Condensed Matter Physics Seminar
2 p.m., Thursday, March 11, 2004
Room 1201, Physics Building
Noise spectroscopy of a single spin
Alexander V. Balatsky
(Los Alamos National Laboratory)
Abstract: Recent scanning tunneling microscope (STM) experiments on
magnetic centers on a surface demonstrate that one can get a spatially localized
current signal directly related to a precessing spin. I will discuss possible
mechanisms that allows tunneling current couple to the spin degrees of freedom.
Important feature of these experiments is that signal is observed in the noise
of the tunneling current. I will argue that this experiment is another example,
among many, of the noise spectroscopy. A possible extension of this technique
where one considers the coupling between ac Josephson current and a single spin
in the junction is proposed . I will argue that in an external magnetic
field, resulting in a Larmor precession of a spin, spin is nutating at the
Josephson frequency. Sidebands at sum and difference of Larmor and Josephson
frequencies are formed. Noise spectroscopy is an emergent technique that might
be applied to surface magnetism studies and to quantum information.
 Jian-Xin Zhu, Z. Nussinov, A. Shnirman and A. V. Balatsky, "Novel Spin
Dynamics in a Josephson Junction", PRL to be published, cond-mat/0306710.
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