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Edge-Driven Phase Transitions in 2D Ice
Suchit Negi, Alexandra Carvalho, Maxim Trushin +1
2D water, confined by atomically flat layered materials, may transit into various crystalline phases even at room temperature. However, to gain full control over the crystalline st…
Two-dimensional Square Buckled Rashba Lead Chalcogenides
Paul Z. Hanakata, A. S. Rodin, Alexandra Carvalho +3
We propose the lead sulphide (PbS) monolayer as a 2D semiconductor with a large Rashba-like spin-orbit effect controlled by the out-of-plane buckling. The buckled PbS conduction ba…
2D materials and van der Waals heterostructures
K. S. Novoselov, A. Mishchenko, A. Carvalho +1
The physics of two-dimensional (2D) materials and heterostructures based on such crystals has been developing extremely fast. With new 2D materials, truly 2D physics has started to…
Polarization and valley switching in monolayer group-IV monochalcogenides
Paul Z. Hanakata, Alexandra Carvalho, David K. Campbell +1
Group-IV monochalcogenides are a family of two-dimensional puckered materials with an orthorhombic structure that is comprised of polar layers. In this article, we use first princi…
Multiferroic Two-Dimensional Materials
L. Seixas, A. S. Rodin, A. Carvalho +1
The relation between unusual Mexican-hat band dispersion, ferromagnetism and ferroelasticity is investigated using a combination of analytical, first-principles and phenomenologica…
Atomically thin dilute magnetism in Co-doped phosphorene
L. Seixas, A. Carvalho, A. H. Castro Neto
Two-dimensional dilute magnetic semiconductors can provide fundamental insights in the very nature of magnetic orders and their manipulation through electron and hole doping. Despi…
Tunable optical properties of multilayers black phosphorus thin films
Tony Low, A. S. Rodin, A. Carvalho +4
Black phosphorus thin films might offer attractive alternatives to narrow gap compound semiconductors for optoelectronics across mid- to near-infrared frequencies. In this work, we…
Photocarrier relaxation in two-dimensional semiconductors
Daichi Kozawa, Rajeev Kumar, Alexandra Carvalho +8
Two-dimensional (2D) crystals of semiconducting transition metal dichalcogenides (TMD) absorb a large fraction of incident photons in the visible frequencies despite being atomical…
Origin of indirect optical transitions in few-layer MoS2, WS2 and WSe2
Weijie Zhao, R. M. Ribeiro, Minglin Toh +4
It has been well established that single layer MX2 (M=Mo,W and X=S,Se) are direct gap semiconductors with band edges coinciding at the K point in contrast to their indirect gap mul…
Electronic structure modification of Si-nanocrystals with F4 -TCNQ
A. Carvalho, J. Coutinho, M. Barroso +4
We use first-principles models to demonstrate how an organic oxidizing agent, F4 -TCNQ (7,7,8,8- tetracyano-2,3,5,6-tetrafluoroquinodimethane), modifies the electronic structure of…
Band nesting and the optical response of two-dimensional semiconducting transition metal dichalcogenides
A. Carvalho, R. M. Ribeiro, A. H. Castro Neto
We have studied the optical conductivity of two-dimensional (2D) semiconducting transition metal dichalcogenides (STMDC) using ab-initio density functional theory (DFT). We find th…
Doping of Si nanoparticles: the effect of oxidation
A. Carvalho, S. Oberg, M. Barroso +2
The preferred location of boron and phosphorus in oxidized free-standing Si nanoparticles was investigated using a first-principles density functional approach. The calculated form…