Para-ortho transition of artificial H$_2$ molecule in lateral quantum dots doped with magnetic impurities

TL;DR

This paper investigates the magnetic phase diagram of an artificial H$_2$ molecule in lateral quantum dots doped with magnetic impurities, revealing how magnetic interactions depend on external fields and gate voltages.

Contribution

It introduces a detailed analysis of magnetic phase transitions in doped quantum dots using a configuration-interaction approach and maps electron-Mn interactions to effective models.

Findings

Mn-Mn exchange coupling varies with electron-Mn interaction strength.

Magnetic phase transitions correlate with electron spin states.

RKKY and magnetic-polaron interactions describe different coupling regimes.

Abstract

We present the magnetic phase diagram of artificial H$_2$ molecule in lateral quantum dots doped with magnetic impurities as a function of external magnetic field and plunger gate voltage. The onset of Mn-Mn antiferromagnetic-ferromagnetic transition follows the electron spin singlet-triplet transition. We deploy a configuration-interaction method to exactly diagonalize the electron-Mn Hamiltonian and map it to an effective Mn-Mn Heisenberg Hamiltonian. We find that Mn-Mn exchange coupling can be described by RKKY-interaction/magnetic-polaron in weak/strong electron-Mn coupling at low/high magnetic fields.