The search for room-temperature superconductivity was motivated not only by the desire for resistance-free current in order to reduce energy costs, but was also an academic challenge, since until the mid-1970s, 30 K seemed to be the temperature limit for superconductivity. It should be recalled that superconductivity was discovered in 1911; it took nearly 60 years to achieve 25 K superconductivity. Only in 1957 were Bardeen, Cooper, and Schrieffer(BCS) able to explain this phenomenon in terms of the interaction of electrons with lattice vibrations (phonons), which gives rise to an attractive channel for electron pairing. Since the phonon-mediated pairing mechanism imposes constraints on the maximum superconducting transition temperature, Tc, via the Eliashberg theory, novel mechanisms for the pairing have been proposed in terms of, for example, excitonic pairing, electronic mechanisms, and spin fluctuations, in order to achieve higher values of the transition temperature. A different approach was followed by Bednorz and Müller who considered lattice-mediated pairing, not by incorporating classical lattice vibrations, but rather in terms of the Jahn–Teller polaron mechanis, which does not entail limits on Tc.