Here, we report the systematic study on the planar transport properties of the quasi-two-dimensional (quasi-2D) topological nodal-line semimetal candidate In0.93TaSe2. When rotating magnetic field in the plane, the anisotropic longitudinal resistance and planar Hall resistance are clearly observed and can be well described by the theoretical formulation of the planar Hall effect (PHE). Further analysis demonstrates that the anisotropic orbital resistance rather than the topological-nontrivial chiral anomaly plays a dominant role on the PHE in In0.93TaSe2. Our study provides another platform for understanding the mechanism of PHE, which may also be valuable for future planar Hall sensors based on quasi-2D materials.

We present the thickness dependence of magnetotransport study on the mechanically exfoliated topological superconductor candidate SnTaS2. As the thickness decreases, the superconducting transition temperature Tc is gradually suppressed and ultimately out of detection when the thickness is comparable to the superconducting coherence length. The enhanced disorder with the decrease in thickness is expected to play an important role on the suppressed Tc. Furthermore, the distinct weak antilocalization effect is observed in the SnTaS2 nanoflakes, and the temperature-dependent phase coherence length extracted from weak antilocalization agrees with strong electron–phonon scattering in the sample. Our results provide insight into the electronic properties in the low dimensional limit of topological superconductor candidate SnTaS2.

Here, we report systematic studies on thickness-dependent magnetotransport properties of trigonal layered PtBi2. When the thickness decreases, the metallicity is gradually suppressed, and it ultimately displays a semiconductor-like behavior when the thickness is reduced to 22 nm. Interestingly, the magnetoresistance (MR) decreases gradually as well as the thickness decreases, followed by an abrupt increase in the 22 nm nanoflake. The Hall resistance demonstrates the distinct evolution of an electronic state on thickness, revealing that the carrier compensation mechanism may play a role on the large MR in the 22 nm PtBi2 nanoflake. The scanning transmission electron microscopy image clearly uncovers the surface reconstruction of trigonal PtBi2, and qualitative interpretation is proposed for understanding the thickness-dependent transport properties. Our results provide insight into the electronic properties in the low-dimensional limit of topological semimetal trigonal PtBi2.

Exploring the topological surface state of a topological semimetal by the transport technique has always been a big challenge because of the overwhelming contribution of the bulk state. In this work, we perform systematic angular-dependent magnetotransport measurements and electronic band calculations on SnTaS2 crystals, a layered topological nodal-line semimetal. Distinct Shubnikov–de Haas quantum oscillations were observed only in SnTaS2 nanoflakes when the thickness was below about 110 nm, and the oscillation amplitudes increased significantly with decreasing thickness. By analysis of the oscillation spectra, together with the theoretical calculation, a two-dimensional and topological nontrivial nature of the surface band is unambiguously identified, providing direct transport evidence of drumhead surface state for SnTaS2. Our comprehensive understanding of the Fermi surface topology of the centrosymmetric superconductor SnTaS2 is crucial for further research on the interplay of superconductivity and nontrivial topology.

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