Reconfigurable memlogic long wave infrared sensing with superconductors

Optical sensors with in-cell logic and memory capabilities offer new horizons in realizing machine vision beyond von Neumann architectures and have been attempted with two-dimensional materials,memristive oxides,phasechanging materials etc.Noting the unparalleled performance of superconductors with both quantum-limited optical sensitivities and ultra-wide spectrum coverage,here we report a superconducting memlogic long-wave infrared sensor based on the bistability in hysteretic superconductor-normal phase transition.Driven cooperatively by electrical and optical pulses,the device offers deterministic in-sensor switching between resistive and superconducting(hence dissipationless)states with persistence>105 s.This results in a resilient reconfigurable memlogic system applicable for,e.g.,encrypted communications.Besides,a high infrared sensitivity at 12.2μm is achieved through its in-situ metamaterial perfect absorber design.Our work opens the avenue to realize all-in-one superconducting memlogic sensors,surpassing biological retina capabilities in both sensitivity and wavelength,and presents a groundbreaking opportunity to integrate visional perception capabilities into superconductor-based intelligent quantum machines.

Molecular beam epitaxy of superconducting PdTe_2 films on topological insulator Bi_2Te_3

Majorana fermions have been observed in topological insulator/s-wave superconductor heterostructures. To manipulate Majorana fermions, superconducting materials should be deposited on the surfaces of topological insulators. In this study, highquality superconducting PdTe_2 films are deposited on the topological insulator Bi_2Te_3 surface using molecular beam epitaxy. The surface topography and electronic properties of PdTe_2/Bi_2Te_3 heterostructures are investigated via in situ scanning tunneling microscopy/spectroscopy. Under Te-rich conditions, the Pd atoms presumably form PdTe_2 film on Bi_2Te_3 surface rather than diffuse into Bi_2Te_3. The superconductivity of the PdTe_2/Bi_2Te_3 heterostructure is detected at a transition temperature of ～1.4 K using the two-coil mutual inductance technique. This study proposes a method for fabricating superconducting materials on topological insulator surfaces at low doping levels, paving ways for designing nanodevices that can manipulate Majorana fermions.

Progress of microscopic thermoelectric effects studied by micro- and nano-thermometric techniques

Heat dissipation is one of the most serious problems in modern integrated electronics with the continuously decreasing devices size. Large portion of the consumed power is inevitably dissipated inthe form of waste heat which not only restricts the device energy-efficiency performance itself, butalso leads to severe environment problems and energy crisis. Thermoelectric Seebeck effect is a greenenergy-recycling method, while thermoelectric Peltier effect can be employed for heat management byactively cooling overheated devices, where passive cooling by heat conduction is not sufficiently enough.However, the technological applications of thermoelectricity are limited so far by their very low conversion efficiencies and lack of deep understanding of thermoelectricity in microscopic levels. Probingand managing the thermoelectricity is therefore fundamentally important particularly in nanoscale. Inthis short review, we will first briefly introduce the microscopic techniques for studying nanoscale thermoelectricity, focusing mainly on scanning thermal microscopy (SThM). SThM is a powerful tool formapping the lattice heat with nanometer spatial resolution and hence detecting the nanoscale thermaltransport and dissipation processes. Then we will review recent experiments utilizing these techniques to investigate thermoelectricity in various nanomaterial systems including both (two-material)heterojunctions and (single-material) homojunctions with tailored Seebeck coefficients, and also spinSeebeck and Peltier effects in magnetic materials. Next, we will provide a perspective on the promisingapplications of our recently developed Scanning Noise Microscope (SNoiM) for directly probing thenon-equilibrium transporting hot charges (instead of lattice heat) in thermoelectric devices. SNoiMtogether with SThM are expected to be able to provide more complete and comprehensive understanding to the microscopic mechanisms in thermoelectrics. Finally, we make a conclusion and outlook onthe future development of microscopic studies in thermoelectrics.