Alloys of 2D Transition-Metal Dichalcogenides: Short Intro

Alloys of 2D Transition-Metal Dichalcogenides: Short Intro

Harold Alberto Rojas

Estudiante de Doctorado en Ciencias - Física, Universidad de los Andes

Abstract 1: Transition-metal dichalcogenides (TMD) are composites of the type MX2, with M a transition-metal atom (Mo, W, etc) and X a chalcogen atom (S, Se or Te). TMDs are part of the large family of two-dimensional (2D) materials, which grown in atomically thing layered crystal structures. Interatomic forces between these layers are of Van der Walls form. This feature permits to obtain individual layers from the bulk material. 2D-TMDs have attracted a great deal of interest in recent years because of their possible applications in optoelectronics and clean energy generation, among others. In this seminar I will present a short introduction to the topic of 2D-TMD with a focus on the possibilities opened by alloying these compounds by means of substitutions of chalcogen atoms, M(XxY1−x)2, or transition metal atoms, (MxN1−x)X2, into the structure of the original material MX2.

Quantum Dynamics and Phase Transitions in Low Dimensional Systems

Santiago Higuera

Estudiante de pregrado en Física, Universidad de los Andes

Abstract 2: Low dimensional systems are of great interest in current condensed matter physics, exhibiting new phenomena leading to mesoscopic physics and promises of novel device applications. In this seminar I will review two low dimensional systems: a 0D two-level system under a Landau-Zener (LZ) Hamiltonian and a 1D Wannier-Stark (WS) ladder. The LZ model describes the time evolution of a two-level system under a linear time-dependent Hamiltonian and is the simplest case to evidence the Kibble-Zurek mechanism (KZM), a non-equilibrium model that describes the formation of topological defects across a phase transition and predicts a scaling in topological defect density with the quench rate. First, there will be an introduction to the KZM and presentation of results obtained from simulations on real IBM Quantum computers that validate the main KZM prediction. In second place, I will introduce the WS ladder model of electrons in a crystalline solid under an electric field using the tight-binding approximation and simulations of the quantum dynamics of single and many bodies in this system.