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Noise spectroscopy of a single spin

Yishay Manassen

We have found that tunneling with a STM (scanning tunneling microscope) to a surface in the neighborhood of a single paramagnetic atom or molecule (individual magnetic dipole) in the presence of an external magnetic field results in an elevated noise at the Larmor frequency. This high frequency noise results is due to the precession of a single magnetic dipole around the field (see Figure1).

The precession frequency depends strongly on the local environment of spin center, and can be used to identify molecules under the tip on the single molecule level. Fundamental information on the single spin physics is studied in this way. Additional potential applications are in single molecule data storage and quantum information.

Steps to improve the system which are implemented in these days, such as cooling to low temperature, working in time domain and scanning the field rather than the frequency are expected to improve the sensitivity of the detection system, to enable getting more information on the single spin physics.

Figure 1 Figures 2,3: The image on the right is an image of a gold sample covered with DPPH molecule. The spectrum on the left is from the lowest molecule in the image (#31). We collaborate on this subject with a group from Italy and also with other groups around the world.

Further reading: