Fluctuation-driven topological Hund insulators

Budich, Jan Carl; Trauzettel, Björn; Sangiovanni, Giorgio

doi:10.1103/physrevb.87.235104

Cited by 84 publications

(91 citation statements)

References 59 publications

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“…In particular the approximate chiral symmetry implies that the minigap of a realistic multi-band wire almost vanishes with the increase of the parallel Zeeman field and can only be restored to experimentally accessible values by a second Zeeman field orthogonal to the wire which breaks the approximate chiral symmetry. The results here have also been recently shown to be important for Majorana flat bands in (p±ip) superconductors [34] and edge MF modes in semiconductor wires with long SO coupling lengths [35,36].…”

mentioning

confidence: 68%

Topological Invariants for Spin-Orbit Coupled Superconductor Nanowires

2012

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We show that a spin-orbit coupled semiconductor nanowire with Zeeman splitting and s-wave superconductivity is in symmetry class BDI (and not D as is commonly thought) of the topological classification of band Hamiltonians. The class BDI allows for an integer Z topological invariant equal to the number of Majorana fermion (MF) modes at each end of the quantum wire protected by the chirality symmetry (reality of the Hamiltonian). Thus it is possible for this system (and all other d = 1 models related to it by symmetry) to have an arbitrary integer number, not just 0 or 1 as is commonly assumed, of MFs localized at each end of the wire. The integer counting the number of MFs at each end reduces to 0 or 1, and the class BDI reduces to D, in the presence of terms in the Hamiltonian that break the chirality symmetry.

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confidence: 68%

Topological Invariants for Spin-Orbit Coupled Superconductor Nanowires

2012

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“…Here we connect its features as a high-spin paramagnet with the peculiar electronic structure: a half-filled e g manifold at the Fermi level which is extremely narrow and uncommonly well separated from any other band. The origin of this lies in the isotropic reduction of the hoppings in by considering also heavier elements of the Ni group and upon splitting the e g bands by heterostructuring or strain a correlation-driven band inversion can be realized, as in recent theoretical proposals for interacting topological insulators [39][40][41][42][43] .…”

Section: Nickel (Ni) In Dmentioning

confidence: 99%

Nickel-titanium double perovskite: A three-dimensional spin-1 Heisenberg antiferromagnet

2015

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The double perovskite La2NiTiO6 is identified as a three-dimensional S=1 quantum magnet. By means of Density Functional Theory we demonstrate that this material is a high-spin d-electron system deep in the Heisenberg limit and establish that its paramagnetic Mott phase persists down to low temperatures (experimental Néel temperature T N ∼ 25K) not because of frustration effects but rather for strong local fluctuations of the magnetic order parameter. Our many-body calculations on an ab initio-derived multi-orbital basis predict indeed a kinetic energy gain when entering the magnetically ordered phase. La2NiTiO6 emerges thus as a paradigmatic realization of a Hund's coupling-driven Mott insulator. Its peculiar properties may turn out to be instrumental in the ongoing chase after correlated topological states of matter.

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“…The notion of topological invariants can also been extended for an interacting system [91][92][93]. In Sec.…”

Section: B the Anisotropic Quantum Spin Hall Phasementioning

confidence: 99%

Anisotropic quantum spin Hall effect, spin-orbital textures, and the Mott transition

2013

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We investigate the interplay between topological effects and Mott physics in two dimensions on a graphene-like lattice, via a tight-binding model containing an anisotropic spin-orbit coupling on the next-nearest-neighbour links and the Hubbard interaction. We thoroughly analyze the resulting phases, namely a topological band insulator phase or anisotropic quantum Spin Hall phase until moderate interactions, a Néel and Spiral phase at large interactions in the Mott regime, as well as the formation of a spin-orbital texture in the bulk at the Mott transition. The emergent magnetic orders at large interactions are analyzed through a spin wave analysis and mathematical arguments. At weak interactions, by analogy with the Kane-Mele model, the system is described through a Z2 topological invariant. In addition, we describe how the anisotropic spin-orbit coupling already produces an exotic spin texture at the edges. The physics at the Mott transition is described in terms of a U (1) slave rotor theory. Taking into account gauge fluctuations around the mean-field saddle point solution, we show how the spin texture now proliferates into the bulk above the Mott critical point. The latter emerges from the response of the spinons under the insertion of monopoles and this becomes more pronounced as the spin-orbit coupling becomes prevalent. We discuss implications of our predictions for thin films of the iridate compound Na2IrO3 and also graphene-like systems.

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Fluctuation-driven topological Hund insulators

Cited by 84 publications

References 59 publications

Topological Invariants for Spin-Orbit Coupled Superconductor Nanowires

Topological Invariants for Spin-Orbit Coupled Superconductor Nanowires

Nickel-titanium double perovskite: A three-dimensional spin-1 Heisenberg antiferromagnet

Anisotropic quantum spin Hall effect, spin-orbital textures, and the Mott transition

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