Theory of Single Spin Detection with STM
A. V. Balatsky
and I. Martin
Received September 18, 2002; accepted December 19, 2002
We propose a mechanism for detection of a single spin center on a non-magnetic
substrate. In the detection scheme, the STM tunnel current is correlated with the spin
orientation. In the presence of magnetic ﬁeld, the spin precesses and the tunnel
current is modulated at the Larmor frequency. The mechanism relies on the eﬀective
spin-orbit interaction between the injected unpolarized STM current and the local
spin center, which leads to the nodal structure of the spatial signal proﬁle. Based on
the proposed mechanism, the strongest spin-related signal can be expected for the
systems with large spin-orbit coupling and low carrier concentration.
KEY WORDS: Single spin; precession; STM; spin-orbit; coupling.
PACS: 74.40.Gk; 72.70.+m; 73.63.Kv; 85.65.+h.
There is no fundamental principle that precludes the single spin
measurement. Possibility of a single spin observation is therefore a question
of spatial and temporal resolution. The standard electron spin measurement
technique—electron spin resonance—is limited to a macroscopic number of
the state-of-the-art magnetic resonance
force microscopy has recently achieved the resolution of about 100 fully
polarized electron spins.
It has already been shown that optically induced
ESR of a single spin is possible.
There are proposals for the spin detection
using single electron transistor and spin-polarized current.
In this letter
we propose the theoretical basis for the new spin-detection technique—
electron spin precession scanning tunneling microscopy (ESP-STM)—cap-
able of single spin detection.
The applications of single spin detection and manipulation range from
the study of strongly correlated systems, to nanotechnology, to quantum
1570-0755/02/1000-0355/0 # 2003 Plenum Publishing Corporation
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545
To whom correspondence should be addressed. E-mail: firstname.lastname@example.org
Quantum Information Processing, Vol. 1, No. 5, October 2002 (# 2003)