Elastic Spin Relaxation Processes in Semiconductor Quantum Dots

TL;DR

This paper provides a comprehensive theoretical analysis of elastic spin relaxation mechanisms in semiconductor quantum dots, highlighting conditions where these processes dominate and their implications for spin decoherence.

Contribution

It introduces a detailed theoretical framework for elastic spin-phonon processes, including intervalley transitions and effects of lattice anharmonicity, expanding understanding of spin decoherence in quantum dots.

Findings

Elastic processes can dominate over inelastic spin-flip transitions under certain conditions.

Intervalley transitions significantly contribute to elastic spin decoherence.

Lattice anharmonicity and phonon decay influence spin relaxation rates.

Abstract

Electron spin decoherence caused by elastic spin-phonon processes is investigated comprehensively in a zero-dimensional environment. Specifically, a theoretical treatment is developed for the processes associated with the fluctuations in the phonon potential as well as in the electron procession frequency through the spin-orbit and hyperfine interactions in the semiconductor quantum dots. The analysis identifies the conditions (magnetic field, temperature, etc.) in which the elastic spin-phonon processes can dominate over the inelastic counterparts with the electron spin-flip transitions. Particularly, the calculation results illustrate the potential significance of an elastic decoherence mechanism originating from the intervalley transitions in semiconductor quantum dots with multiple equivalent energy minima (e.g., the X valleys in SiGe). The role of lattice anharmonicity and phonon decay in spin relaxation is also examined along with that of the local effective field fluctuations caused by the stochastic electronic transitions between the orbital states. Numerical estimations are provided for typical GaAs and Si-based quantum dots.