Ultra-thin films with different thicknesses of SrRuO3 were grown epitaxially on SrTiO3. The anomalous Hall effect (AHE) with additional peaks was observed in Hall resistivity measurements as a...Show moreUltra-thin films with different thicknesses of SrRuO3 were grown epitaxially on SrTiO3. The anomalous Hall effect (AHE) with additional peaks was observed in Hall resistivity measurements as a function of field and temperature in a 5 unit cell SrRuO3 film without capping layer. The additional peak phase matches literature, whereas the actual resistivity size is found to be lower. The peaks could be explained by either a topological Hall effect (THE) caused by the presence of a skyrmion lattice or two phases of the AHE corresponding to different interfaces. If the additional effect is a THE, this study confirms the presence of a robust skyrmion phase in ultra-thin SrRuO3 on SrTiO3 without capping layer, while gating experiments indicate that the skyrmion size could be tuned by an electric field.Show less
Motivated by the recent discovery of superconductivity in Magic Angle Twisted Bilayer Graphene, we discuss preparatory work for STM measurements on micrometer-sized graphene flakes. We develop and...Show moreMotivated by the recent discovery of superconductivity in Magic Angle Twisted Bilayer Graphene, we discuss preparatory work for STM measurements on micrometer-sized graphene flakes. We develop and fabricate a dummy sample for testing capacitive navigation in any STM setup with an XY-stage. Furthermore, we calculate the effect of a biased STM tip on the charge distribution in a graphene bilayer. We also estimate the chemical potential shift in a gated graphene sample as a result of the probe tip. All results unambiguously suggest that the STM tip will strongly influence the electrical behavior of the graphene system.Show less
The spectroscopic techniques of ARPES and spectroscopic STM play a key role in strongly correlated electron research due to their ability to resolve k-space. However, due to their different...Show moreThe spectroscopic techniques of ARPES and spectroscopic STM play a key role in strongly correlated electron research due to their ability to resolve k-space. However, due to their different approaches in obtaining k-space information, the two techniques do not necessarily agree on the observed bandstructure. Here, in an attempt to clear the fog between the two, we present FT-STM results on the rhodate Sr2RhO4 focusing on the comparison between our data and previous ARPES studies on the same sample. We deduce the low-energy bandstructure through the modulations of the LDOS caused by impurity scattering. The Fermi surface area and self-energy are then calculated. We find a flattened dispersion compared to the ARPES result which is shown to be in line with previous FT-STM studies on other correlated electron materials.Show less
This thesis presents the characterization of a broadband radio frequency power detector, they key element of the detector being the Herotek DZM020BB diode. The detector has been developed to...Show moreThis thesis presents the characterization of a broadband radio frequency power detector, they key element of the detector being the Herotek DZM020BB diode. The detector has been developed to measure shotnoise signal orig- inating from a UHV low temperature STM tunnel junction. The detector provides fast measurement times of 1 sec while providing enough resolu- tion 0.06μVrms to distinguish between different noise voltages. This detec- tor has been compared to the Zurch MFLI lock in amplifier which measures the shotnoise with measuring times in the order of 10 seconds. Systematic effects in the detector have been studied and possible solutions were sug- gested to eliminate these effects.Show less
In this work, the possibility to measure time- and spatially resolved spin fluctuations using Scanning Tunneling Microscopy is investigated. By using an impedance matching circuit as described in ...Show moreIn this work, the possibility to measure time- and spatially resolved spin fluctuations using Scanning Tunneling Microscopy is investigated. By using an impedance matching circuit as described in [1], the bandwidth of conventional STM can be increased opening up possibilities for new kinds of experiments. When combined with the technique of spin-polarized STM, it theoretically becomes possible to track spin states of individual atoms. Here, we present an overview of existing literature on this topic and propose several experiments to test this hypothesis. Finally, with a python simulation, we test the viability of EPR-STM measurements on a single atom and provide directions to expand upon this work.Show less
Currently the shot noise signal from the STM is measured with the Zurich MFLI lock in amplifier, which has measuring times on the order of 10 seconds. In this research we will build a RF diode...Show moreCurrently the shot noise signal from the STM is measured with the Zurich MFLI lock in amplifier, which has measuring times on the order of 10 seconds. In this research we will build a RF diode detector. Starting out with the Herotek DZM020BB RF diode, we add additional components to increase its performance at measuring small signals. Then we compare its accuracy and measuring times with the Zurich MFLI. The detector had 1/f noise, which was eliminated with the ”tic toc” method. We find a final resolution of 0.06 μV for the detector with 1 s measuring time, which means that it performs better than the Zurich MFLI.Show less
Motional control of mechanical resonators is crucial for their applications. In particular, cooling the mechanical mode to overcome the thermal noise has been greatly explored, and has recently...Show moreMotional control of mechanical resonators is crucial for their applications. In particular, cooling the mechanical mode to overcome the thermal noise has been greatly explored, and has recently been pushed into the quantum regime. In this thesis, we study an almost-forgotten cooling technique: resistive cooling with an artificial cold resistor (ACR) which is physically at room temperature. We perform a proof-of-principle demonstration to cool a mechanical mode of a quartz crystal with a “cold” resistor. The “cold” resistor is realised either by a normal resistor cooled by liquid nitrogen or by an ACR made of a special circuitry. We show that the ACR can cool the mode in the same way as a real cold resistor, and the cooling mechanism can be qualitatively understood in the basic thermodynamic picture. We also discuss the feasibility of applying such resistive cooling to an optomechanical system, with a nested trampoline resonator.Show less
