Dirac Half-Metal in a Triangular Ferrimagnet

Ishizuka, Hiroaki; Motome, Yukitoshi

doi:10.1103/physrevlett.109.237207

Cited by 86 publications

(49 citation statements)

References 19 publications

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“…The Dirac electrons are almost fully spin polarized by the large Hund's-rule coupling. A similar Dirac half-semimetal was also found at 1/3 filling in a different ferrimagnetic phase in the absence of the AFM SE interaction [40]. In our KN state, however, excess electrons over half filling are effectively regarded as spinless fermions on the kagome lattice at 1/3 filling.…”

Section: Introductionsupporting

confidence: 78%

Spontaneous formation of kagome network and Dirac half-semimetal on a triangular lattice

Akagi

Motome

2015

Phys. Rev. B

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In spin-charge coupled systems, geometrical frustration of underlying lattice structures can give rise to nontrivial magnetic orders and electronic states. Here we explore such a possibility in the Kondo lattice model with classical localized spins on a triangular lattice by using a variational calculation and simulated annealing. We find that the system exhibits a four-sublattice collinear ferrimagnetic phase at 5/8 filling for a large Hund's-rule coupling. In this state, the system spontaneously differentiates into the up-spin kagome network and the isolated down-spin sites, which we call the kagome network formation. In the kagome network state, the system becomes Dirac half-semimetallic: The electronic structure shows a massless Dirac node at the Fermi level, and the Dirac electrons are almost fully spin polarized due to the large Hund's-rule coupling. We also study the effect of off-site Coulomb repulsion in the kagome network phase where the system is effectively regarded as a 1/3-filling spinless fermion system on the kagome lattice. We find that, at the level of the mean-field approximation, a √ 3 × √ 3-type charge order occurs in the kagome network state, implying the possibility of fractional charge excitations in this triangular lattice system. Moreover, we demonstrate that the kagome network formation with fully-polarized Dirac electrons are controllable by an external magnetic field.

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Section: Introductionsupporting

confidence: 78%

Spontaneous formation of kagome network and Dirac half-semimetal on a triangular lattice

Akagi

Motome

2015

Phys. Rev. B

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“…They can also break the protection of time-reversal symmetry (TRS) but maintain the linear relation of energy-momentum dispersion at the Fermi level, resulting in outstanding transport properties. Such a type of material was theoretically proposed in a triangular ferrimagnet in recent years [24], but this novel class of structures is very rare and has only been predicted in a limited number of configurations such as CrO 2 =TiO 2 heterostructure [26], Mn-intercalated graphene [13], and the NiCl 3 monolayer [27]. Yet no Dirac half-metal has been experimentally synthesized [28].…”

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confidence: 99%

“…However, to overcome the "grand challenge," the performances of half-metal and SGS are still limited as it just behaves like a metal-semiconductor in one spin orientation, but lacks linear Dirac dispersion, which can hardly reach the goal of ultrahigh speed spin transport. Therefore, it is of great interest to explore new platforms with spin-polarized linear energy dispersion (Dirac half-metal) and massless Dirac fermions, which will lead towards realistic applications in high effieciency spintronics and quantum information technologies [19,24,25]. Dirac materials with spin-polarized band structures can effectively utilize spin degrees of freedom of electrons.…”

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confidence: 99%

First-Principles Prediction of Spin-Polarized Multiple Dirac Rings in Manganese Fluoride

Jiao

Zhang

et al. 2017

Phys. Rev. Lett.

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Spin-polarized materials with Dirac features have sparked great scientific interest due to their potential applications in spintronics. But such a type of structure is very rare and none has been fabricated. Here, we investigate the already experimentally synthesized manganese fluoride (MnF 3 ) as a novel spin-polarized Dirac material by using first-principles calculations. MnF 3 exhibits multiple Dirac cones in one spin orientation, while it behaves like a large gap semiconductor in the other spin channel. The estimated Fermi velocity for each cone is of the same order of magnitude as that in graphene. The 3D band structure further reveals that MnF 3 possesses rings of Dirac nodes in the Brillouin zone. Such a spin-polarized multiple Dirac ring feature is reported for the first time in an experimentally realized material. Moreover, similar band dispersions can be also found in other transition metal fluorides (e.g., CoF 3 , CrF 3 , and FeF 3 ). Our results highlight a new interesting single-spin Dirac material with promising applications in spintronics and information technologies. DOI: 10.1103/PhysRevLett.119.016403 Ever since the spin and charge of one electron have been considered separately, it has been found that the spin current displays superior properties to the classical charge current in the field of information transmission such as high speed, low power consumption, and negligible energy dissipation [1]. Thus, the corresponding spin current has drawn great attention over the past few decades and the spin electronics are rapidly expanding [2][3][4][5][6][7][8][9][10][11]. Up to now, a number of spintronics materials have been proposed including magnetic metals, half-metallic ferromagnets, topological insulators, magnetic semiconductors, diluted magnetic semiconductors, etc. [12][13][14][15][16]. But to exploit the full potential of spintronics in information transfer and storage, some basic issues still remain, such as long distance spin transport, and the generation and injection of spin polarized currents [4,17,18]. In addition to them, the grand challenges for new generation spintronics are how to make electrons transport with ultrahigh speed and consume ultralow energy, which requires realizing massless electrons by discovering the potential Dirac band dispersion, and achieve dissipationless spin transport via generating large spin polarization around the Fermi level [19].It is necessary to emphasize that the well-studied materials for spintronics such as half-metals, can meet the "basic" demand of spintronics applications [20,21]. In addition, Wang [22] proposed a new class of materials named spin gapless semiconductors (SGS) that can generate 100% spin polarized current and is promising in spintronics. The SGS was then validated by Ouardi et al. in experiment [23]. However, to overcome the "grand challenge," the performances of half-metal and SGS are still limited as it just behaves like a metal-semiconductor in one spin orientation, but lacks linear Dirac dispersion, which can hardly reach t...

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“…In particular, an interesting ferrimagnetic phase supporting an emergent Dirac point is observed in the triangular KLM with Ising anisotropy. 64 …”

Section: Metallic Spin Icesmentioning

confidence: 99%

Novel Magnetic Orders and Ice Phases in Frustrated Kondo-Lattice Models

Chern

2015

SPIN

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We review recent theoretical progress in our understanding of electron-driven novel magnetic phases on frustrated lattices. Our speci¯c focus is on Kondo-lattice or double-exchange models assuming¯nite magnetic moments localized at the lattice sites. A salient feature of systems with SU(2) symmetric local moments is the emergence of noncoplanar magnetic ordering driven by the conduction electrons. The complex spin textures then endow the electrons a nontrivial Berry phase, often giving rise to a topologically nontrivial electronic state. The second part of the review is devoted to the discussion of metallic spin ice systems, which are essentially frustrated Ising magnets with local spin ordering governed by the so-called ice rules. These rules are similar to those that describe proton con¯gurations in solid water ice, hence the name \spin ice". The nontrivial spin correlations in the ice phase give rise to unusual electron transport properties in metallic spin-ice systems.

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Dirac Half-Metal in a Triangular Ferrimagnet

Cited by 86 publications

References 19 publications

Spontaneous formation of kagome network and Dirac half-semimetal on a triangular lattice

Spontaneous formation of kagome network and Dirac half-semimetal on a triangular lattice

First-Principles Prediction of Spin-Polarized Multiple Dirac Rings in Manganese Fluoride

Novel Magnetic Orders and Ice Phases in Frustrated Kondo-Lattice Models

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