Magnetic and orbital order in 2D electron gases at (111) oxide surfaces and interfaces*

Recent experiments have explored two-dimensional electron gases (2DEGs) at oxide (111) surfaces and interfaces. We discuss many-body instabilities of such (111) 2DEGs, incorporating multiorbital interactions in the t_2g manifold which can induce diverse magnetic and orbital orders. Such broken symmetries may lead to electronic nematicity in transport, which could cooperate or compete with phonon mechanisms. We present an effective field theory for the interplay of magnetism and nematic charge order, and discuss implications of the nematicity for transport in (111) 2DEGs.