Can Orbital-Selective Néel Transitions Survive Strong Nonlocal Electronic Correlations?

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• Correlated electron materials exhibit spin- or orbital-selective behaviors with potential for spintronics and orbitronics.
• Orbital-selective Mott states arise from strong Coulomb correlations, with coexisting localized and itinerant electrons.

Purpose of the Study:

• Investigate the realization of orbital-selective Néel transitions (OSNT).
• Identify conditions for stabilizing OSNT, particularly the decoupling of magnetic fluctuations.

Main Methods:

• Utilized two-orbital calculations for a Hubbard model with varying bandwidths.
• Analyzed the influence of Hund's exchange coupling on magnetic fluctuations.

Main Results:

• OSNT stabilization requires the absence of Hund's exchange coupling.
• The OSNT was observed across weak to strong coupling regimes.
• In weak coupling, a Slater mechanism favors the narrow orbital; in strong coupling, a Heisenberg mechanism favors the wide orbital.
• A nontrivial intermediate coupling regime shows the Slater mechanism favoring the wide orbital.

Conclusions:

• Orbital-selective Néel ordering is achievable under specific conditions, particularly without Hund's coupling.
• The study provides insights into the mechanisms governing OSNT in different coupling regimes.
• Suggests strategies for discovering OSNT in real materials for future spin-orbitronics applications.