Surface Acoustic Waves Probe of the Spin Phase Transition at $\nu$=2/3 in n-GaAs/AlGaAs structure

Abstract

High frequency (ac) conductivity in the single quantum well AlGaAs/GaAs/AlGaAs with high mobility was investigated by contactless acoustic methods in the fractional quantum Hall effect regime in perpendicular and tilted magnetic fields. We studied the dependence of ac conductivity ${\sigma }^{ac}={\sigma }_1-i{\sigma }_2$ on both the temperature and magnetic field tilt angle. Tilting the magnetic field relative to the sample surface enabled us to change the position of the conductivity oscillation minimum at $\nu$=2/3. We measured the temperature dependence of ac conductivity for each tilt angle and for the 2/3 state we calculated the activation energy $\Delta E$ which was derived by constructing the Arrhenius plot ln ${\sigma }_1$ against 1/$T$. Analyzing behavior of the activation energy in total magnetic field for the filling factor 2/3 we observed a distinct minimum which can be interpreted as the spin unpolarized-polarized phase transition.

4 pages, 4 figures

References in corpus (6)

• Observation of a new phase transition between fully and partially polarized quantum Hall states with charge and spin gaps at $\nu =2/3$
• Direct measurements of the fractional quantum Hall effect gaps
• Direct Measurement of the g-Factor of Composite Fermions
• Flatland Electrons in High Magnetic Fields
• Acoustic Studies of AC Conductivity Mechanisms in $n$-GaAs/AlGaAs in the Integer and Fractional Quantum Hall Effect Regime
• Spin transition in the fractional quantum Hall regime: Effect of extent of the wave function