Theory of the evolution of magnetic order in Fe${}_{1+y}$Te compounds with increasing interstitial iron

Abstract

We examine the influence of the excess of interstitial Fe on the magnetic properties of Fe${}_{1+y}$Te compounds. Because in iron chalcogenides the correlations are stronger than in the iron arsenides, we assume in our model that some of the Fe orbitals give rise to localized magnetic moments. These moments interact with each other via exchange interactions as well as phonon-mediated biquadratic interactions that favor a collinear double-stripe state, corresponding to the ordering vectors $\left(\pm \pi /2,\pm \pi /2\right)$. The remaining Fe orbitals are assumed to be itinerant, giving rise to the first-principle derived Fermi surface displaying nesting features at momenta $\left(\pi ,0\right)/\left(0,\pi \right)$. Increasing the amount of itinerant electrons due to excess Fe, $y$, leads to changes in the Fermi surface and to the suppression of its nesting properties. As a result, due to the Hund's coupling between the itinerant and localized moments, increasing $y$ leads to modifications in the local moments' exchange interactions via the multi-orbital generalization of the long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. By numerically computing the RKKY corrections and minimizing the resulting effective exchange Hamiltonian, we find, in general, that the excess electrons introduced in the system change the classical magnetic ground state from a double-stripe state to an incommensurate spiral, consistent with the experimental observations. We show that these results can be understood as a result of the suppression of magnetic spectral weight of the itinerant electrons at momenta $\left(\pi ,0\right)/\left(0,\pi \right)$, combined with the transfer of broad magnetic spectral weight from large to small momenta, promoted by the introduction of excess Fe.

13 pages, 8 figures

References in corpus (21)

• Near-degeneracy of several pairing channels in multiorbital models for the Fe-pnictides
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• Magnetism and its microscopic origin in iron-based high-temperature superconductors
• Coherence-incoherence crossover in the normal state of iron-oxypnictides and importance of the Hund's rule coupling
• Spin-orbital frustrations and anomalous metallic state in iron-pnictide superconductors
• Bi-collinear antiferromagnetic order in the tetragonal $\alpha$-FeTe
• From (pi, 0) magnetic order to superconductivity with (pi, pi) magnetic resonance in Fe1.02(Te1-xSex)
• Fermi surface topology and low-lying quasiparticle dynamics of parent Fe${}_{1+x}$Te/Se Superconductor by orbital-polarization resolved ARPES
• Unified Picture for Magnetic Correlations in Iron-Based Superconductors
• Importance of Fermi surface topology for high temperature superconductivity in electron-doped iron arsenic superconductors
• Pairing symmetry in a two-orbital Hubbard model on a square lattice
• Spin waves in the $(\pi ,0)$ magnetically ordered iron chalcogenide Fe${}_{1.05}$Te
• Doping Driven ($\pi ,0$) Nesting and Magnetic Properties of Fe${}_{1+x}$Te Superconductors
• Nodes in the Gap Function of LaFePO, the Gap Function of the Fe(Se,Te) Systems, and the STM Signature of the s${}_{\pm }$ Pairing
• Orbital differentiation and the role of orbital ordering in the magnetic state of Fe superconductors
• First-order structural transition in the magnetically ordered phase of Fe1.13Te
• Pressure-induced phase transitions and high-pressure tetragonal phase of Fe1.08Te
• Enhancing magnetic stripe order in iron pnictides by RKKY exchange interactions
• Magnetic order in orbital models of the iron pnictides
• Evolution of the multiband RKKY interaction: Application to iron pnictides and chalcogenides
• Hidden $(\pi ,0)$ instability as an itinerant origin of bicollinear antiferromagnetism in Fe${}_{1+x}$Te

Cited by in corpus (6)

• Collective magnetic excitations of $C_4$ symmetric magnetic states in iron-based superconductors
• Pressure-induced ferromagnetism due to an anisotropic electronic topological transition in Fe1.08Te
• Stoichiometric FeTe is a Superconductor
• Enhanced low-energy magnetic excitations evidencing the Cu-induced localization in an Fe-based superconductor Fe${}_{0.98}$Te${}_{0.5}$Se${}_{0.5}$
• Acoustic lattice instabilities at the magneto-structural transition in Fe${}_{1.057(7)}$Te
• Emergent Ising degrees of freedom above double-stripe magnetism