THEORETICAL STUDY OF SPIN DEFECTS WITH AN HUBBARD MODEL COMBINED WITH DENSITY FUNCTIONAL THEORY CALCULATIONS

ORAL

Abstract

Crystal point defects offer one possible pathway towards the solid-state implementation of quantum applications like nanoscale sensors for magnetometry or thermometry, single photon emission, or qubits for quantum computing. Conditions for such applications are that the defect has a high spin state in the ground state, a long spin lifetime (coherence) time which characterizes the timescale on which the spin retains its polarization (phase), and offers the possibility to manipulate the spin state by optical excitations and to control it with magnetic, electric or strain fields.

In the present work, we combine first-principle generalized DFT calculations with an in-house extended Hubbard model to describe the defect many-body energy states of some points defects. Using DFT and the ΔSCF method, we performed calculations of the ground state and of some excited states total energies, which we used to parameterize our Hubbard model. We apply our methods to the case of the negatively charged nitrogen-vacancy center, computed with DFT-HSE06, as well as to the to the carbon-vacancy-carbon complex in alpha boron, computed with DFT-GGA.

*Calculations have been performed with the QUANTUM ESPRESSO software and access to HPC resources granted by the IDRIS, CINES, TGCC national centers (GENCI Project 2210), by IPP and DIM SIRTEQ (3Lab cluster), and by the Partnership for Advanced Computing in Europe (Project 2019204962). We acknowledge supports from the BCSi, SADAPTH & 21-CMAQ-002 ANR projects.

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Publication: Thermodynamical stability of carbon-based defects in α boron from first principles
Y. Cho, J. Sjakste, O. Hardouin Duparc, N. Vast
Solid State Sciences 154, 107610 (2024) https://doi.org/10.1016/j.solidstatesciences.2024.107610

The effect of pressure on the intrinsic optical dynamics of NV- colored centers in diamond, Alan Custodio dos Reis Souza, Mariya Romanova, Michele Casula, Jelena Sjakste, and Nathalie Vast (in preparation).

New theoretical method to design quasi-atomic systems in the band gap of semiconductors by combining density functional theory (DFT) and the Hubbard effective Hamiltonian (in preparation)
Y. Cho, Alan Custodio dos Reis Souza, Mariya Romanova, J. Sjakste, Michele Casula, N. Vast

Presenters

  • Nathalie Vast

    • CEA-Saclay

Authors

  • Nathalie Vast

    • CEA-Saclay

  • Yeonsoo Cho

    • Ecole Polytechnique

  • Alan CUSTODIO DOS REIS SOUZA

    • LSi

  • Jelena Sjakste

    • CNRS - Laboratoire des Solides Irradies (LSI)

  • Michele Casula

    • CNRS

  • Mariya ROMANOVA

    • CEA Cadarache