Ising quantum Hall ferromagnetism in InSb-based two-dimensional electronic systems

Abstract

We report on the observation of Ising quantum Hall (QH) ferromagnetism in two-dimensional electronic systems based in single InSb/InAlSb quantum wells. Magneto-transport experiments in tilted magnetic fields reveal the preservation of the = 2 and = 3 QH states over the range in tilt angles where the single particle gap is expected to collapse for a noninteracting system. These preserved QH states are accompanied by broad resistance peaks which move towards higher filling factors as the tilt angle is increased and which display hysteresis. The maximum in the amplitude of these resistance peaks grows with increasing temperature and is activated as exp͑−1 / ͱ T͒.

Giant enhanced g-factors in an InSb two-dimensional gas

“…Previous investigations of Zeeman splitting in narrowergap semiconductors have usually led to indications of g-factor enhancement [14][15][16][17][18] although some authors suggest that the effect is small. 19 To date however no systematic studies comparable to the work performed in GaAs and silicon have been reported.…”

“…The coincidence causes the merging of the splitresistivity peaks which occurs alternately for even and odd values of at odd and even values of R. The only exception to this is the = 2 crossing where the Ising quantum-Hall ferromagnet state is formed causing a resistance spike at the crossing, 25 as reported previously. 16,26 An accurate measurement of the coincidence is made by plotting the resistivity at integer occupancies which shows a peak as a function of angle, as shown in Fig. 2.…”

Anticrossings of spin-split Landau levels in an InAs two-dimensional electron gas with spin-orbit coupling

“…To describe the repulsion of Landau levels close to the coincidence additional effects need to be considered. SO coupling can play an important role [9,10,11] but it cannot couple any pair of Landau levels [24,25]. Whereas the levels mixing at r = 1 and r = 3 (i.e., the difference between the orbital numbers of the degenerate levels is ∆n = 1 and ∆n = 3 respectively) is allowed and can lead to anti-crossings at even filling factors, the coupling of Landau levels with ∆n = 2, r = 2 is prohibited.…”

Quantum Hall Ferromagnetism In InSb Heterostructures

“…Quantum Hall ferromagnetism (QHF) deep in the integer quantum Hall (QH) regime (ν > 1) has been the subject of recent intense experimental study [1][2][3][4][5]. Quantum Hall ferromagnets develop when the Fermi level lies between two degenerate states where manybody interactions sustain the otherwise vanishing QH gap.…”

“…In the integer QH regime, levels are forced into degeneracy by using gate voltages [5] or a tilted field technique [1][2][3][4]. In the latter, the cyclotron gap (ħeB perp /mc), which depends on the perpendicular component of the applied magnetic field, is kept constant while the Zeeman gap (g*µ B B), which is sensitive to the total field, is increased.…”