7 research outputs found
Boosting proximity spin orbit coupling in graphene/WSe heterostructures via hydrostatic pressure
Van der Waals heterostructures composed of multiple few layer crystals allow
the engineering of novel materials with predefined properties. As an example,
coupling graphene weakly to materials with large spin orbit coupling (SOC)
allows to engineer a sizeable SOC in graphene via proximity effects. The
strength of the proximity effect depends on the overlap of the atomic orbitals,
therefore, changing the interlayer distance via hydrostatic pressure can be
utilized to enhance the interlayer coupling between the layers. In this work,
we report measurements on a graphene/WSe heterostructure exposed to
increasing hydrostatic pressure. A clear transition from weak localization to
weak anti-localization is visible as the pressure increases, demonstrating the
increase of induced SOC in graphene
Revealing the band structure of ZrTe using Multicarrier Transport
The layered material ZrTe appears to exhibit several exotic behaviors
which resulted in significant interest recently, although the exact properties
are still highly debated. Among these we find a Dirac/Weyl semimetallic
behavior, nontrivial spin textures revealed by low temperature transport, and a
potential weak or strong topological phase. The anomalous behavior of
resistivity has been recently elucidated as originating from band shifting in
the electronic structure. Our work examines magnetotransport behavior in
ZrTe samples in the context of multicarrier transport. The results, in
conjunction with ab-initio band structure calculations, indicate that many of
the transport features of ZrTe across the majority of the temperature range
can be adequately explained by the semiclassical multicarrier transport model
originating from a complex Fermi surface.Comment: Main Text: 10 pages, 5 figures; Supporting Information: 10 pages, 7
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Tailoring the Band Structure of Twisted Double Bilayer Graphene with Pressure.
Twisted two-dimensional structures open new possibilities in band structure engineering. At magic twist angles, flat bands emerge, which gave a new drive to the field of strongly correlated physics. In twisted double bilayer graphene dual gating allows changing of the Fermi level and hence the electron density and also allows tuning of the interlayer potential, giving further control over band gaps. Here, we demonstrate that by application of hydrostatic pressure, an additional control of the band structure becomes possible due to the change of tunnel couplings between the layers. We find that the flat bands and the gaps separating them can be drastically changed by pressures up to 2 GPa, in good agreement with our theoretical simulations. Furthermore, our measurements suggest that in finite magnetic field due to pressure a topologically nontrivial band gap opens at the charge neutrality point at zero displacement field
Stabilizing the Inverted Phase of a WSe 2 /BLG/WSe 2 Heterostructure via Hydrostatic Pressure
Bilayer graphene (BLG) was recently shown to host a band-inverted phase with unconventional topology emerging from the Ising-type spin–orbit interaction (SOI) induced by the proximity of transition metal dichalcogenides with large intrinsic SOI. Here, we report the stabilization of this band-inverted phase in BLG symmetrically encapsulated in tungsten diselenide (WSe2) via hydrostatic pressure. Our observations from low temperature transport measurements are consistent with a single particle model with induced Ising SOI of opposite sign on the two graphene layers. To confirm the strengthening of the inverted phase, we present thermal activation measurements and show that the SOI-induced band gap increases by more than 100% due to the applied pressure. Finally, the investigation of Landau level spectra reveals the dependence of the level-crossings on the applied magnetic field, which further confirms the enhancement of SOI with pressure
New method of transport measurements on van der Waals heterostructures under pressure
The interlayer coupling, which has a strong influence on the properties of van der Waals heterostructures, strongly depends on the interlayer distance. Although considerable theoretical interest has been demonstrated, experiments exploiting a variable interlayer coupling on nanocircuits are scarce due to the experimental difficulties. Here, we demonstrate a novel method to tune the interlayer coupling using hydrostatic pressure by incorporating van der Waals heterostructure based nanocircuits in piston-cylinder hydrostatic pressure cells with a dedicated sample holder design. This technique opens the way to conduct transport measurements on nanodevices under pressure using up to 12 contacts without constraints on the sample at the fabrication level. Using transport measurements, we demonstrate that a hexagonal boron nitride capping layer provides a good protection of van der Waals heterostructures from the influence of the pressure medium, and we show experimental evidence of the influence of pressure on the interlayer coupling using weak localization measurements on a transitional metal dichalcogenide/graphene heterostructure