Multiple external tuning parameters affecting the different Charge Density Wave (CDW) phase transitions in few-layer 1T-TaS2 have been reported in literature. The formation of CDWs still lacks a...Show moreMultiple external tuning parameters affecting the different Charge Density Wave (CDW) phase transitions in few-layer 1T-TaS2 have been reported in literature. The formation of CDWs still lacks a predictive theory, so understanding may be gained from experiments on the effects favoring or suppressing CDW transitions. In this project we performed electronic transport measurements on ~ 100nm thin 1T-TaS2 at 1.55K to 290K. Flakes of 1T-TaS2 were exfoliated and stamped on top of Au contacts to form a Hall bar. The Charge Density Wave transition is observed between T = 100K and 160K with a relaxation time in the range of hours. Consequently, the transition can be suppressed by fast cooling and we find a range of metastable states, that are supposedly coexisting spatially separated domains of NC- and C-CDW. Under application of a magnetic field, the change of sign of the Hall voltage at the transition is confirmed. Both CDW phases show positive magnetoresistance along the channel with similar shape, whilst the effect is more pronounced in the C-CDW phase. The magnetoresistance effect is attributed to Weak Anti Localization, which would also explain a decrease in resistivity seen in the supercooled NC-CDW phase at low temperature. The slow transition and the magnitude of resistivity increase, that is about two times lower than reported in literature, may be caused by defects in the crystal hindering long-range CDW order.Show less
Electromigration in bismuth is studied as a way to create bismuth(111) bilayers. Temperature-dependent electromigration measurements have been performed and a model incorporating Joule heating is...Show moreElectromigration in bismuth is studied as a way to create bismuth(111) bilayers. Temperature-dependent electromigration measurements have been performed and a model incorporating Joule heating is used to describe those. An activation energy for diffusion between 100 and 180meV is found. Furthermore, in-situ electromigration experiments have been performed in a scanning electron microscope. This allowed us to link events in the conductance traces of bismuth constrictions during electromigration to visual features. Specifically, remerging of the bismuth electrodes was found to cause increases in conduction.Show less
