Work in Progress: Homodyne Detection of Metal membranes (Collab with Norte Lab)

Using membranes covered either gold or silicon nitride (a superconductor at low temperatures) we are able to measure voltage-induced oscillations in the membrane of 100 kHz and beyond. The membrane has the size of 1mm but has thickness of about 300nm. We find two methods of measuring these oscillations: first by direct current increases. With this method we can measure oscillations in the superconductor coated membrane even when applying as little as -110dBm power. The second method works better for the stiffer gold-coated membrane which does not move as much: the application of the oscillating voltage drives an oscillating conductance which can be measured through a lock-in detection scheme. We are currently working on a Methods paper and then plan to use this technique to study the effects of Casimir forces.

Work in Progress: Enhancement of Atomic Spin Lifetime near Diabolic Point (Collab with QNS)

Iron atoms on a copper nitride lattice have been studied for more than a decade now. They exhibit a strong magnetic anisotropy and are excellent for building atomic chains. Part of the anisotropy causes mixing between two spin states. Through application of a transverse magnetic field this mixing is reducing, which allows the lifetime to be enhanced by three orders of magnitude. From a theoretical point of view, this is done by passing through a so-called diabolic point in parameter space, which is essentially a crossing in the energy spectrum as a function of two parameters (transverse and longitudinal field). For this work I went to the Center for Quantum Nanoscience in Seoul, South Korea.

Calibration Measurements of ESR-measurement for installation of new STM (Collab with QNS)

During my time stay at QNS, I got involved in helping to calibrate a newly-built STM that is capable of ESR-STM called "Eve". This involves performing ESR-STM measurements under various conditions and performing COMSOL simulations to compare the transmission of RF-signal from antenna to tip-sample junction between the standard design described in the next section and the Eve-design in which the antenna loops back to a 50-Ohm terminator. It is found that the second design has a slight advantage in that it can couple to both the tip and sample, increasing viability of the transfer function, while also maintaining better mechanical stability.

Installation of antenna for ESR-STM

In order to stay competitive within the scientific community, installation of proper hardware is necessary. To this end, the installation of an antenna for ESR-STM was deemed necessary in the SPECS JT system. We performed several tests on various antenna designs and finally decided to follow the example of Seiffert et al. and go with an open-ended antenna. We characterized the transmission losses along the lines and were able to identify standing waves between various connectors in the Fourrier spectrum of the transfer function.

Remote Detection of Spin Waves

Spinwaves on atomic chains move with a velocity much greater than the STM tip is able to keep up with. Given that the tip is used for both initialization and read-out of such waves, it would be impossible to test whether a spinwave would reach the end the chain. To circumvent this, we build a detector that has a long lifetime (>1s) that can be queried after the spinwave has passed and decayed, some 10 ps later. Such a structure (shown on top) then allows us to measure the distance these waves can travel as a function of various parameters.

Outreach of my work has led to being nominated for Best Poster Prize at the yearly Dutch Physics Society's convention in Veldhoven in 2020, the third place the Dutch Physic's newsletter for best article and I have also published in the Dutch Vacuum Society's magazine.