arXiv subjects

Oscar Bulancea Lindvall

Publications and source records attributed to Oscar Bulancea Lindvall.

3 recordsLinked to original sources

arXiv2025

Native defects and impurities in talcum quasi-2D layers

Layered semiconductors have recently emerged as capable host materials for novel quantum applications ranging from phonics to sensing. Most studies have focused on artificial layered materials, while natural layered materials, such as talc and other silicates, have remained largely unexplored despite their desirable properties, e.g, wide direct bandgap, low concentration of optically active defects, and low abundance of nuclear spins. In this article, we carry out a comprehensive computational study of pristine and defective talc layers and discuss their potential applications. After investigating bulk properties, such as lattice parameters, band structure, and dielectric constant, we study the electronic structure, charge states, spin and optical properties of vacancy defects, metal, metalloid, and non-metallic impurities. Our results establish the basis for identifying color centers, electron paramagnetic resonance centers, potential spin quantum bits, and p and n-type dopants. These findings mature the theory of talc and point toward potential applications in quantum technologies.

cond-mat.mtrl-sci↗

arXiv2021

Quantum sensor in a single layer van der Waals material

Point defect qubits in semiconductors have demonstrated their outstanding high spatial resolution sensing capabilities of broad multidisciplinary interest. Two-dimensional (2D) semiconductors hosting such sensors have recently opened up new horizons for sensing in the subnanometer scales in 2D heterostructures. However, controlled creation of quantum sensor in a single layer 2D materials with high sensitivity has been elusive so far. Here, we report on a novel 2D quantum sensor, the VB2 centre in hexagonal boron nitride (hBN), with superior sensing capabilities. The centre's inherently low symmetry configuration gives rise to unique electronic and spin properties that implement a qubit in a 2D material with unprecedented sensitivity. The qubit is decoupled from its dense spin environment at low magnetic fields that gives rise to the reduction of the spin resonance linewidth and elongation of the coherence time. The VB2 centre is also equipped with a classical memory that can be utilized in storing population information. Using scanning transmission electron microscopy imaging, we confirm the presence of the point defect structure in free standing monolayer hBN created by electron beam irradiation. Our results provide a new material solution towards atomic-scale sensing in low dimensions.

cond-mat.mes-hall↗

arXiv2021

Dipolar spin relaxation of divacancy qubits in silicon carbide

Divacancy spins in silicon carbide implement qubits with outstanding characteristics and capabilities in an industrial semiconductor host. On the other hand, there are still numerous open questions about the physics of divacancy point defects, for instance, spin relaxation has not been thoroughly studied yet. Here, we carry out a theoretical study on environmental spin induced spin relaxation processes of divacancy qubits in 4H-SiC. We reveal all the relevant magnetic field values where the longitudinal spin relaxation time T$_1$ drops resonantly due to the coupling to either nuclear spins or electron spins. We quantitatively analyze the dependence of the T$_1$ time on the concentration of point defect spins and the applied magnetic field in the most relevant cases and provide an analytical expression. We demonstrate that dipolar spin relaxation plays a significant role both in as-grown and ion implanted samples and it often limits the coherence time in 4H-SiC.

cond-mat.mes-hall↗