Jingjing Niu

Anomalous Hall effect and magnetic orderings in nanothick V5S8

{\mathrm{ZrTe}}_{5}

Effect of impurity doping in gapped bilayer graphene

is a newly discovered topological material. Shortly after a single layer

Vanishing quantum oscillations in Dirac semimetal ZrTe5

{\mathrm{ZrTe}}_{5}

Ultrafast epitaxial growth of metre-sized single-crystal graphene on industrial Cu foil

had been predicted to be a two-dimensional topological insulator, a handful of experiments have been carried out on bulk

Electrical control of intervalley scattering in graphene via the charge state of defects

{\mathrm{ZrTe}}_{5}

V

crystals, which however suggest that its bulk form may be a three-dimensional topological Dirac semimetal. We report a transport study on ultrathin

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{\mathrm{ZrTe}}_{5}

S

flakes down to 10 nm. A significant modulation of the characteristic resistivity maximum in the temperature dependence by thickness has been observed. Remarkably, the metallic behavior, occurring only below about 150 K in bulk, persists to over 320 K for flakes less than 20 nm thick. Furthermore, the resistivity maximum can be greatly tuned by ionic gating. Combined with the Hall resistance, we identify contributions from a semiconducting and a semimetallic band. The enhancement of the metallic state in thin flakes are a consequence of shifting of the energy bands. Our results suggest that the band structure sensitively depends on the film thickness, which may explain the divergent experimental observations on bulk materials.

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The rise of graphene marks the advent of two-dimensional atomic crystals, which have exhibited a cornucopia of intriguing properties, such as the integer and fractional quantum Hall effects, valley Hall effect, charge density waves and superconductivity, to name a few. Yet, magnetism, a property of extreme importance in both science and technology, remains elusive. There is a paramount need for magnetic two-dimensional crystals. With the availability of many magnetic materials consisting of van der Waals coupled two-dimensional layers, it thus boils down to the question of how the magnetic order will evolve with reducing thickness. Here we investigate the effect of thickness on the magnetic ordering in nanothick V