  The role of impurities as experimental probes in the detection of quantum
material properties is well appreciated. Here we study the effect of a single
classical magnetic impurity in trapped ultracold Fermi superfluids. Depending
on its shape and strength, a magnetic impurity can induce single or multiple
mid-gap bound states in a superfluid Fermi gas. The multiple mid-gap states
could coincide with the development of a Fulde-Ferrell-Larkin-Ovchinnikov
(FFLO) phase within the superfluid. As an analog of the Scanning Tunneling
Microscope, we propose a modified RF spectroscopic method to measure the local
density of states which can be employed to detect these states and other
quantum phases of cold atoms. A key result of our self consistent Bogoliubov-de
Gennes calculations is that a magnetic impurity can controllably induce an FFLO
state at currently accessible experimental parameters.
