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Friday, July 28, 2017 — 11:45 AM to 12:45 PM EDT

Dimensionality-driven orthorhombic MoTe2 at room temperature.

Joey Zhong

We use a combination of Raman spectroscopy and transport measurements to study thin flakes of the type-II Weyl semimetal candidate MoTe2 protected from oxidation. In contrast to bulk crystals, which experience a phase transition from monoclinic to the inversion symmetry breaking, orthorhombic phase below ~250 K, we find that in moderately thin samples below 10 nm, a single orthorhombic phase exists up to and beyond room temperature. We attribute this to the effect of c-axis quantum confinement, which lowers the energy of an out-of-plane hole band and stabilizes the orthorhombic structure. At low temperature (<20K), bulk MoTe2 shows huge magneto resistance (MR). This is due to balanced electron and hole carrier. For thin MoTe2, we found the MR is reduced as compared to the bulk. This suggests the balance between electron and holes carrier no longer holds. We also looked at the Shubnikov-de Haas (SdH) oscillations and our preliminary findings are consistent with this hypothesis.

Location 
RAC - Research Advancement Centre
2009
475 Wes Graham Way

Waterloo, ON N2L 6R2
Canada

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