Topological type-II nodal line semimetal (NLS) was proposed quite recently and exhibits distinct properties compared with conventional type-I NLS. To date, no ambient-condition stable candidate material has been reported. Here we propose that a Kagome compound Mg3Bi2 can host state the protection of time reversal spatial inversion symmetries. Similar to NLSs, in is characterized by drumhead surface states, which not observed previous NLSs. The open minor gap, pair 3D Dirac points occurs when...

Identifying applicable anode materials is a significant task for Li- and Na-ion battery (LIB NIB) technologies. We propose the GaN monolayer (2D GaN) can be good candidate. The manifests stable Li/Na adsorption inherently low theoretical voltages. Most excitingly, both high storage capacity extremely fast diffusion simultaneously realized in monolayer. For Li, barrier 938 mA h g-1 80 meV , respectively. And values Na are 625 22 meV. Comparing with known 2D similar scale of ion barriers,...

Nodal line semimetals in two-dimensional (2-D) materials have attracted intense attention currently. From fundamental physics and spintronic applications points of view, high Curie temperature ferromagnetic (FM) ones with nodal lines robust against spin-orbit coupling (SOC) are significantly desirable. Here, we propose that FM K2N monolayer is such Weyl semimetal. We show dynamically stable, has a ground magnetic state the out-of-plane [001] magnetization. It shows two low-energy band...

Second‐order topological insulators (SOTIs) in 2D materials have attracted significant research interest. Recent theoretical predictions suggest that SOTIs can be achievable magnetic systems, especially within ferromagnetic (FM) materials. Yet, the quest for suitable antiferromagnetic (AFM) capable of hosting remains a challenge. Herein, utilizing first‐principles calculations and analysis, CrSBr is proposed, including monolayer bilayer forms, as promising candidate high‐order insulator. The...

The exploration of topological quantum phases and their transitions has become a focus intense research. In this paper, we introduce family two-dimensional (2D) metal-organic frameworks (MOFs) that host various emergent 2D fermions second-order insulators (SOTIs) while also exhibiting strain-tunable phase transitions. Using first-principles calculations, demonstrate these MOFs can exhibit either narrow-band-gap semiconductor or zero-band-gap semimetal state, with three key bands in the...

The topological flat band close to the Fermi level serves as a promising platform for realizing unique and intriguing phenomena. In theory, such can appear in certain geometrically frustrated lattices under stringent conditions, then generally be destroyed by hybridization with other bands application of external fields. Consequently, realistic materials that host are very rare. Via first-principles calculations, we investigate electronic structure monolayer MOF PTC-Fe, which kagome lattice...

In most Weyl semimetal (WSMs), the nodes with opposite chiralities usually have same type of band dispersions (either type-I or type-II), whereas realistic candidate materials hosting different types not been identified to date. Here we report for first time that, a ternary compound HfCuP, is an excellent WSM coexistence and type-II nodes. Our results show HfCuP totally contains six pairs in Brillouin zone, all locating at H-K path. These situate slightly below Fermi level, do coexist other...

Triply degenerate band crossing can generate novel triply nodal point (TDNP) fermions. For the TDNP character to best manifest in physical properties, it desires that TDNPs are near Fermi level, far away with each other reciprocal space, and not coexisting quasiparticles or extraneous bands. Here we predict centrosymmetic material Li2NaN is a realistic semimetal meets all these requirements. features only single pair of at under protection C6v symmetry. Interestingly, identified here show...

NaAlSi manifests both topological band structures and superconductivity, which is promising to realize a superconducting state.

Topological semimetals and metals have been extensively studied in nonmagnetic materials, while those magnetic materials are still quite rare. Here, based on first-principles calculations, we reveal that a family of hexagonal compounds $X{\mathrm{TiO}}_{2}$ ($X$ = Li, Na, K, Rb) with ferromagnetic ground states host excellent topological electronic structures. In their low-energy band structures, they show two Weyl nodal loops surfaces, where each loop surface is contributed by the electron...

The transition metal dichalcogenides, 2H-VX

In recent years, realizing new topological phase of matter has been a hot topic in the fields physics and materials science. Topological semimetals metals can conventionally be classified into two types: type-I type-II according to tilting degree fermion cone. Here, it is first time report metal with critical-type nodal line between line. The shows unique nontrivial band crossing which composed at dispersive leads fermionic state. We propose intermetallic CaPd an existing for state,...

Antiferromagnetic β-Fe₂PO₅ is a new topological semimetal with coexisting rich fermionic states, and the potential to be applied in antiferromagnetic spintronics.

The chain-type nodal loops in the reciprocal space can generate exotic chain fermions. Here, we report that Li2XY (X = Ca, Ba; Y Si, Ge) compounds are ideal inner semimetals. Their band structures composed of two connecting with either hybrid or type-I dispersion. signatures chain, such as nontrivial surface states, quite pronounced these compounds, since there is only a single without other extraneous bands near Fermi level. These existing materials and ambient-stable, which available to...

Exploring the relationship between magnetism and band topology has become a popular research topic in condensed matter physics. In this work, we investigate interplay two-dimensional (2D) metal-organic framework (MOF) ${\mathrm{Mn}}_{3}{({\mathrm{C}}_{6}{\mathrm{O}}_{6})}_{2}$. We discover that MOF ``soft'' ferromagnetic property, making it possible to control topological phases by adjusting magnetization direction. its ground state, Weyl points precisely located at Fermi level only one spin...

We propose for the first time concept and properties of topological electride materials.

CsCl-type materials have many outstanding characteristics, i.e. simple in structure, ease of synthesis and good stability at room temperature, thus are an excellent choice for designing functional materials. Using high-throughput first-principles calculations, a large number topological semimetals/metals (TMs) were designed from found crystallographic databases their crystal electronic structures been studied. The TMs this work show rich character, ranging triple nodal points, type-I lines...

We report the magnetization, electrical resistivity, specific heat measurements and band structure calculations of layered superconductor SnTaS$_2$. The experiments are performed on single crystals grown by chemical vapor transport method. resistivity magnetic susceptibility indicate that SnTaS$_2$ is a type-II with transition temperature $T_c = 3$ K. upper critical field ($H_{c2}$) shows large anisotropy for parallel to $ab$ plane ($H//ab$) $c$ axis ($H//c$), dependence $H_{c2}$ $H//ab$...

A type-II nodal line state, along with its unique optical, magnetic, and transport properties, was theoretically proposed experimentally evidenced quite recently. Here, based on first-principles calculations, we report that a pure Ti metal can serve as an excellent material for experimental detection. In the metal, situates in large momenta region linear energy range larger than 1.5 eV. Its surface band is dispersive thus promising to be detected wide range. The position of flexibly tuned by...

A YN₂ monolayer can realize multiple topological phases, determined based on the magnetization direction. In particular, in-plane QAHE be realized in a d⁰ ferromagnet.