residual entropy

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  • Info Residual entropy is the difference in entropy between a non-equilibrium state and crystal state of a substance close to absolute zero. more...
  • A great deal of research has thus been undertaken into finding other systems that exhibit residual entropy.
  • Spin ice materials therefore exhibit the same residual entropy properties as water ice.
  • Thus systems that can take multiple configurations at or near absolute zero are said to have residual entropy.
  • The constant value is called the residual entropy of the system.
  • One of the first examples of residual entropy was pointed out by Pauling to describe water ice.
  • Spin ices show low-temperature properties, residual entropy in particular, closely related to those of crystalline water ice.
  • The constant value (not necessarily zero) is called the residual entropy of the system.
  • Although water ice was the first material for which residual entropy was proposed, it is generally very difficult to prepare pure defect-free crystals of water ice for studying.
  • These have residual entropy, because the atom-by-atom microscopic structure can be arranged in a huge number of different ways across a macroscopic system.
  • That is, even upon cooling to zero temperature, water ice is expected to have residual entropy, i.e., intrinsic randomness.
  • This residual entropy disappears when the kinetic barriers to transitioning to one ground state are overcome.
  • Additionally, the interaction of a magnetic field with the spins in a spin ice material make spin ice materials much better materials for examining residual entropy than water ice.
  • The first such model was introduced by Linus Pauling in 1935 to account for the residual entropy of water ice.
  • Some crystals form defects which causes a residual entropy.
  • Geometrically frustrated systems in particular often exhibit residual entropy.
  • One of the interesting properties of geometrically frustrated magnetic materials such as spin ice is that the level of residual entropy can be controlled by the application of an external magnetic field.
  • This material is thus analogous to water ice, with the exception that the spins on the corners of the tetrahedra can point into or out of the tetrahedra, thereby producing the same 2-in, 2-out rule as in water ice, and therefore the same residual entropy.
  • The ice rule was introduced by Linus Pauling in 1935 to account for the residual entropy of ice that had been measured by William F. Giauque and J. W. Stout.
  • Currently the spin ice model has been approximately realized by real materials, most notably the rare earth pyrochlores Ho 2 Ti 2 O 7, Dy 2 Ti 2 O 7, and Ho 2 Sn 2 O 7, These materials all show nonzero residual entropy at low temperature.