Supercurrent mediated by helical edge modes in bilayer graphene

Bilayer graphene encapsulated in tungsten diselenide can host a weak topological phase with pairs of helical edge states. The electrical tunability of this phase makes it an ideal platform to investigate unique topological effects at zero magnetic field, such as topological superconductivity. Here we couple the helical edges of such a...

Stabilizing the Inverted Phase of a WSe₂/BLG/WSe₂ 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...

Symmetry Breakdown in Franckeite: Spontaneous Strain, Rippling, and Interlayer Moire: Spontaneous Strain, Rippling, and Interlayer Moiré

Franckeite is a naturally occurring layered mineral with a structure composed of alternating stacks of SnS2-like and PbS-like layers. Although this superlattice is composed of a sequence of isotropic two-dimensional layers, it exhibits a spontaneous rippling that makes the material structurally anisotropic. We demonstrate that this rippling...

Tunable Photodetectors via In Situ Thermal Conversion of TiS₃ to TiO₂

In two-dimensional materials research, oxidation is usually considered as a common source for the degradation of electronic and optoelectronic devices or even device failure. However, in some cases a controlled oxidation can open the possibility to widely tune the band structure of 2D materials. In particular, we demonstrate the controlled...

Tunneling spectroscopy of localized states of WS2 barriers in vertical van der Waals heterostructures

In transition metal dichalcogenides, defects have been found to play an important role, affecting doping, spin-valley relaxation dynamics, and assisting in proximity effects of spin-orbit coupling. Here we study localized states in WS2 and how they affect tunneling through van der Waals heterostructures of h-BN/graphene/ WS2/metal. The...

Mesoscopic transport in 2D materials and heterostructures

This thesis presents an experimental work on electronic transport in two-dimensional (2D) van der Waals systems. The variety of the physics of the chapters reflects the exploratory character of the Ph.D. study and demonstrates the versatility and the unique properties of some of the members of the vast group of van der Waals materials. In the...

Weak localization in boron nitride encapsulated bilayer MoS2

We present measurements of weak localization on hexagonal boron nitride encapsulated bilayer MoS2. From the analysis we obtain information regarding the phase coherence and the spin diffusion of the electrons. We find that the encapsulation with boron nitride provides higher mobilities in the samples, and the phase coherence shows improvement...

Multi-terminal electronic transport in boron nitride encapsulated TiS₃ nanosheets

We have studied electrical transport as a function of carrier density, temperature and bias in multi-terminal devices consisting of hexagonal boron nitride (h-BN) encapsulated titanium trisulfide (TiS₃) sheets. Through the encapsulation with h-BN, we observe metallic behavior and high electron mobilities. Below ∼60 K an increase in...

Investigating Laser-Induced Phase Engineering in MoS₂ Transistors

Phase engineering of MoS₂ transistors has recently been demonstrated and has led to record low contact resistances. The phase patterning of MoS₂ flakes with laser radiation has also been realized via spectroscopic methods, which invites the potential of controlling the metallic and semiconducting phases of MoS&#x2082...

Large birefringence and linear dichroism in TiS₃ nanosheets

TiS₃ nanosheets have proven to be promising candidates for ultrathin optoelectronic devices due to their direct narrow band-gap and the strong light-matter interaction. In addition, the marked in-plane anisotropy of TiS₃ is appealing for the fabrication of polarization sensitive optoelectronic devices. Herein, we study...

Efros-Shklovskii variable range hopping and nonlinear transport in 1T/1T′-MoS2

We have studied temperature- and electric-field-dependent carrier transport in single flakes of MoS2 treated with n-butyllithium. The temperature dependence of the four-terminal resistance follows the Efros-Shklovskii variable range hopping conduction mechanism. From measurements in the Ohmic and non-Ohmic regime, we estimate the localization...