In-plane magnetic field dependence of cyclotron relaxation time in a Si two-dimensional electron system

Cyclotron resonance of two-dimensional electrons is studied for a high-mobility Si/SiGe quantum well in the presence of an in-plane magnetic field, which induces spin polarization. The relaxation time ${\tau }_{\mathrm{CR}}$ shows a negative in-plane magnetic-field dependence, which is similar to that of the transport scattering time ${\tau }_t$ obtained from dc resistivity. The resonance magnetic field shows an unexpected negative shift with increasing in-plane magnetic field.

Figure 1

Resistivity $\rho$ as a function of $B_{\parallel }$ at $B_{\perp }=0$ for different temperatures. Calculated values of $B_{\parallel }$ for $P=0.5$ are indicated by arrows.

Figure 2

(a) $B_{\perp }$ dependence of the longitudinal resistivity ${\rho }_{xx}$, with (solid curve) and without (dashed curve) electromagnetic-wave excitation. The in-plane magnetic field and the lattice temperature are fixed at $B_{\parallel }=3.0$ T and $T_{\mathrm{L}}=1.7$ K, respectively. (b) CR trace deduced from the electron temperature $T_e$. The energy absorption per unit area is assumed to be proportional to $T_e^5-T_{\mathrm{L}}^5$. The corresponding temperature difference, $\Delta T=T_e-T_{\mathrm{L}}$, is indicated on the right axis.

Figure 3

(a) Scattering times ${\tau }_t$ and ${\tau }_{\mathrm{CR}}$ at $T=1.7$ K as a function of $B_{\parallel }$. The corresponding spin polarization is indicated on the upper axis. (b) The resonance magnetic field $B_{\mathrm{CR}}$ vs $B_{\parallel }$. The dotted line represents $B_{\mathrm{CR}}=0.19m_e\omega /e$.