arXiv subjects

F. Hastreiter

Publications and source records attributed to F. Hastreiter.

4 recordsLinked to original sources

arXiv2000

Opening an energy gap in an electron double layer system at integer filling factor in a tilted magnetic field

We employ magnetocapacitance measurements to study the spectrum of a double layer system with gate-voltage-tuned electron density distributions in tilted magnetic fields. For the dissipative state in normal magnetic fields at filling factor $ν=3$ and 4, a parallel magnetic field component is found to give rise to opening a gap at the Fermi level. We account for the effect in terms of parallel-field-caused orthogonality breaking of the Landau wave functions with different quantum numbers for two subbands.

cond-mat.mes-hall↗

arXiv1999

Canted antiferromagnetic phase in a double quantum well in a tilted quantizing magnetic field

We investigate the double-layer electron system in a parabolic quantum well at filling factor $ν=2$ in a tilted magnetic field using capacitance spectroscopy. The competition between two ground states is found at the Zeeman splitting appreciably smaller than the symmetric-antisymmetric splitting. Although at the transition point the system breaks up into domains of the two competing states, the activation energy turns out to be finite, signaling the occurrence of a new insulator-insulator quantum phase transition. We interpret the obtained results in terms of a predicted canted antiferromagnetic phase.

cond-mat.mes-hall↗

arXiv1998

Hybridization of electron subbands in a double quantum well at quantizing magnetic field

We employ magnetocapacitance and far-infrared spectroscopy techniques to study the spectrum of the double-layer electron system in a parabolic quantum well with a narrow tunnel barrier in the centre. For gate-bias-controlled asymmetric electron density distributions in this soft two-subband system we observe both individual subband gaps and double layer gaps at integer filling factor $ν$. The bilayer gaps are shown to be either trivial common for two subbands or caused by hybridization of electron subbands in magnetic field. We describe the observed hybrid gaps at $ν=1$ and $ν=2$ within a simple model for the modified bilayer spectrum.

cond-mat.mes-hall↗

arXiv1998

Magnetic-Field-Induced Hybridization of Electron Subbands in a Coupled Double Quantum Well

We employ a magnetocapacitance technique to study the spectrum of the soft two-subband (or double-layer) electron system in a parabolic quantum well with a narrow tunnel barrier in the centre. In this system unbalanced by gate depletion, at temperatures $T\agt 30$ mK we observe two sets of quantum oscillations: one originates from the upper electron subband in the closer-to-the-gate part of the well and the other indicates the existence of common gaps in the spectrum at integer fillings. For the lowest filling factors $ν=1$ and $ν=2$, both the common gap presence down to the point of one- to two-subband transition and their non-trivial magnetic field dependences point to magnetic-field-induced hybridization of electron subbands.

cond-mat.mes-hall↗