Hund electronic correlation in La 3 Ni 2 O 7 under high pressure

By means of density functional theory plus dynamical mean-field theory, we investigate the correlated electronic structures of La 3 Ni 2 O 7 under high pressure. Our calculations show that La 3 Ni 2 O 7 is a multiorbital Hund metal. Both the 3 d z 2 and 3 d x 2 - y 2 orbitals of Ni are close to being half filled and contribute the bands crossing the Fermi level. Band renormalization and orbital selective electronic correlation are observed. Through imaginary-time correlation functions, the discovery of high -spin configuration, spin-frozen phase, and spinorbital separation shows that the system is in a frozen moment phase at high temperatures above 290 K and is a Fermi liquid at low temperatures, which is further confirmed by the calculated spin, orbital, and charge susceptibilities under high temperatures. Our paper uncovers Hundness in La 3 Ni 2 O 7 under high pressure.