Can you major and minor in graduate school?

Lets say I have a degree in physics. I want to do research pertaining to engineering, but I don't want to do engineering in particular. I want a Ph.D in physics. Could I get a Ph.D in physics, but take graduate courses in Engineering? So that I will have a good foundation in that field? And don't say you can't go from physics to engineering, because I know people that went from physics to Aerospace Engineering and does research in Biomedical Engineering. Since I got that cleared, can you "major and minor" in graduate school?