Page 23 - Science at the nanoscale

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June 9, 2009
1.3. Examples of Interesting Nanoscience Applications
Figure 1.6.
The branched capillary structure, feeding adipose tissue in
a living mouse, is revealed with multiphoton fluorescence microscopy as
nanocrystal quantum dots circulate through the bloodstream. [From Lar-
son D. T. et al., Science 300, 1434–1436 (2003). Reprinted with permission
from AAAS.]
powerful microprocessor. These devices exploit the charge carried
by the electrons for their normal function, and they communicate
with each other through the flow of electric charges. However,
there is another important intrinsic property of electrons that has
been neglected in these devices — the spin of the electron. Spin
is a purely quantum mechanical property. We normally think of 13 ch01
the spin of an electron using the analogy of a spinning top. The
spin can be clockwise or counterclockwise in direction. In the case
of electrons, the spin could be pointing in the “up” direction or in
the “down” direction. The spin in the electron is easily influenced
by an externally applied magnetic field. Spin electronics, or spin-
tronics, refers to electrical devices that utilise the spin properties
of the electrons in addition to their electrical charge in creating
useful devices. Scientists and engineers hope to control the spin
of electrons within a spintronics device to produce useful devices.
As the spintronics device can be influenced by the presence of an
electric field, magnetic field or light, the device represents a single