Signature of Hund-Correlation in Non-Spin-Freezing Metallic Regime Studied by Dynamical Mean Field Theory : Hundness in Global Phase Diagram

Hund-correlated systems show unique feature in contrast to Hubbard-correlated systems. Previously well studied signature of Hund interaction exists only in the spin-freezing regime, namely Hund-metal, in which spin Kondo scale and orbital Kondo scale differs by order. However, the signature of Hund interaction can also exist in different phases in the global phase diagram. Experimentally, the discrepancy between the bandwidth renormalization observed by angle-resolved photoemission spectroscopy (ARPES) and heat capacity measurement in transition metal compounds arises. This can be explained by the unique feature of Hund interaction, that strong bandwidth renormalization occurs only in low-energy scale while overall conduction band doesn’t get strongly renormalized. Our study based on Dynamical Mean Field Theory resulted that this feature can be observed at any electron fillings with non-spin-freezing regime. In contrast to Hund-Metal, this can be observed at any electron occupation including half-filled systems. In this work, we suggest a new parameter that measures the degree of Hund-correlation signature in the non-spin-freezing correlated metal phases, namely the ‘Hund-Fermi-liquid-ness’. This work suggests that we can contrast the signature of the Hund correlation to the signature of Hubbard correlation and measure the Hundness in the global phase diagram for any multi-orbital strongly correlated systems including non-spin-freezing correlated metal phase.