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

Abstract

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...

Recent advances in Dirac spin-gapless semiconductors

“…Interestingly, already prepared MnF 3 had been identified and investigated by chemists for a long time, [83][84][85][86] but there had been no theoretical studies of its electronic band structure. In 2017, Jiao et al 87 demonstrated the DSGS features of MnF 3 by means of first-principles calculations and predicted a series of novel properties. This work focused on a phase of MnF 3 (also called b-MnF 4 ) that had been synthesized in experiments for many years, i.e., its hexagonal bulk structure (space group, R-3c, No.167), corresponding illustration is shown in Fig.…”

“…We think the following experimental work, which is about achieving true DSGS state by coverage modulation in Mn-intercalated epitaxial graphene on SiC (0001), is still meaningful. Additionally, to achieve further advances in the search for DSGSs that can be synthesized experimentally, we suggest that researchers consider the synthetic potential of compounds such as the 2D graphitic carbon nitrides, 98 TM halides, 80,81,87,90 and simple oxide heterostructures, 69 which are usually built into either honeycomb lattices or cubic types according to computations. The structural designs of these materials are all based on further explorations in well-known traditional compounds (such as tri-s-tri-azine, TMF 3 , and the CrO 2 /TiO 2 heterostructures), which have been widely synthesized and used by chemists for a long time.…”

Intrinsic Half‐Metallicity in 2D Ternary Chalcogenides with High Critical Temperature and Controllable Magnetization Direction

“…Among the intrinsically magnetic 2D materials reported, it is observed that transition‐metal‐centered octahedral unit is one of the key building blocks . The different electronic occupation configurations of transition metal centers and different interaction between transition metals and coordination atoms lead to various exchange processes and magnetic anisotropic strength, and thus various interesting magnetic behaviors observed recently .…”

Predicting the ground-state structure of sodium boride

“…The particular nodal rings should be protected by the combination of inversion and time-reversal symmetry, 27 which are expected to have more intensive nonlinear electromagnetic response than Dirac semimetals with a single cone, and thus possess a higher efficiency of carrier trans- port at the Fermi level via multiple Dirac channels. 28 In Imm2-Na 2 B 29 , due to very close structure similarity, the nodal rings could be preserved. However, because of minor concentration of B vacancies, the Fermi level is shifted down by 0.62 eV, to the valence band ( Fig.…”