We present a discussion of the present state of experimental and theoretical investigations of a new class of metallic systems based on f-shell elements: the class of nonmagnetic Kondo lattices, in which the low-temperature density of electron states at the Fermi level is 100--1000 times larger than in normal metals, as a consequence of the generation of an astonishingly narrow ($\sim$10$^\circ$K) Abrikosov--Suhl resonance of gigantic amplitude near the Fermi level. This resonance is related to the presence of quasiparticles with effective masses $m^*\sim$(10$^2$--10$^3$)$m_0$ -- ``heavy fermions''. We show that the overwhelming majority of ``heavy fermion systems'' are in fact nonmagnetic Kondo lattices. We analyze the unusual properties of heavy-fermion superconductors, and point out the nontrivial nature of superconductivity in these systems.

@article{Moshchalkov:1986,
	author = {V. V. Moshchalkov and N. B. Brandt},
	title = {Nonmagnetic Kondo lattices},
	publisher = {Physics-Uspekhi},
	year = {1986},
	journal = {Phys. Usp.},
	volume = {29},
	number = {8},
	pages = {725-724},
	url = {https://ufn.ru/en/articles/1986/8/a/},
	doi = {10.1070/PU1986v029n08ABEH003480}
}