This thesis discusses several studies on magnetic two-dimensional (2D) materials, focusing on their nanomechanical properties and the behavior of resonance frequencies in response to temperature changes. These studies employ nanomechanical resonators, specifically suspended membranes (drum resonators) of 2D magnetic materials. The frequency response of these resonators is measured using optical excitation combined with an interferometric setup, allowing identification of resonance frequencies. By altering the temperature of the resonators, the resonance frequency shifts as the strain within the 2D material changes. This strain change is partially magnetostrictive in origin due to changes in the magnetic order within the materials, offering a method to study these magnetic characteristics...@en

In this thesis, we use methods offered by state of the art nanofabrication and single-molecule measurement techniques to capture polycyclic aromatic hydrocarbon (PAH) all-organic, di-radical molecules in solid-state devices, and study their electronic transport properties in different conditions with a focus on their magnetic properties.@en

This dissertation centers around two topics: graphene nanoribbons (GNRs) and superconductors. The aim of this thesis is to work towards combine these two topics, in order to study how superconducting correlations interact with magnetic correlations within graphene nanoribbons, such as the magnetic edge states present in the zigzag edges of graphene nanoribbons. To introduce superconducting correlations into a graphene nanoribbon, it is important that there is a highly electrically transparent interface between a superconductor and the graphene nanoribbon. This is the main scope of this work.

This work presents research towards using molybdenum rhenium (MoRe) alloy as an electrical contact material for 9 atom wide armchair edge GNRs (9-AGNRs). MoRe electrodes with nanometer-size separations (30 nm and 6 nm) are made and compared with palladium electrodes. Experiments with contacting aerosol gold nanoparticles were performed to confirm that the MoRe electrodes are superconducting and capable of making a clean contact. Beside pure superconducting contacts, Palladium is considered as a contact material, which is made superconducting by the proximity effect. To study the proximity effect, electrical measurements at a base temperature of 30 mK were performed on variable thickness Nb-Au-Nb and Nb-Pd-Nb superconductor-normal metal-superconductor (SNS) junctions made by shadow mask evaporation. A constriction in the Pd layer allows for increasing the junction resistance by feedback-controlled electromigration until a tunnel contact is formed. As the final part of this research, a superconducting diode effect was identified and studied in these SNS junctions. @en

Electrostatically-defined nanostructures in bilayer graphene (BLG), known for its tunable bandgap, have promising applications in spintronics and valleytronics, however, its thermo- transport phenomena have not yet been investigated. This thesis aims to fabricate a BLG field-effect transistor (FET) device and characterize the thermotransport phenomena (See- beck coefficient) in electrostatically defined quantum point contacts (QPCs) and quantum dots (QDs). For this purpose, a bilayer graphene flake is encapsulated in hexagonal boron nitride (hBN) with Ti/Au heaters, top gates and 100-nm-separated split gates placed on top of the upper hBN flake. To define a QD, the 100 nm wide finger gates were separated from the top gates by a 30 nm Al2O3 dielectric. However, the electric field induced by the back gate was being screened by a layer of charges somewhere between the back gate and the bilayer graphene. The origin of this layer of charges remains unknown. As a result, the channel could not be fully depleted (unless when B = 5 T) and showed features indicating an unintended charging and discharging effect somewhere in the sample. As a consequence, the formation of a QD or a QPC at B = 0 T was not possible. Despite that, thermal voltages were measured in the two-dimensional BLG, applying currents up to 50 μA to the aforementioned heaters. The estimated Seebeck coefficient (based on resistance characterizations) was in the range of μV/K (corresponding with theoretical predictions) and enabled an estimate of an induced temperature gradient of 0.5 ± 0.2 K.

This dissertation concerns transport measurements in single-molecule junctions using the mechanically controlled break junction (MCBJ) technique. It describes various aspects that play a role in charge transport through single molecules, in order to develop the necessary knowledge to ultimately develop electronic devices based on intrinsic molecular functionality.@en

This thesis is about measurements of the electrical properties of different families of molecules. The research was focused on fundamental questions of charge transport in organic molecules. With this aim, experiments were performed to shed light on the underlying transport mechanisms. For example, an important ingredient of the work concerned the understanding of quantum interference effects in transport. On the other hand, several bio-inspired molecules were tested as electrical components revealing, for example, that with a certain chemical design a single-curcuminoid molecule act as a switch.@en

This thesis revolves around nanomechanical membranes made of suspended two - dimensional materials. Chapters 1-3 give an introduction to the field of 2D-based nanomechanical devices together with an overview of the underlying physics and the measurementtools used in subsequent chapters. The research topics that are discussed can bedivided into four categories: characterisation (Chapters 4 and 5), sensors (Chapter 6),actuators (Chapters 7 and 8) and novel materials (Chapter 9).@en

This thesis is an experimental investigation of the physical properties of different transition metal oxide ultra-thin films. A common feature of these various materials and structures is that they exhibit a solid-state phase transition from a metallic to an insulating state, which is triggered upon changing sample composition, or by varying an external stimulus such as temperature, illumination or gas pressure. The experiments performed cover a broad spectrum of condensed matter, from material growth, structural characterisation and nanodevice fabrication to low-temperature magnetotransport, synchrotron microscopy and gas sensing.@en