What is Condensed Matter Physics?
"At
each new level of complexity, entirely new properties appear,
and the understanding of these behaviors requires research
which I think is as fundamental in its nature as any other."
P.
W. Anderson, "More is different", Science 177,
393 (1972) |
The
basic aim of Condensed Matter Physics is to understand the collective
properties of large assemblies of atoms and molecules in terms of
the interactions between their component parts. The
study of matter on length scales above 1Å and energy scales
smaller than 1eV reveals how collection of many interacting degrees
of freedom exhibits novel, emergent phenomena, which are
insensitive to details of what happens at shorter length and higher
energy scales. For example, a gold atom, which is completely understood
within the Schrödinger equation, is spherical and featureless
- quite unlike the lustrous malleable and conducting metal prized
by human societies. Furthermore, the same microscopic equations
describe two different collections of 1023
molecules of H20: one might
be water and the other ice (in
crystalline or glassy phase), in which case the properties of
the two systems are completely different and the similarity between
their microscopic equations is of no practical consequence. Instead,
low-energy long-wavelength physics emerges as
a result of interactions among large number of particles.
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Crystalline
Solids |
Non-crystalline
Solids |
Quasiparticle
vs. Collective Effects |
Transport
in Nanostructures |
Thus,
a modern attitude toward Condensed Matter Physics is that the study
of collective principles that govern matter is a frontier unto itself,
complementary, yet separate to those of elementary particles physics
and cosmology. This Introductory Course is
focused on fundamental physical phenomena in (mostly) crystalline
solids, discussed in terms of the basic principles of classical
and quantum physics, where approximate picture of "quasiparticles",
such as "quasielectrons" (interacting with other electrons
through an average field) and phonons (quantized lattice vibrations),
is sufficient to capture essential physics.
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