Noise reveals nanosecond dynamics in V2O3
Noise measurements shows fluctuations in the resistance of V2O3 at timescales down to fractions of a nanosecond during the metal-insulator transition. These observations are consistent with "p-noise", a model of percolation. This work, led by Liyang Chen, was reported in APL Materials..
Photothermoelectric response of single-crystal Au
Measuring the photothermoelectric response of single-crystal and bi-crystal gold wires reveals surprises. Sharp, high-angle grain boundaries have almost no effect, while subtle structural defects are readily detectable by this impressively sensitive technique. This work, led by Charlotte Evans, was reported in Proc. Nat. Acad. Sci. US.
Plasmon-enhanced hot carrier electroluminescence
Electrically driven plasmonic tunnel junctions are found to emit light at energies well above the applied voltage scale. This result shows that plasmons play a previously unappreciated role in the efficient generation of non-equilibrium electrons with very high effective temperatures. This work, led by Dr. Longji Cui, was reported in Nano Lett..
Tunneling noise reveals pairing in cuprates
Measuring shot noise can reveal the magnitude of the effective charge of carriers. Shot shot noise in La2-xSrxCuO4/La2CuO4/La2-xSrxCuO4 tunnel junctions is enhanced above the single-charge expectation at temperatures and voltages above the supeconducting scale, implying pairing of carriers at energies without superconductivity. This work, led by Panpan Zhou, was reported in Nature..
Remote excitation of hot electrons
Gratings allow light to excite propagating surface plasmon polariton (SPP) modes. When these SPPs reach a tunneling nanogap, they can induce hot electron tunneling, detected via open-circuit voltage. Local junction symmetry matters, as SPPs propagating in one direction can lead to hot electrons flowing the opposite direction. This work, led by Charlotte Evans, was reported in J. Phys. Chem. C..
Electrical detection of propagating plasmons
We can detect propagating surface plasmon polaritons (SPPs) electrically throught their heating of the metal. Remotely launching these SPPs gets optical energy to a nanoscale constriction while minimizing the local temperature increase (by 60x compared to direct illumination of the constriction). This work, led by Ms. Charlotte Evans, was reported in Nano Lett..
Large photovoltages in nanogaps
Tunneling of hot electrons generated by plasmon-enhanced optical absorption can lead to comparatively large photovoltages in metal nanogaps. This work, led by Dr. Pavlo Zolotavin was reported in J. Phys. Chem. Lett., and highlighted in a news release. Click here to see a LiveSlides presentation about the work.
Surprising voltage fluctuations
Will Hardy et al. discovered some unusual low-frequency voltage fluctuations in strontium titanate quantum wells. These fluctuations grow as temperature is decreased, even in the absence of a driving current. We posit that they come from etching-related fluctuating defects modulating the local thermoelectric properties of the material.
Shot noise in hBN tunnel junctions
Panpan Zhou et al. have demonstrated through shot noise measurements that atomically thin hexagonal boron nitride (hBN) is an excellent tunnel barrier. This opens up the possibility of using hBN to enable tunneling noise spectroscopy on a variety of complex materials.