  Microwave-induced resistance oscillations (MIRO) have been extensively
studied for more than a decade but, until now, have remained unique to
GaAs/AlGaAs-based 2D electron systems. Here, we report on the first observation
of MIRO in a 2D hole gas hosted in Ge/SiGe quantum well. Our findings confirm
that MIRO is a universal phenomenon and demonstrate that microwave
photoresistance can be utilized to probe the energy spectrum and the
correlation effects of 2D holes in Ge/SiGe quantum wells.
