A 1998 paper showing that two materials have this property from Gil Lonzarich’s group endorsed finding this property “at the edge of magnetic order.” Those materials are in the same class as cerium copper silicide, which was shown to have this property by Steglich et al. in 1979. In 2018, Jarillo-Herrero’s group demonstrated (15[1])this property near a Mott insulator state (15[1])in a material (-5[1])with a specific superlattice that drastically reduced the Fermi velocity. It’s not antiferromagnetism, but Anderson proposed an explanation for this property (15[1])in terms of resonating (15[1])(*) valence bonds, in which superexchange (10[1])through intermediate atoms provided coupling between spins. That account was devised for a system with d-wave symmetry arising from (10[1])planes (10[1])of copper and oxygen atoms. For 10 points, (10[2])the BCS (10[1])theory (10[1])of Cooper (10[1])pairs provides the “conventional” (10[1])explanation (10[1])for the behavior of what property? ■END■ (10[1])