Spin-orbital frustration in pyrochlores A2Mo2O7

Abstract

Electronic and magnetic properties of molybdenum pyrochlores A2Mo2O7 are studied by the fully relativistic density-functional theory plus on-site repulsion (U) method, with focusing on the spin-glass insulating material Y2Mo2O7. We find that the system exhibits peculiar competition in energy between different magnetic states in the large-U insulating region. The magnetic competition cannot be explained by the conventional picture based on the geometrical frustration of isotropic Heisenberg antiferromagnetic exchange interactions. Through an analysis by using a generalized spin model, we find that the effective spin interactions are distinct from the simple Heisenberg form and strongly anisotropic in spin space. We also reveal that they give rise to keen competition between antiferromagnetic and ferromagnetic states. The complex form of the magnetic interactions indicates a crucial role of the orbital degree of freedom. Analyzing a three-orbital Hubbard model, we clarify that the magnetic competition is tightly connected with orbital frustration in the 4d2 electronic configuration through the spin-orbital interplay. The results challenge the conventional picture of the spin-glass behavior that attributes the origin to the geometrical frustration of purely antiferromagnetic exchange interactions.

8 pages, 6 figures (accepted for publication as a regular article in PRB)

References in corpus (5)

• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Spin Freezing in Geometrically Frustrated Antiferromagnets with Weak Disorder
• Liquid-like correlations in single crystalline Y2Mo2O7: an unconventional spin glass
• Spin-glass transition in bond-disordered Heisenberg antiferromagnets coupled with local lattice distortions on a pyrochlore lattice
• Origin of magnetic freezing in the pyrochlore Y2Mo2O7

Cited by in corpus (17)

• Spin-orbit-entangled electronic phases in 4$d$ and 5$d$ transition-metal compounds
• Phase diagram of pyrochlore iridates: all-in-all-out magnetic ordering and non-Fermi liquid properties
• Liquid-like correlations in single crystalline Y2Mo2O7: an unconventional spin glass
• From Spin Glass to Quantum Spin Liquid Ground States in Molybdate Pyrochlores
• Orbital Dimer Model for Spin-Glass State in Y${}_2$Mo${}_2$O${}_7$
• Spin Jam: a quantum-fluctuation-induced glassy state of a frustrated magnet
• Effect of magnetoelastic coupling on spin-glass behavior in Heisenberg pyrochlore antiferromagnets with bond disorder
• Spin Hamiltonian, {Order Out of a Coulomb Phase} and Pseudo-Criticality in the Highly Frustrated Pyrochlore Heisenberg Antiferromagnet FeF${}_3$}
• Spin-orbital glass transition in a model of a frustrated pyrochlore magnet without quenched disorder
• First-principles studies of spin-orbital physics in pyrochlore oxides
• Giant Magnetoelastic-Coupling Driven Spin-Lattice Liquid State in Molybdate Pyrochlores
• Stability of the Weyl-semimetal phase on the pyrochlore lattice
• Amorphous ferromagnetism and re-entrant magnetic glassiness in Sm${}_2$Mo${}_2$O${}_7$: new insights into the electronic phase diagram of pyrochlore molybdates
• Stripe order and magnetic anisotropy in the $S=1$ antiferromagnet BaMoP${}_2$O${}_8$
• Metal-insulator transitions in pyrochlore oxides
• Mott transition and anomalous resistive state in the pyrochlore molybdates
• Ab initio determination of magnetic ground state of pyrochlore Y${}_2$Mn${}_2$O${}_7$