Coexistence of topological Weyl and nodal-ring states in ferromagnetic and ferrimagnetic double perovskites

Zhao, Xinlei; Guo, Peng‐Jie; Ma, Fengjie; Lu, Zhong-Yi

doi:10.1103/physrevb.103.085138

Cited by 17 publications

(10 citation statements)

References 84 publications

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“…We also show that how the HSSs connect the projection of the nodal ring and the curvature of HSSs depend sensitively on the energy. Such unique surface-state connection also appear in several previous studies, yet lack of discussion [22][23][24][25][26]. Our results show that the connection pattern of the surface states is surface-dependent for systems with both Weyl and node-ring fermions, and it is universal for systems with/without considering SOC and T symmetry.…”

supporting

confidence: 78%

“…We notice that such unique surface-state connection behavior can be found in other materials with different symmetries, such as in the electronic band structure of FM HgCr 2 Se 4 (with SOC and without T ) [24], the electronic band structure of FM double perovskites (Ba 2 N aOsO 6 , Sr 2 SrOsO 6 , Ba 2 ZnReO 6 , Ba 2 M gReO 6 , and Ba 2 CdReO 6 , with SOC and without T ) [22,23], and the phonon band structure of oxide perovskites (BaT iO 3 , P bT iO 3 , without SOC and with T ) [26]. However, none of those works discuss on the connection of the unique surface states, and they mainly focus on the topology of the bulk bands.…”

Section: (F)mentioning

confidence: 76%

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Unique surface-state connection between Weyl and nodal ring fermions in ferromagnetic material Cs2MoCl6

Zhang,

Hara,

Murakami

2021

Preprint

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For topological materials with coexistence of Weyl nodes and nodal rings, the surface-state configuration and connection are unique yet have never been studied and discussed before. In this paper, we predict a ferromagnetic (FM) material, Cs2MoCl6, with coexistence of Weyl and nodering fermions in its spinful FM electronic band structure, which is unusual since FM materials are very rare in nature and node-ring band crossings will usually open a gap when spin-orbit coupling (SOC) is taken into consideration. We find that the surface states of Cs2MoCl6 show different properties along different directions, i.e, the surface states are in the drumhead shape showing the node-ring property on the (001) surface and in the helicoid shape showing the Weyl property on the (010) surface. Interestingly, both the drumhead surface states and the helicoid surface states will cross the projected points of the Weyl and nodal ring along different directions. In particular, helicoid surface states on the (010) surface will meet the nodal ring tangentially, with their shapes change abruptly as a function of the energy. We implement both first-principle calculation and an analytical model to understand the unique surface-state connection for systems with the coexistence of Weyl nodes and nodal rings (or nodal lines). This result is universal and irrespective of the presence/absence of and time-reversal symmetry (T ).

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supporting

confidence: 78%

Section: (F)mentioning

confidence: 76%

Unique surface-state connection between Weyl and nodal ring fermions in ferromagnetic material Cs2MoCl6

Zhang,

Hara,

Murakami

2021

Preprint

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“…Based on the first-principles calculations, the Ba 2 CdReO 6 double perovskite compound has been predicted as an intrinsic ferromagnetic topological semi-half-metal, while the ferrimagnetic double perovskite Ba 2 FeMoO 6 was found to be a topological half-metal . Coexistence of topological Weyl and nodal-ring states has been found . Chern Bands and Chern Insulators have been discussed for double perovskite heterostructures. , Following this, the topological properties of magnetic hybrid perovskites based on 4d and 5d TMs, as proposed in this study, should be investigated.…”

Section: Discussionmentioning

confidence: 89%

“…This is in contrast to e g -orbital based proposals which are prone to strong JT distortions that tend to favor trivial insulators. Based on the first-principles calculations, the Ba 2 CdReO 6 double perovskite compound has been predicted as an intrinsic ferromagnetic topological semi-half-metal, while the ferrimagnetic double perovskite Ba 2 FeMoO 6 was found to be a topological half-metal . Coexistence of topological Weyl and nodal-ring states has been found .…”

Section: Discussionmentioning

confidence: 95%

Rational Design of Magnetic Hybrid Transition Metal Double Perovskites in Polyatomic Anionic Systems

Sen

Saha‐Dasgupta

2022

Chem. Mater.

