Spin waves in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mi>J</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mi>a</mml:mi></mml:mrow></mml:msub><mml:mtext>−</mml:mtext><mml:msub><mml:mi>J</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mi>b</mml:mi></mml:mrow></mml:msub><mml:mtext>−</mml:mtext><mml:msub><mml:mi>J</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math>orthorhombic square-lattice Heisenberg models: Application to iron pnictide materials

Applegate, Ryan; Oitmaa, J.; Singh, Rajiv R. P.

doi:10.1103/physrevb.81.024505

Cited by 38 publications

(40 citation statements)

References 39 publications

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“…In previous observations of electronic nematic phases in different materials, there is usually a symmetry breaking field present, such as an external magnetic field, uniaxial pressure, or an orthorhombic crystalline lattice [12][13][14][15][16][17] , which is not the case here. The observation of a short-range spin nematic phase in the tetragonal state of BaFe 2 As 2 reveals the presence of strong spin-orbital coupling at temperatures above T N [17][18][19][20][21][22][23][24]29].…”

Section: Discussionmentioning

confidence: 99%

“…These results provide compelling evidence for a nematic spin fluid that breaks the tetragonal C 4 symmetry of the underlying crystalline lattice and spontaneously forms without the need for uniaxial pressure. Moreover, we suggest that this spin anisotropy causes a splitting of the d xz and d yz orbital bands in the tetragonal phase [18][19][20][21][22][23][24] , which in turn leads to the orthorhombic lattice distortion and electronic anisotropy.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, it is unclear whether electronic anisotropy can exist in a truly tetragonal phase without an external driving field. A decisive answer to this question will not only reveal the microscopic origin of the lattice and magnetic transitions in iron arsenides, but will also determine the importance of electron correlations and orbital degrees of freedom in these materials [18][19][20][21][22][23][24] .…”

Section: Introductionmentioning

confidence: 99%

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Nematic spin fluid in the tetragonal phase of BaFe2As2

et al. 2011

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Abstract:We use inelastic neutron scattering to study spin waves below and above T N in ironarsenide BaFe 2 As 2 . In the low-temperature orthorhombic phase, we find highly anisotropic spin waves with a large damping along the antiferromagnetic (AF) aaxis direction. On warming the system to the paramagnetic tetragonal phase, the low-energy spin waves evolve into quasi-elastic excitations, while the anisotropic spin excitations near the zone boundary persist. These results strongly suggest the presence of a spin nematic fluid in the tetragonal phase of BaFe 2 As 2 , which may cause the electronic and orbital anisotropy observed in these materials.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Nematic spin fluid in the tetragonal phase of BaFe2As2

et al. 2011

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“…Some systems are believed to possess good nesting properties [3][4][5], while some are not [6,11]. Also there have been many theories that emphasize the role of local Fe 3d electrons [12][13][14][15].…”

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confidence: 99%

Orbital Selective Fermi Surface Shifts and Mechanism of HighTcSuperconductivity in CorrelatedAFeAs(A=Li, Na)

Lee

Kim

et al. 2012

Phys. Rev. Lett.

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Based on the dynamical mean field theory (DMFT) and angle resolved photoemission spectroscopy (ARPES), we have investigated the mechanism of high Tc superconductivity in stoichiometric LiFeAs. The calculated spectrum is in excellent agreement with the observed ARPES measurement. The Fermi surface (FS) nesting, which is predicted in the conventional density functional theory method, is suppressed due to the orbital-dependent correlation effect with the DMFT method. We have shown that such marginal breakdown of the FS nesting is an essential condition to the spin-fluctuation mediated superconductivity, while the good FS nesting in NaFeAs induces a spin density wave ground state. Our results indicate that fully charge self-consistent description of the correlation effect is crucial in the description of the FS nesting-driven instabilities.

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“…This set of parameters corresponds to the neutron scattering observation that the spin-wave spectra is better fit with an AFM exchange along one direction and a weak FM exchange along the other. 73 The latter could arise from double exchange 57 or from the orbital geometries. 55 But, its sign or magnitude is not crucial for the phase transitions we report here.…”

Section: II Spin-orbital Modelmentioning

confidence: 99%

Phase transitions in spin-orbital models with spin-space anisotropies for iron pnictides: Monte Carlo simulations

et al. 2012

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The common phase diagrams of superconducting iron pnictides show interesting material specificities in the structural and magnetic phase transitions. In some cases the two transitions are separate and second order, while in others they appear to happen concomitantly as a single first order transition. We explore these differences using Monte Carlo simulations of a two-dimensional Hamiltonian with coupled Heisenberg-spin and Ising-orbital degrees of freedom. In this spin-orbital model, the finite-temperature orbital-ordering transition results in a tetragonal-to-orthorhombic symmetry reduction and is associated with the structural transition in the iron-pnictide materials. With a zero or very small spin space anisotropy, the magnetic transition separates from the orbital one in temperature, and the orbital transition is found to be in the Ising universality class. With increasing anisotropy, the two transitions rapidly merge together and tend to become weakly first order. We also study the case of a single-ion anisotropy and propose that the preferred spin-orientation along the antiferromagnetic direction in these materials is driven by orbital order.

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Spin waves inJ1a−J1b−J2orthorhombic square-lattice Heisenberg models: Application to iron pnictide materials

Cited by 38 publications

References 39 publications

Nematic spin fluid in the tetragonal phase of BaFe2As2

Nematic spin fluid in the tetragonal phase of BaFe2As2

Orbital Selective Fermi Surface Shifts and Mechanism of HighTcSuperconductivity in CorrelatedAFeAs(A=Li, Na)

Phase transitions in spin-orbital models with spin-space anisotropies for iron pnictides: Monte Carlo simulations

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