(Used to be they just kept stuff secret; now they patent some of it.)
United States Patent Patent Number: 5264794 Date of Patent: 23 Nov 1993
Method of measuring magnetic fields on magnetically recorded media using a scanning tunneling microscope and magnetic probe
Inventor(s): Burke, Edward R., Silver Spring, MD, United States Mayergoyz, Isaak D., Rockville, MD, United States Adly, Amr A., Hyattsville, MD, United States Gomez, Romel D., Beltsville, MD, United States Assignee: The United States of America as represented by the Director, National Security Agency, Washington, DC, United States (U.S. government)
That isn't NSA research, it was merely sponsored by the NSA. Those are all university people who have published their work on MFSTM in journals, papers, and theses (I used some of it in my paper at the Usenix Security Symposium, and two of the images in my talk were provided by one of Mel Gomez' students). What the NSA is doing in this area is still classified (although I suspect the techology isn't much different from what's publicly available), in this case all they were doing was protecting their investment (just like the various PKC patents originally assigned to universities). Peter.