Integer filling factor phases and isospin in vertical diatomic artificial molecules

Abstract

Integer filling factor phases of many-electron vertically coupled diatomic artificial quantum dot molecules are investigated for different values of the interdot coupling. The experimental results are analyzed within local-spin density functional theory for which we have determined a simple lateral confining potential law that can be scaled for the different coupling regimes, and Hartree-Fock theory. Maximum density droplets composed of electrons in both bonding and antibonding or just bonding states are revealed, and interesting isospinflip physics appears for weak interdot coupling when the systematic depopulation of antibonding states leads to changes in isospin.

Vertically coupled double quantum rings at zero magnetic field

“…A rich interplay between molecular phases with different isospins is expected to appear as a function of B, 15,30 which might have an observable influence on the Aharonov-Bohm effect and on the far-infrared spectroscopy of nanoscopic QRMs. …”

Spin transitions induced by a magnetic field in quantum dot molecules

“…For GaAs the g-factor is g GaAs = −0.44 while for InAs and InSb the g-factors are g InAs = −14, and g InSb = −50. 8,9,10,11,32,33 Hence by adding In one can hope to tune the g-factor of quantum dot molecules.…”

“…The application of spin of electrons in quantum dots for generation of electron entanglement and quantum information processing in solid state devices is of current experimental 1,2,3,4,5,6,7,8,9,10,11 and theoretical interest 12,13,14,15,16,17,18 . Controlling the spin of electrons in single quantum dots by tuning the external magnetic field, the confining potential, number of electrons, and Zeeman coupling has been demonstrated 2,3,4,5,6,7 .…”

Three electrons in laterally coupled quantum dots: Tunnel vs electrostatic coupling, ground-state symmetry, and interdot correlations

“…Artificial molecules are formed by vertically [1][2][3][4][5][6][7][8][9][10][11] coupled dots or by dots coupled laterally. [12][13][14][15][16][17][18][19][20][21][22][23][24][25] The electronic properties of two-electron systems in vertically 4-7 as well as laterally [12][13][14][15][16] coupled dots have been extensively studied by exact methods that for two electrons are particularly convenient due to the separation of the spatial and spin degrees of freedom.…”

“…For larger electron numbers the mean field methods 1-3,18-21 are more commonly used. The mean field approaches give reliable estimates for the ground-state energy and are useful in simulations 2,3,18,19,27 of devices but they possess several shortcomings 28 due to an approximate treatment of the electron-electron correlations, which results in artifactal symmetry-breaking effects leading to an oversimplified picture of Wigner crystallization, to the appearance of spin-density waves, etc.…”