Researchers report an insulator made of two
conductors

Ohm’s law is well-known from physics class. It states
that the resistance of a conductor and the voltage applied to it
determine how much current will flow through the conductor. The
electrons in the material—the negatively charged carriers—move in a
disordered fashion and largely independently of each other.
Physicists find it far more interesting, however, when the charge
carriers influence one another strongly enough for that simple
picture not to be correct anymore.