Phase transitions in a multiple quantum well in strong magnetic fields

Magnetic field induced charge redistribution in artificially disordered quantum Hall superlattices

“…Apparently, as postulated in refs. [6][7][8][9][10][11], the observed magnetic field driven redistribution of the electron density relies on the negative exchange and correlation energies being larger that the positive kinetic and Hartree energies, which is favorable in the quantum limit. Moreover, the magnetic field driven interwell charge transfer caused by exchange-correlation energy has been observed in double and triple quantum wells in refs.…”

“…Additional controlled degrees of freedom in the growth direction may be introduced into the problem by (a) E-mail: pusep@ifsc.usp.br fabrication of the multiple-well quantum Hall systems, where the density of 3DEG is modulated by a periodic potential which breaks the translational crystal symmetry resulting in new gaps [5]. Diverse broken-symmetry phases such as spontaneous interlayer phase coherent and charge-ordered states were demonstrated to occur in such multiple-well systems in the presence of a strong magnetic field as a result of both the electron density modulation and many-body effects [6][7][8][9][10][11]. Their predominance is established by the well separation.…”

“…The observed transition manifested itself in a corresponding change of the slope of the Hall resistance and it was understood as a kind of quantum phase transition leading to a spatial redistribution of the charge in a multi-component electron system predicted in refs. [7][8][9]11]. A mostly straightforward observation of charge distribution can be obtained by measurements of the local electron density.…”

Magnetotransport in a wide parabolic well superimposed with a superlattice

“…[8][9][10][11][12] We found that the interlayer disorder favors the observed transition. According to theory, 10 however, interlayer tunneling stabilizes the interlayer phase coherence.…”

Scenario for fractional quantum Hall effect in bulk isotropic materials

“…12 In multilayer systems at small d͑d / l Ͻ 0.9 ͱ 2 ͒, interlayer repulsions favor an inplane lattice that is square as this permits larger separations between sites in neighboring planes. 9 As d decreases, multiple phase transitions between different stackings of squares in the vertical direction occur; Ref. 9 identifies states in which electrons at the same in-plane coordinates are sepa-rated by M = 2, 4, or 5 layers, as well as states with incommensurate stackings.…”