Tossup
In a cubic lattice, a BEC can undergo a phase transition between a superfluid and these materials when the ratio of U to J exceeds 36. Symmetry classes denoted “A” correspond to a type of these materials in a so-called “periodic table” containing ten classes. These materials satisfy a criterion of “effective Bohr radius times the cube root of electron density” being less than about 0.2 to 0.4. Other materials may unexpectedly become these materials due to the Peierls distortion. The Hubbard model correctly predicts the behavior of nickel oxides acting as these materials, as first proposed by Nevill Mott. These materials lose their behavior and begin to produce a current beyond the breakdown voltage. For 10 points, name these materials with a high band gap, thus making them poor conductors of electricity. ■END■
ANSWER: insulators [accept Mott insulators or Chern insulators or Peierls insulators or topological insulators]
<MY, Physics>
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