Magnetoresistivity in a Tilted Magnetic Field in p-Si/SiGe/Si Heterostructures with an Anisotropic g-Factor: Part II

The magnetoresistance components ${\rho }_{xx}$ and ${\rho }_{xy}$ were measured in two p-Si/SiGe/Si quantum wells that have an anisotropic g-factor in a tilted magnetic field as a function of temperature, field and tilt angle. Activation energy measurements demonstrate the existence of a ferromagnetic-paramagnetic (F-P) transition for a sample with a hole density of $p$=2$\times {10}^{11}$,cm${}^{-2}$. This transition is due to crossing of the 0$\uparrow$ and 1$\downarrow$ Landau levels. However, in another sample, with $p$=7.2$\times {10}^{10}$,cm${}^{-2}$, the 0$\uparrow$ and 1$\downarrow$ Landau levels coincide for angles $\mathrm{\Theta }$=0-70${}^{\text{o}}$. Only for $\mathrm{\Theta }$ > 70${}^{\text{o}}$ do the levels start to diverge which, in turn, results in the energy gap opening.