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Motivated by the exciting magnetic properties exhibited by inorganic transition metal based double perovskites A 2 BB′O 6 , we computationally explore designing of hybrid double perovskites with transition metal elements at the B sublattice. We focus our attention on compounds with the organic group methylammonium (MA + ) at the A site and polyatomic cyanide, (CN) − , as the molecular linker. This restricts our search to the monovalent/divalent cation at the B site and trivalent/divalent cations at the B′ site. Fixing Cu as the choice of cation at the B site, we scan the elemental space of the 3d, 4d, and 5d transition metal series. Our study reveals an interesting interplay of electronegativity, crystal field, and filling effect in structural, electronic, and magnetic properties of these yet-to-be synthesized compounds. Several of the proposed compounds are found to be strongly magnetic with antiferromagnetic coupling and moderately high Neeĺ temperature. Our computational study involving Ag in place of Cu provides rare examples of Ag(II) compounds. ■ INTRODUCTIONPerovskites, with the general formula ABX 3 , where A is an alkaline or rare-earth element, B is a metal cation, and X is oxygen or chalcogen, exhibiting a structural motif of corner shared BX 6 octahedra, have remained an evergreen field of research due to their fascinating properties. 1 In recent years, hybrid perovskites, 2 a family of compounds related to inorganic perovskites, where A is a small organic group such methylammonium (MA + ) or formamidinium (FA + ) instead of an alkaline or rare-earth element and X is an inorganic/organic anionic bridging ligand such as single-atom halide or polyatomic molecular linkers like cyanide, formate, azide, etc., have drawn significant attention due to their rich properties, which include photovoltaic, conducting, optical, electrical, and magnetic properties, together with easy and cheap synthesis conditions. 3−6 It has been also realized that while single, "B-metal" perovskites may provide limited advances, drawing a parallel from the inorganic world, double perovskites with the formula A 2 BB′X 6 can provide rich compositional diversity that in turn may result in promising new properties. With the choice of an A site cation from a similar pool of protonated amines as in single B site perovskites, B and B′ offer a wide range of choices, replacing the divalent metals in single B site perovskites, by a combination of monovalent and trivalent metal ions, such as

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“…Double-perovskites are a fascinating and rich family of materials exhibiting a variety of magnetic properties [15,25,[27][28][29][30][31][32][33][34]. They have the general chemical form A 2 BB O 6 where A belongs to the family of rare-earth elements or alkaline earth metals, B/B typically belong to the transition metals and O is oxygen.…”

Section: B Tight-binding Hamiltonianmentioning

confidence: 99%

Competing multipolar orders in a face-centered cubic lattice: Application to the osmium double perovskites

Churchill,

Kee

2021

Preprint

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In 5d 2 Mott insulators with strong spin-orbit coupling, the lowest pseudospin states form a non-Kramers doublet, which carries quadrupolar and octupolar moments. A family of double-perovskites where magnetic ions form a face-centered cubic (FCC) lattice, was suggested to unveil an octupolar order offering a rare example in d-orbital systems. The proposed order requires a ferromagnetic (FM) octupolar interaction, since the antiferromagnetic (AFM) Ising model is highly frustrated on the FCC lattice. A microscopic model was recently derived for various lattices: for an edge sharing octahedra geometry, AFM Ising octupolar and bond-dependent quadrupolar interactions were found when only dominant inter-and intra-orbital hopping integrals are taken into account. Here we investigate all possible intra-and inter-orbital exchange processes and report that interference of two intra-orbital exchanges generates a FM octupolar interaction. Applying the strong-coupling expansion results together with tight binding parameters obtained by density functional theory, we estimate the exchange interactions for the Osmium double-perovskites, Ba2BOsO6 (B = Mg, Ca). Using classical Monte-Carlo simulations, we find these double-perovskites exhibit type-I AFM quadrupolar order followed by an intriguing partial quadrupole order above the transition temperature, despite the FM octupolar interaction. However, the system is close to a phase boundary to the octupolar order and ways to generate the octupolar order are discussed.

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Coexistence of topological Weyl and nodal-ring states in ferromagnetic and ferrimagnetic double perovskites

Cited by 17 publications

References 84 publications

Unique surface-state connection between Weyl and nodal ring fermions in ferromagnetic material Cs2MoCl6

Unique surface-state connection between Weyl and nodal ring fermions in ferromagnetic material Cs2MoCl6

Rational Design of Magnetic Hybrid Transition Metal Double Perovskites in Polyatomic Anionic Systems

Competing multipolar orders in a face-centered cubic lattice: Application to the osmium double perovskites

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