Itinerant and localized magnetism on the triangular lattice: sodium rich phases of Na${}_x$CoO${}_2$

Abstract

We study the interplay between correlation, itinerant ferromagnetism and local moment formation on the electron doped triangular lattice of sodium cobaltates Na${}_x$CoO${}_2$. We find that strong correlation renormalizes the Stoner criterion and stabilizes the paramagnetic state for $x<x_c\simeq 0.67$. For $x>x_c$, ferromagnetic (FM) order emerges. The enhanced Na dopant potential fluctuations play a crucial role in the sodium rich phases and lead to an inhomogeneous FM state, exhibiting nonmagnetic Co${}^{3+}$ patches, antiferromagnetic (AF) correlated regions, and FM clusters with AF domains. Hole doping the band insulator at x=1 leads to the formation of local moments near the Na vacancies and AF correlated magnetic clusters. We explain recent observations by neutron, $\mu$SR, and NMR experiments on the evolution of the magnetic properties in the sodium rich phases.

revtex4 file, 5 pages, 3 figures, published version

References in corpus (25)

• Charge-ordering, commensurability and metallicity in the phase diagram of layered Na(x)CoO(2)
• Large enhancement of the thermopower in Na${}_x$CoO${}_2$ at high Na doping
• Fermi surface and quasiparticle dynamics of Na(x)CoO2 {x=0.7} investigated by Angle-Resolved Photoemission Spectroscopy
• Coupling between electronic and structural degrees of freedom in the triangular lattice conductor NaxCoO2
• Magnetic ordering and spin waves in $\mathbf{N}{\mathbf{a}}_{0.82}\mathbf{Co}{\mathbf{O}}_2$
• Fermi surface evolution and Luttinger theorem in Na${}_x$CoO${}_2$: a systematic photoemission study
• ARPES on Na${}_{0.6}$CoO${}_2$: Fermi surface, extended flat dispersion, and unusual band splitting
• Ferromagnetic in-plane spin fluctuations in NaxCoO2 observed by neutron inelastic scattering
• Possible effects of charge frustration in Na${}_x$CoO${}_2$: bandwidth suppression, charge orders and resurrected RVB superconductivity
• Ferromagnetism, paramagnetism and a Curie-Weiss metal in an electron doped Hubbard model on a triangular lattice
• Electron correlation and Fermi surface topology of Na${}_x$CoO${}_2$
• Neutron scattering study of novel magnetic order in Na0.5CoO2
• Charge ordering and magneto-polarons in Na${}_{0.82}$CoO${}_2$
• Low-lying quasiparticle states and hidden collective charge instabilities in parent cobaltate superconductors (NaxCoO2)
• NMR study of the magnetic and metal-insulator transitions in Na0.5CoO2: a nesting scenario
• Kinetic Antiferromagnetism in the Triangular Lattice
• Complete d-Band Dispersion and the Mobile Fermion Scale in NaxCoO2
• Na Induced Correlations in Na${}_x$CoO${}_2$
• The Fermi surface of Na${}_x$CoO${}_2$
• Effect of Dynamical Coulomb Correlations on the Fermi Surface of Na_0.3CoO_2
• Strong Correlations Produce the Curie-Weiss Phase of Na${}_x$CoO${}_2$
• Magnetic properties of spin-orbital polarons in lightly doped cobaltates
• Charge and spin order on the triangular lattice -- Na${}_x$CoO${}_2$ at $x=0.5$
• Itinerant in-plane magnetic fluctuations and many-body correlations in Na${}_x$CoO${}_2$
• Electronic structure and Fermi surface tolopogy of Na${}_x$CoO${}_2$

Cited by in corpus (8)

• Spin correlations and cobalt charge states: A new phase diagram of sodium cobaltates
• Electronic texture of the thermoelectric oxide Na0.75CoO2
• Na atomic order, Co charge disproportionation and magnetism in Na${}_x$CoO${}_2$ for large Na contents
• Correlation effects on the doped triangular lattice in view of the physics of sodium-rich Na${}_x$CoO${}_2$
• Electron-phonon interaction in the lamellar cobaltate Na${}_x$CoO${}_2$
• Considerable non-local electronic correlations in strongly doped Na${}_x$CoO${}_2$
• Mott and Wigner-Mott transitions in doped correlated electron systems: effects of superlattice potential and inter-site correlation
• Evidence for Oxygen Holes due to d-p Rehybridization in Thermoelectric Sr_{1-x}Rh_{2}O_{4}