Mesoscopic physics
Condensed matter physics |
---|
Mesoscopic physics is a subdiscipline of
A macroscopic electronic device, when scaled down to a meso-size, starts revealing quantum mechanical properties. For example, at the macroscopic level the
Mesoscopic physics also addresses fundamental practical problems which occur when a macroscopic object is miniaturized, as with the miniaturization of
There is no rigid definition for mesoscopic physics but the systems studied are normally in the range of 100 nm (the size of a typical
Quantum confinement effects
Electrons in bulk
The quantum confinement effect can be observed once the diameter of the particle is of the same magnitude as the wavelength of the electron's wave function.[4] When materials are this small, their electronic and optical properties deviate substantially from those of bulk materials.[5] As the material is miniaturized towards nano-scale the confining dimension naturally decreases. The characteristics are no longer averaged by bulk, and hence continuous, but are at the level of quanta and thus discrete. In other words, the energy
In addition, quantum confinement effects consist of isolated islands of electrons that may be formed at the patterned interface between two different semiconducting materials. The electrons typically are confined to disk-shaped regions termed
Because the electron energy levels of quantum dots are discrete rather than continuous, the addition or subtraction of just a few atoms to the quantum dot has the effect of altering the boundaries of the bandgap. Changing the geometry of the surface of the quantum dot also changes the bandgap energy, owing again to the small size of the dot, and the effects of quantum confinement.[6]
Interference effects
In the mesoscopic regime, scattering from defects – such as impurities – induces interference effects which modulate the flow of electrons. The experimental signature of mesoscopic interference effects is the appearance of reproducible fluctuations in physical quantities. For example, the conductance of a given specimen oscillates in an apparently random manner as a function of fluctuations in experimental parameters. However, the same pattern may be retraced if the experimental parameters are cycled back to their original values; in fact, the patterns observed are reproducible over a period of days. These are known as universal conductance fluctuations.
Time-resolved mesoscopic dynamics
Time-resolved experiments in mesoscopic dynamics: the observation and study, at nanoscales, of condensed phase dynamics such as crack formation in solids, phase separation, and rapid fluctuations in the liquid state or in biologically relevant environments; and the observation and study, at nanoscales, of the ultrafast dynamics of non-crystalline materials.[8][9]
Related
- Aharonov–Bohm nano rings– Electromagnetic quantum-mechanical effect in regions of zero magnetic and electric field
- Branched flow – Scattering phenomenon in wave dynamics
- Ballistic conduction – Movement of charge carriers with negligible scattering
- Coulomb blockade – increased resistance at small bias voltages of an electronic device comprising at least one low-capacitance tunnel junction
- Nanomaterials – Materials whose granular size lies between 1 and 100 nm
- Nanophysics– Molecular-scale artificial or biological device
- Nanotechnology – Field of science involving control of matter on atomic and (supra)molecular scales
- Persistent current – Perpetual electric current, not requiring an external power sources
- Quantum chaos – Branch of physics seeking to explain chaotic dynamical systems in terms of quantum theory
- Quantum Hall effect – Electromagnetic effect in physics
- Quantum wire – An electrically conducting wire in which quantum effects influence the transport properties
- Random matrix – Matrix-valued random variable
- Semiclassical physics – Use of both classical and quantum physics to analyze a system
- Spin–orbit interaction – Relativistic interaction in quantum physics
- Weak localization – quantum physical phenomenon
References
- S2CID 16012275.
- ^ a b c "Sci-Tech Dictionary". McGraw-Hill Dictionary of Scientific and Technical Terms. McGraw-Hill Companies, Inc. 2003.
- ^ a b c "Mesoscopic physics." McGraw-Hill Encyclopedia of Science and Technology. The McGraw-Hill Companies, Inc., 2005. Answers.com 25 Jan 2010. http://www.answers.com/topic/mesoscopic-physics-1
- OCLC 49051457.
- OCLC 32264947.
- ^ a b Quantum dots Archived 2010-02-01 at the Wayback Machine. 2008 Evident Technologies, Inc.
- S2CID 11686506.
- ^ Barty, Anton; et al. (2008-06-22). "Ultrafast single-shot diffraction imaging of nanoscale dynamics". .
- ^ "Study gains images at ultra-fast timescale" (The research appears in the online edition of the journal Nature Photonics). Science Online. Facts On File, Inc. United Press International. 2008-06-25. p. 01. Retrieved 2010-01-25.
External links
- Universiteit Leiden. Retrieved 14 June 2018.
- Harmans, C. (2003). "Mesoscopic physics: an introduction" (PDF). OpenCourseWare TU Delft. Retrieved 14 June 2018.
- Jalabert, Rodolfo A. (2016). "Mesoscopic transport and quantum chaos". S2CID 26633032.