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Owing to their atomic-scale thickness, the resonances of two-dimensional (2D) material membranes show signatures of nonlinearities at forces of only a few picoNewtons. Although the linear dynamics of membranes is well understood, the exact relation between the nonlinear response and the resonator’s material properties has remained elusive. Here we show a method for determining the Young’s modulus of suspended 2D material membranes from their nonlinear dynamic response. To demonstrate the method, we perform measurements on graphene and MoS2 nanodrums electrostatically driven into the nonlinear regime at multiple driving forces. We show that a set of frequency response curves can be fitted using only the cubic spring constant as a fit parameter, which we then relate to the Young’s modulus of the material using membrane theory. The presented method is fast, contactless, and provides a platform for high-frequency characterization of the mechanical properties of 2D materials. [ABSTRACT FROM AUTHOR]

Superconducting quantum interference devices (SQUIDs) are the most sensitive detectors of magnetic flux and are also used as quantum two-level systems (qubits). Recent proposals have explored a novel class of devices that incorporate micromechanical resonators into SQUIDs to achieve controlled entanglement of the resonator ground state and a qubit as well as permitting cooling and squeezing of the resonator modes and enabling quantum-limited position detection. In spite of these intriguing possibilities, no experimental realization of an on-chip, coupled mechanical-resonator–SQUID system has yet been achieved. Here, we demonstrate sensitive detection of the position of a 2 MHz flexural resonator that is embedded into the loop of a d.c. SQUID. We measure the resonator’s thermal motion at millikelvin temperatures, achieving an amplifier-limited displacement sensitivity of 10 fm Hz−1/2 and a position resolution that is 36 times the quantum limit. [ABSTRACT FROM AUTHOR]

Porous, atomically thin graphene membranes have interesting properties for filtration and sieving applications. Here, graphene membranes are used to pump gases through nanopores using optothermal forces, enabling the study of gas flow through nanopores at frequencies above 100 kHz. At these frequencies, the motion of graphene is closely linked to the dynamic gas flow through the nanopore and can thus be used to study gas permeation at the nanoscale. By monitoring the time delay between the actuation force and the membrane mechanical motion, the permeation time-constants of various gases through pores with diameters from 10–400 nm are shown to be significantly different. Thus, a method is presented for differentiating gases based on their molecular mass and for studying gas flow mechanisms. The presented microscopic effusion-based gas sensing methodology provides a nanomechanical alternative for large-scale mass-spectrometry and optical spectrometry based gas characterisation methods. Atomically thin porous graphene is promising for filtration and sieving applications. Here the authors, using a laser-actuated micro-drum device of bilayer graphene with controlled number of nanopores, and measuring the permeation rate of different gases, show that it can also be used for permeation-based sensing. [ABSTRACT FROM AUTHOR]

Complex oxide thin films and heterostructures exhibit a variety of electronic phases, often controlled by the mechanical coupling between film and substrate. Recently it has become possible to isolate epitaxially grown single-crystalline layers of these materials, enabling the study of their properties in the absence of interface effects. In this work, we use this technique to create nanomechanical resonators made out of SrTiO3 and SrRuO3. Using laser interferometry, we successfully actuate and measure the motion of the nanodrum resonators. By measuring the temperature-dependent mechanical response of the SrTiO3 resonators, we observe signatures of a structural phase transition, which affects both the strain and mechanical dissipation in the resonators. Here, we demonstrate the feasibility of integrating ultrathin complex oxide membranes for realizing nanoelectromechanical systems on arbitrary substrates and present a novel method of detecting structural phase transitions in these exotic materials. Thin films of complex oxides can be grown and transferred on substrates, which provides opportunities for their manipulation, characterization and potential applications. Here, the authors fabricate and characterize nanodrum resonators of suspended thin single-crystal complex oxides and investigate the temperature dependent properties and associated phase transitions of the isolated ultrathin form. [ABSTRACT FROM AUTHOR]

The article focuses on a research in which researchers used a molecular spin transistor to read the nuclear spin state and measure the relaxation times on spin-flip excitations of an atom. The molecular spin transistor is a three-terminal device in which an individual molecule bridges the gap between two closely spaced metal electrodes. The experiment consists of measuring the differential conductance as a function of the magnetic field.