arXiv subjects

M. J. Rost

Publications and source records attributed to M. J. Rost.

3 recordsLinked to original sources

arXiv2026

True Alternating Current Scanning Tunneling Microscope (ACSTM): tunneling on insulators

Scanning Tunneling Microscopy (STM) has revolutionized our atomic scale understanding of surfaces and accelerated progress in nanotechnology. This technique, however, is restricted to metal or semiconducting samples, as it requires a tiny current to stabilize the tip-sample distance with atomic scale precision. We developed a new imaging and feedback method that relies on true alternating current (AC) without any direct current (DC) component. This technique does not only enable the imaging on non-conducting surfaces with atomic resolution, like (thin) glass and oxides, it provides also access to high-frequency electronic sample information. We demonstrate that it is possible to measure on 25nm thick silicon oxide with 10 MHz tunneling current.

physics.ins-det↗

arXiv2023

Open-access microcavities: high stability without dedicated mechanical low-pass filter in closed-cycle cryostats

Open-access optical microcavities are Fabry-Perot type cavities consisting of two micrometer-size mirrors, separated by an air (or vacuum) gap typically of a few micrometers. Compared to integrated microcavities, this configuration is more flexible as the relative position of the two mirrors can be tuned, allowing to change on demand parameters such as cavity length and mode volume, and to select specific transverse cavity modes. These advantages come at the expense of mechanical stability of the cavity itself, which is particularly relevant in noisy closed-cycle cryostats. Here we show an open-access optical microcavity based on scanning-probe microscope design principles. When operated at 4 K in a tabletop optical closed-cycle cryostat without any dedicated low-pass filter, we obtain stabilities of 5.7 and 10.6 pm rms in the quiet and full period of the cryocooler cycle, respectively. Our device has free-space optical access, essential for instance for full polarization control.

physics.ins-det↗

arXiv2016

Friction as Contrast Mechanism in Heterodyne Force Microscopy

The nondestructive imaging of subsurface structures on the nanometer scale has been a long-standing desire in both science and industry. A few impressive images were published so far that demonstrate the general feasibility by combining ultrasound with an Atomic Force Microscope. From different excitation schemes, Heterodyne Force Microscopy seems to be the most promising candidate delivering the highest contrast and resolution. However, the physical contrast mechanism is unknown, thereby preventing any quantitative analysis of samples. Here we show that friction at material boundaries within the sample is responsible for the contrast formation. This result is obtained by performing a full quantitative analysis, in which we compare our experimentally observed contrasts with simulations and calculations. Surprisingly, we can rule out all other generally believed responsible mechanisms, like Rayleigh scattering, sample (visco)elasticity, damping of the ultrasonic tip motion, and ultrasound attenuation. Our analytical description paves the way for quantitative SubSurface-AFM imaging.

cond-mat.mtrl-sci↗