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arXiv · 2411.13176

Spin-phase transition in an array of quantum rings controlled by cavity photons

Vidar Gudmundsson·Vram Mughnetsyan·Hsi-Sheng Goan·Jeng-Da Chai·Nzar Rauf Abdullah·Chi-Shung Tang·Valeriu Moldoveanu·Andrei Manolescu
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Abstract

We model a spin-phase transition in a two-dimensional square array, or a lateral superlattice, of quantum rings in an external perpendicular homogeneous magnetic field. The electron system is placed in a circular cylindrical far-infrared photon cavity with a single circularly symmetric photon mode. Our numerical results reveal that the spin ordering of the two-dimensional electron gas in each quantum ring can be influenced or controlled by the electron-photon coupling strength and the energy of the photons. The Coulomb interaction between the electrons is described by a spin-density functional approach, but the para- and the diamagnetic electron-photon interactions are modeled via a configuration interaction formalism in a truncated many-body Fock-space, which is updated in each iteration step of the density functional approach. In the absence of external electromagnetic pulses this spin-phase transition is replicated in the orbital magnetization of the rings. The spin-phase transition can be suppressed by a strong electron-photon interaction. In addition, fluctuations in the spin configuration are found in dynamical calculations, where the system is excited by a time-dependent scheme specially fit for emphasizing the diamagnetic electron-photon interaction.

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Vidar Gudmundsson, Vram Mughnetsyan, Hsi-Sheng Goan, Jeng-Da Chai, Nzar Rauf Abdullah, Chi-Shung Tang, Valeriu Moldoveanu, Andrei Manolescu. 2024-11-20. Spin-phase transition in an array of quantum rings controlled by cavity photons. https://doi.org/10.1103/physrevb.111.115304

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