Electronic Transport Properties of the Ising Quantum Hall Ferromagnet in a Si Quantum Well

Magnetotransport properties are investigated for a high mobility Si two-dimensional electron system in the vicinity of a Landau level crossing point. At low temperatures, the resistance peak having a strong anisotropy shows large hysteresis which is attributed to Ising quantum Hall ferromagnetism. The peak is split into two peaks in the paramagnetic regime. A mean field calculation for the peak positions indicates that electron scattering is strong when the pseudospin is partially polarized. We also study the current-voltage characteristics which exhibit a wide voltage plateau.

Figure 1

(a) Schematic view of the central part of the sample located in a tilted magnetic field. (b) Landau level configuration in a tilted magnetic field. (c) The longitudinal resistivity as a function of $\theta$ for $\phi =0°$ and 90° at $T=300\mathrm{mK}$. The magnetic field of 6.4 T is chosen so that $\nu$ equals to 4.0 at the resistance peak.

Figure 2

Hysteresis of the $\theta$-dependence of ${\rho }_{xx}$ plotted as a function of $B_{\perp }$ for $\phi =90°$. Solid (dashed) lines represent the data obtained by increasing (decreasing) $B_{\perp }$ for different temperatures. The curves are offset by $200\Omega$ for clarity. The inset represents the data for $\phi =0°$ obtained at $T=50\mathrm{mK}$.

Figure 3

(a) Excess resistivity for $\phi =0°$ at different temperatures from 0.30 K to 0.75 K (from top to bottom) in steps of 0.05 K. (b) Peak positions determined by a fit to a single Gaussian function (solid circles) or a double Gaussian function (open circles). For low temperatures ($T<0.25\mathrm{K}$), where the hysteresis was observed, the mean values are plotted. Dashed straight lines represent least-squares fits to the double peaks. The right axis indicates the pseudospin Zeeman field $b=(\hslash e{B}_{\perp }/m^{*}-g^{*}{\mu }_B{B}_{\mathrm{tot}})/2$ (see text).

Figure 4

Current-voltage characteristics at $b=0$ and $\nu =4.0$ for $\phi =0°$. The temperatures are (from top to bottom) 0.372, 0.433, 0.491, 0.554, 0.641, and 0.775 K. The inset shows a possible relationship between the local electric field and current density.