Crystallization of heavy fermions via epitaxial strain in spinel LiVO thin film.

The mixed-valent spinel LiVO is known as the first oxide heavy-fermion system. There is a general consensus that a subtle interplay of charge, spin, and orbital degrees of freedom of correlated electrons plays a crucial role in the enhancement of quasi-particle mass, but the specific mechanism has remained yet elusive. A charge-ordering (CO) instability of V and V ions that is geometrically frustrated by the V pyrochlore sublattice from forming a long-range CO down to = 0 K has been proposed as a prime candidate for the mechanism.