SCES on the Nanoscale

(Left) 4K STM head (Middle panels) Real space dI/dV map taken with our instrument and Fourier transform of the data unveiling momentum space information of the excitation spectrum. (Right panel) The STM is fully UHV compatible allowing the study of thin film materials (see below).

Our first instrument is a 4K UHV compatible SI-STM capable of studying both bulk and thin film samples (see below). The key current purpose is the study of 3D Dirac electron and topological insulator materials.

(Left Panel) Newly installed vector magnet with 1 K insert. (Right Panel) Rendered version of our newly built UHV chamber for thin film and bulk sample handling.

We recently installed a new UHV compatible 9T/3T+3T vector magnet system currently operating at 1 K and to be upgraded to sub-K temperatures. The lab space decoration is the result of an outreach program with the local kindergarten.

Topograph of MBE grown sample (Pb on STO) taken with one of our UHV compatible low temperature STMs after transfer with UHV suitcase.

In collaboration with Hiro Nakamura at the MPI for Solid State Research we are developing and setting up infrastructure for STM studies of MBE and PLD grown samples. For this we have installed a Unisoku STM / q-plus AFM system directly mounted on the MBE chamber for sample characterisation and have developed infrastructure to transfer thin film samples under UHV conditions to our low temperature SI-STMs (see figure below).

Standard thermodynamic setups for specific heat and magnetotorque used by us for thin film and nanogram crystal research of strongly correlated materials as well as prototyping for new techniques tailored to thin films.

Thin film designer heterostructures grown by molecular beam epitaxy (MBE) or pulsed laser deposition (PLD) are a key research field both for the fundamental questions that new classes of materials are posing as well as the potential for being a key part of future technologies due to the possible integration of the properties of different functional materials.

However, while such systems can be readily studied by charge transport and modern spectroscopies, measurements of fundamental thermodynamic properties pose a substantial experimental challenge. The key problem is the small intrinsic 'thermal mass' of such systems which are often less than 100 nm thick. In our group we are pushing existing technologies to their limits to access a very small number of such materials. In parallel we very recently started to explore new technologies to build bespoke thermodynamic apparatus tailored to the demands of thin films. As a 'side product' such techniques will also be suitable for the study of nanogram bulk crystals.