Calibrated force measurement in Atomic Force Microscopy using the Transient Fluctuation Theorem

Quantum calibrated magnetic force microscopy

We report the quantum calibration of a magnetic force microscope (MFM) by measuring the two-dimensional magnetic stray field distribution of the MFM tip using a single nitrogen vacancy (NV) center in diamond. From the measured stray field distribution and the mechanical properties of the cantilever a calibration function is derived allowing to convert MFM images to quantum calibrated stray field maps. This novel approach overcomes limitations of prior MFM calibration schemes and allows quantum calibrated nanoscale stray field measurements in a field range inaccessible to scanning NV magnetomet…

A Ti/Pt/Co multilayer stack for transfer function based magnetic force microscopy calibrations

Magnetic force microscopy is a widespread technique for imaging magnetic structures with a resolution of some 10 nanometers. MFM can be calibrated to obtain quantitative spatially resolved magnetization data in units of A/m by determining the calibrated point spread function of the instrument, its instrument calibration function (ICF), from a measurement of a well-known reference sample. Beyond quantifying the MFM data, a deconvolution of the MFM image data with the ICF also corrects the smearing caused by the finite width of the MFM tip stray field distribution. However, the quality of the ca…

Steady-state and transient behavior in dynamic atomic force microscopy

We discuss the influence of external forces on the motion of the tip in dynamic atomic force microscopy (AFM). First, a compact solution for the steady-state problem is derived employing a Fourier approach. Founding on this solution, we present an analytical framework to describe the transient behavior of the tip after perturbations of tip-sample forces and the excitation signal. The static and transient solutions are then combined to obtain the baseband response of the tip, i.e., the deflection signal demodulated with respect to the excitation. The baseband response generalizes the amplitude …

WS2-WSe2面内异质结中超快载流子分离的瞬态反射显微成像

Ultrafast carriers' separation imaging in WS2-WSe2 in plane heterojunction by transient reflectivity microscopy

本研究利用瞬态反射显微术直接成像WS2-WSe2面内异质结的电荷分离，测得电子和空穴漂移速度分别为30 nm/ps和10.6 nm/ps，耗尽层宽度300 nm，为纳米器件电光分析提供新途径。

Transient absorption and photocurrent microscopy show hot electron supercollisions describe the rate-limiting relaxation step in graphene

Using transient absorption (TA) microscopy as a hot electron thermometer we show disorder-assisted acoustic-phonon supercollisions (SCs) best describes the rate-limiting relaxation step in graphene over a wide range of lattice temperatures ($T_l=$5-300 K), Fermi energies ($E_F=\pm0.35$ eV), and optical probe energies (~0.3 - 1.1 eV). Comparison with simultaneously collected transient photocurrent, an independent hot electron thermometer, confirms the rate-limiting optical and electrical response in graphene are best described by the SC-heat dissipation rate model, $H=A(T^3_e- T^3_l)$. Our data…

Light-dependent Impedance Spectra and Transient Photoconductivity in a Ruddlesden-Popper 2D Lead-halide Perovskite Revealed by Electrical Scanned Probe Microscopy and Accompanying Theory

Electric force microscopy was used to record the light-dependent impedance spectrum and the probe transient photoconductivity of a film of butylammonium lead iodide, BA$_{2}$PbI$_{4}$, a 2D Ruddlesden--Popper perovskite semiconductor. The impedance spectrum of BA$_{2}$PbI$_{4}$ showed modest changes as the illumination intensity was varied up to 1400 mW/cm$^{2}$, in contrast with the comparatively dramatic changes seen for 3D lead-halide perovskites under similar conditions. BA$_{2}$PbI$_{4}$'s light-induced conductivity had a rise time and decay time of $\sim$ 100 $μ$s, 10$^{4}$ slower than e…