Hund electronic correlation in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi>Ni</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>7</mml:mn></mml:msub></mml:mrow></mml:math> under high pressure
Zhenfeng Ouyang, Jiaming Wang, Jingxuan Wang, Rong-Qiang He, Li Huang, Zhong-Yi Lu
Abstract
By means of density functional theory plus dynamical mean-field theory, we investigate the correlated electronic structures of ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ under high pressure. Our calculations show that ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ is a multiorbital Hund metal. Both the $3{d}_{{z}^{2}}$ and $3{d}_{{x}^{2}\ensuremath{-}{y}^{2}}$ 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 spin-orbital 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 ${\mathrm{La}}_{3}{\mathrm{Ni}}_{2}{\mathrm{O}}_{7}$ under high pressure.