Time-resolved scanning tunneling microscopy through tunnel distance modulation

The ability to perform time-resolved measurements of fast transient signals with a scanning tunneling microscope has been achieved through direct control of the tunneling distance on short time scales. Modulation of the tip-sample separation is provided by the use of a magnetostrictive tip driven by a local magnetic field coil. The technique offers a broadly applicable means of obtaining fast dynamical information in tunneling microscopy, and is demonstrated here on nanosecond time scales.