We have fabricated superconductor-normal metal side-junctions with different barrier transparencies out of PdTe2 crystalline flakes and measured the differential conductance spectra. Modeling our measurements using a modified Blonder Tinkham Klapwijk (BTK) formalism confirms that the superconductivity is mostly comprised of the conventional s-wave symmetry. We have found that for junctions with very low barrier transparencies, the junctions can enter a thermal regime, where the critical current becomes important. Adding this to the BTK-model allows us to accurately fit the experimental data, from which we conclude that the superconductivity in the a-b plane of PdTe2 is dominated by conventional s-wave pairing.

ZrSiS has been identified as a topological material made from non-toxic and earth-abundant elements. Together with its extremely large and uniquely angle-dependent magnetoresistance this makes it an interesting material for applications. We study the origin of the so-called butterfly magnetoresistance by performing magnetotransport measurements on four different devices made from exfoliated crystalline flakes. We identify near-perfect electron-hole compensation, tuned by the Zeeman effect, as the source of the butterfly magnetoresistance. Furthermore, the observed Shubnikov-de Haas oscillations are carefully analyzed using the Lifshitz-Kosevich equation to determine their Berry phase and thus their topological properties. Although the link between the butterfly magnetoresistance and the Berry phase remains uncertain, the topological nature of ZrSiS is confirmed. arXiv:1910.09852v1 [cond-mat.mes-hall]

The field of topological materials science has recently been focussing on three-dimensional Dirac semimetals, which exhibit robust Dirac phases in the bulk. However, the absence of characteristic surface states in accidental Dirac semimetals (DSM) makes it difficult to experimentally verify claims about the topological nature using commonly used surface-sensitive techniques. The chiral magnetic effect (CME), which originates from the Weyl nodes, causes an E · B-dependent chiral charge polarization, which manifests itself as negative magnetoresistance. We exploit the extended lifetime of the chirally polarized charge and study the CME through both local and non-local measurements in Hall bar structures fabricated from single crystalline flakes of the DSM Bi0.97Sb0.03. From the non-local measurement results we find a chiral charge relaxation time which is over one order of magnitude larger than the Drude transport lifetime, underlining the topological nature of Bi0.97Sb0.03.

The helical spin‐momentum locking of an electron in a topological surface state is a feature excellently suited for the use in spintronic applications. Devices are fabricated that allow to generate, transport, and detect the spin‐polarization coming from an electronic current in the topological surface state of BiSbTeSe2; a topological insulator reported to have a negligible bulk contribution to its conduction. The successful creation of such a device is described, as is a study of the generated spin‐polarized current as the BiSbTeSe2 surface state is gated through its Dirac point. A non‐local voltage difference across separated ferromagnetic leads is observed, larger than previously reported in literature. The spin‐polarization has a maximum when the Fermi level crosses the Dirac point.

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