Physicists have modeled the behavior of strange metals

American
physicists have created a lattice model in which they were able to reproduce the real temperature
the dependence of the resistivity of strange metals. Unlike conventional
metals, in their strange counterparts, which is also called Planck, resistance
proportional to temperature close to absolute zero. To achieve this phenomenon, the researchers were able to
by modeling transitions between the three States of matter: spin glass Fermi liquid and a Mott insulator. With the development of computational
methods the model created will allow a better understanding of the physics of strange metals and
to come close to describing high-temperature superconductivity, write the authors in the journal Proceedings of the National Academy of Sciences.

Name
strange metals already in itself speaks about their level of knowledge. A state of matter
can be called intermediate between the conductor and the dielectric: it is an electron
already free, but still significantly less mobile than in the normal metal.
At the same time in the Planck metals is the maximum permissible quantum
mechanics the rate of energy dissipation. This behavior of conducting electrons
leads to an unusual temperature dependence of the resistivity near absolute
zero, it is proportional to temperature, while that of conventional metals, such as
a rule, after the superconducting phase is a more dramatic increase in resistance.

Especially interesting
the linear dependence of resistivity on temperature is due to the fact that it is typical
for cuprate superconductors — substances with extremely high temperatures of superconductivity at
normal pressure, which are also strange metals. There are a number of statistical models, which in the first
approximation describing this behavior of the resistivity, but the scientists for a long time
not been able to create a fairly complete microscopic theory. Phenomenology
motivated by cuprates and the birth of theories on quantum spin liquid (about
what it is, we wrote in a material “Quantum alphabet:
Spin liquid”). Since the special behavior of strange metals makes itself
know close to absolute zero, physicists began to study the principal status (fixed
state at zero energy) of quantum systems in the framework of such theories. However, though such an approach and demonstrated the temperature dependence
resistivity, the main state of matter in these models was
spin glass and not metal Planck.

Spin
glass, in turn, is a class of substances in which individual magnetic moments
the atoms are arranged randomly. From the name of a parallel with conventional glass, in
which distributed amorphous atoms themselves, included in its composition. However, the nature of
amorphous magnetic moments in spin glass is much harder and there is
because RKKY-exchange interactionthat takes place between the magnetic
ions through the collectivized conduction electrons. On phase diagrams
spin glass often coexists with a Fermi liquid — low temperature quantum liquid of interacting fermions
(particles with half-integer spin) with a PA
invariance. With the help of the theory of Fermi liquid describes the behavior
electrons in ordinary metals at low temperatures.

Now Peter Cha (Peter
Cha) from Cornell University and his colleagues have determined that electrons in strange metals
by their nature, are something intermediate between electrons in
spin glass and in the Fermi liquid. It turned out that between these two
States there is a quantum critical point (the critical point between
two States of a substance at absolute zero temperature), in which specific
the resistance in a substance is proportional to temperature. With increasing
temperature characteristic of strange metals the temperature dependence is found in substances, located on the phase diagram in the region between the Fermi liquid and Mott isolationi.
The last are crystalline substances with a dielectric
properties that could be conduits according to the conventional theory
the electrical conductivity, but are actually insulators for preventing
the movement of charge is the Coulomb repulsion between the electrons.

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