and A1 Raman modes. First-principles calculations of the spectra were carried out using an improved pseudopotential. Measurements with crossed polarizers yielded spectra that agreed well with first-principles calculations of the A2 modes. Measurements with parallel polarizers should in principle provide the A1L modes.

As a solid body approaches a wall in a viscous fluid, the flow in the gap between them is dominated by the viscous effect and can be approximated by the lubrication theory. Here we show that without gravity, a cylinder comes to rest asymptotically at a finite separation from the wall, whereas with gravity, the cylinder approaches the wall asymptotically and contact does not happen in finite time. A cylinder approaches the wall much slower compared to a sphere under matching conditions, implying that the lubrication approximates hold longer before the molecular scale sets in.

Electrons in monolayer transition metal dichalcogenides are characterized by valley and spin quantum degrees of freedom, making it possible to explore new physical phenomena and to foresee novel applications in the fields of electronics and optoelectronics. Theoretical proposals further suggest that Berry curvature effects, together with strong spin-orbit interactions, can generate unconventional Landau levels (LLs) under a perpendicular magnetic field. In particular, these would support valley- and spin-polarized chiral edge states in the quantum Hall regime.

We calculate the topological part of the electromagnetic response of bosonic integer quantum Hall (BIQH) phases in odd (space-time) dimensions, and bosonic topological insulator (BTI) and bosonic chiral semimetal (BCSM) phases in even dimensions. To do this, we use the nonlinear sigma model (NLSM) description of bosonic symmetry-protected topological (SPT) phases, and the method of gauged Wess-Zumino (WZ) actions.

Upconversion is a unique optical property that is driven by a sequential photon pumping and generation of higher energy photons in a consecutive manner. The efficiency improvement in photovoltaic devices can be achieved when upconverters are integrated since upconverters contribute to the generation of extra photons. Despite numerous experimental studies confirming the relationship, fundamental explanations for a real contribution of upconversion to photovoltaic efficiency are still in demand.