Microwave-induced resistance oscillations in tilted magnetic fields
  We have studied the effect of an in-plane magnetic field on microwave-induced resistance oscillations in a high mobility two-dimensional electron system. We have found that the oscillation amplitude decays exponentially with an in-plane component of the magnetic field $B_\parallel$. While these findings cannot be accounted for by existing theories, our analysis suggests that the decay can be explained by a $B_\parallel$-induced correction to the quantum scattering rate, which is quadratic in $B_\parallel$. 
A. Bogan, A. T. Hatke, S. A. Studenikin, A. Sachrajda, M. A. Zudov, L.   N. Pfeiffer, K. W. West
cond-mat.mes-hall