Magnetoresistivity and Acoustoelectronic Effects in a Tilted Magnetic Field in $p$-Si/SiGe/Si Structures with an Anisotropic $g$ Factor

Magnetoresistivity ${\rho }_{xx}$ and ${\rho }_{xy}$ and the acoustoelectronic effects are measured in $p$-Si/SiGe/Si with an impurity concentration $p$ = 2 $\times$ 10${}^{11}$ cm${}^{-2}$ in the temperature range 0.3-2.0 K and an tilted magnetic field up to 18 T. The dependence of the effective $g$-factor on the angle of magnetic field tilt $\theta$ to the normal to the plane of a two dimensional $p$-Si/SiGe/Si channel is determined. A first order ferromagnet-paramagnet phase transition is observed in the magnetic fields corresponding to a filling factor $\nu$ = 2 at $\theta \approx$ 59${}^{\text{o}}$-60${}^{\text{o}}$.