Towards Scanning Tunneling Microscopy Measurements on Cuprates in the Presence of a Transport Current

Copper oxide superconductors (cuprates) are perhaps among the best known strongly correlated materials. Upon chemical (hole) doping of the antiferromagnetic parent compound, a variety of different electronic phases emerges, including a mysterious pseudogap phase and unconventional superconductivity. Alternatively, forcing a transport current can also induce phase transitions [1–4]. In this thesis, we outline the first steps towards the local characterization of these current-induced electronic properties using low-temperature Scanning Tunneling Microscopy (STM). After studying the viability of these experiments, we define different regions in the doping-current phase diagram suitable for the local characterization of the various phases. The large current densities and accurate doping control needed to reach these regions require the usage of thin samples that were proven hard to manufacture. However, we present the first steps towards a simple fabrication method that allows cleaving...Show moreCopper oxide superconductors (cuprates) are perhaps among the best known strongly correlated materials. Upon chemical (hole) doping of the antiferromagnetic parent compound, a variety of different electronic phases emerges, including a mysterious pseudogap phase and unconventional superconductivity. Alternatively, forcing a transport current can also induce phase transitions [1–4]. In this thesis, we outline the first steps towards the local characterization of these current-induced electronic properties using low-temperature Scanning Tunneling Microscopy (STM). After studying the viability of these experiments, we define different regions in the doping-current phase diagram suitable for the local characterization of the various phases. The large current densities and accurate doping control needed to reach these regions require the usage of thin samples that were proven hard to manufacture. However, we present the first steps towards a simple fabrication method that allows cleaving thin exfoliated flakes after being stamped on a Si/SiO2 chip with pre-patterned contacts. After studying and optimizing the cleaving processes of Bi2Sr2CaCu2O8+x flakes onto Gold and Si/SiO2 we conclude that the presented method is not ideal, and suggest more elaborate methods that include conventional lithography approaches.Show less

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Towards Scanning Tunneling Microscopy Measurements on Cuprates in the Presence of a Transport Current