TipTop · Tip-based imaging of Topological materials

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Project objective

Topological insulators have attracted attention over the past two decades due to their spin-momentum locked edge states hosting ballistic, spin-polarized, transport, useful for energy-efficient computing and spintronics. However, probing these states and confirming their origin remains a challenge, as structural and electronic disorder often obscure transport signatures. To overcome these limitations, TipTop (Tip-based imaging of Topological materials) aims to establish scanning NV magnetometry at cryogenic temperatures as a probe for quantum transport in topological materials, thereby linking morphology and electronic behavior. NV magnetometry uses the spin-dependent fluorescence of nitrogen-vacancy centers in diamond to image magnetic fields with high spatial resolution and sensitivity. The first objective is to reach sub-100 nm spatial resolution with sub-microampere current sensitivity via AC quantum sensing protocols, as already demonstrated at room temperature but not yet optimized for cryogenic operation. This will enable me to apply NV magnetometry to two distinct material platforms. Secondly, I will image the charge current distribution in ultrathin films of (Bi1-xSbx)2Te3, which, depending on thickness, hosts either trivial or topological edge states. However, disorder from dry etching and growth can lead to ambiguous transport signatures, highlighting the current need for spatially resolved probes. Finally, I will analyze superconductivity in WTe2 Josephson junctions. By imaging the supercurrent distribution, I will provide a direct method to search for higher-order topological hinge states and compare the result to reconstructed spatial distributions from transport-only methods. Conducted over a two-year period at ETH Zurich, TipTop will combine transport and NV sensing to advance our understanding of the electronic properties of TIs and establish scanning NV magnetometry as a powerful complement to electronic transport experiments.

Original text from CORDIS.

Participants

• EIDGENOESSISCHE TECHNISCHE HOCHSCHULE ZUERICH · ZuerichCoordinatorSwitzerland

Links

• View on CORDIS
• DOI: 10.3030/101267136