Toward the manipulation of a single atomic spin, we theoretically study the switching of a localized quantum spin induced by spin injection. The system consists of electrode/spin quantum dot/electode junctions, in which the left electrode (right electrode) has conduction electrons with up spin (with down spin), and the dot has the localized quantum spin S = (Sx, S y, Sz). This S has a uniaxial anisotropic energy, -|D|S2z, which shows the bistable potential between S z = -S and S, with D being an anisotropy constant. Furthermore, S interacts with the atomic vibration. For the initial state of Sz = -S, we consider a situation in which up spin electrons exhibit the spin-flip tunneling from the left electrode to the right one through an exchange interaction between the electron spin and S. We obtain the time dependence of the current, the expectation value of Sz, and that of the vibration quantum number using the master equation approach, in which a parameter related to the spin relaxation time, τ, is taken into account. On the basis of recent experimental results about an Fe atom on CuN surface [C. F. Hir-jibehedin et al., Science 317, 1197 (2007)], we apply this theory to systems of S=2. As results, systems exhibit the switching or nonswitching depending on τ (≠ ∞) and the vibration energy within a period of 5 ns, while systems of τ = ∞ bring about the switching. The switching times are evaluated to be in the range of 0.44 ns - 3.8 ns.
|Number of pages||6|
|Journal||Physica Status Solidi (C) Current Topics in Solid State Physics|
|Publication status||Published - 2009 Dec 7|
|Event||9th International Conference Trends in Nanotechnology, TNT2008 - Oviedo, Spain|
Duration: 2008 Sep 1 → 2008 Sep 5
ASJC Scopus subject areas
- Condensed Matter Physics