Low-temperature magnetic spectroscopy with a dc SQUID

New magneto-optical methods combining integrated dc superconducting quantum interference device and fiber optic technology have allowed energy- and polarization-dependent magnetization measurements to be made on a 10-μm-diam sample of Cd1-xMnxTe. Direct optically induced magnetization data probe the energetics of magnetic polaron formation and reveal the ultimate spin orientation with respect to the incident photon angular momentum.