He3-Cryostat with superconducting magnet

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We request funding for a He3-cooled cryostat with a superconducting magnet for the integration of a home-built scanning tunneling microscope. In order to meet the scientific goals specified below we aim for a sample temperature < 500 mK. Low mechanical noise is required for reliable operation of the scanning tunneling microscope. The integration in an already existing ultra-high vacuum system requires CF-compatible flanges. The cryostat will be used for reaching the following scientific goals: (i) The investigation of potential topological superconductors and (ii) the characterization of electronic states of pure and (magnetically) doped topological insulators. The new system will enable us to achieve better insight into the above-mentioned material systems. We will design and assemble a low-temperature scanning tunneling microscope with a base sample temperature between 350 mK bis 500 mK, thereby enhancing the energy resolution by about a factor of 2,5–3 in comparison to microscopes already in use in our research group. In the context of (i) the requested setup will be enable us to access sample systems the superconducting properties of which could not be investigated so far because of their very low critical temperature. Furthermore, the much better energy resolution will allow for a better separation between potential Majorana states and other, competing effects, such as Shiba and Caroli-de Gennes-Matricon states. Regarding (ii) the enhanced energy resolution will allow for a better understanding of the Landau level life time in topological insulators where we hope to unravel the relevant scattering properties.