Electronic Band Dispersion Research Articles

First-principles screening of optoelectronics and thermoelectric response of XAcTe2 (X=K, Rb) full Heusler alloys: mBJ+SOC effect

Structural geometry, Electronic, optical, and thermoelectric attributes of XAcTe2 (X=K,Rb) full Heuser alloys were investigated theoretically via density functional theory (DFT). Structural optimization yielded optimized lattice parameters along with obtained negative formation energies (Ef) revealed the thermodynamically stable cubic geometries of alloys under investigation. For both alloys, the computed electronic band dispersions exhibit semiconductor behavior with a direct band gap. The band gap value of KAcTe2 is 1.59 eV, and 1.66 eV for RbAcTe2. The analysis of optical response shows maximum absorption α (ω) in the ultraviolet (UV) region, validating their quality for photovoltaic devices. The investigation of thermoelectric characteristics showed that both alloys display higher electrical conductivities and lower thermal conductivities.

Evolution of structural and electronic properties standardized description in rhenium disulfide at the bulk-monolayer transition

The structural and electronic properties of ReS2 different forms — three-dimensional bulk and two-dimensional monolayer — were studied within density functional theory and pseudopotentials. A method for standardizing the description of bulk unit cells and "artificial" slab unit cells for DFT research has been proposed. The preference of this method for studying zone dispersion has been shown. The influence of the vacuum layer thickness on specified special high-symmetry points is discussed. Electron band dispersion in both classical 3D Brillouin zones and transition to 2D Brillouin zones in the proposed two-dimensional approach using the Niggli form of the unit cell was compared. The proposed two-dimensional approach is preferable for low-symmetry layered crystals such as ReS2. It was established that the bulk ReS2 is a direct gap semiconductor (band gap of 1.20 eV), with the direct transition lying in the X point of the first Brillouin zone, and it is in good agreement with published experimental data. The reduction in material dimension from bulk to monolayer was conducted with an increasing band gap up to 1.45 eV, with a moving direct transition towards the Brillouin zone center. The monolayer of ReS2 is a direct-gap semiconductor in a wide range of temperatures, excluding only a narrow range at low temperatures, where it comes as a quasi-direct gap semiconductor. The transition, situated directly in the Γ-point, lies 3.3 meV below the first direct transition located near this point. The electronic density of states of ReS2 in the bulk and monolayer cases of ReS2 were analyzed. The molecular orbitals were built for both types of ReS2 structures as well as the electron difference density maps. For all types of ReS2 structures, an analysis of populations according to Mulliken and Voronoi was carried out. All calculated data is discussed in the context of weak quantum confinement in the 2D case.

Weak electronic correlations observed in magnetic Weyl Semimetal Mn3Ge

Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT) calculations, we systematically studied the electronic band structure of Mn3Ge in the vicinity of the Fermi level. We observe several bands crossing the Fermi level, confirming the metallic nature of the studied system. We further observe several flat bands along various high symmetry directions, consistent with the DFT calculations. The calculated partial density of states suggests a dominant Mn 3d orbital contribution to the total valence band DOS. With the help of orbital-resolved band structure calculations, we qualitatively identify the orbital information of the experimentally obtained band dispersions. Out-of-plane electronic band dispersions are explored by measuring the ARPES data at various photon energies. Importantly, our study suggests relatively weaker electronic correlations in Mn3Ge compared to Mn3Sn.

Growth of Bi2Te3 topological insulator ultra-thin layers via molecular beam epitaxy on GaAs (100)

Ultra-thin layers (<8 nm) of a Bi2Te3 topological insulator have been grown on GaAs (100) substrates using molecular beam epitaxy. The growth was performed from a single Bi2Te3 effusion cell and one source of extra tellurium. Optical and structural characterizations were carried out through Raman spectroscopy, x-ray diffraction, atomic force microscopy, and scanning electron microscopy. The topological insulator properties were also investigated by angle-resolved photoelectron spectroscopy. A layer of 5 nm showed Dirac cone-like linear electronic band dispersion, indicating the signature of a topological insulator with the Dirac point having large binding energy relative to the Fermi level as expected for ultra-thin films. Topological insulator properties were also investigated at the initial growth stage where deposition follows an islandlike growth mode. Our results can contribute to the development of practical chalcogenide-based thin-film spintronics devices.

Thiophene Backbone Enables Two-Dimensional Poly(arylene vinylene)s with High Charge Carrier Mobility.

Linear conjugated polymers have attracted significant attention in organic electronics in recent decades. However, despite intrachain π-delocalization, interchain hopping represents their transport bottleneck. In contrast, two-dimensional (2D) conjugated polymers, as represented by 2D π-conjugated covalent organic frameworks (2D c-COFs), can provide multiple conjugated strands to enhance the delocalization of charge carriers in space. Herein, we demonstrate the first example of thiophene-based 2D poly(arylene vinylene)s (PAVs, 2DPAV-BDT-BT and 2DPAV-BDT-BP, BDT= benzodithiophene, BT=bithiophene, BP=biphenyl) via Knoevenagel polycondensation. Compared with 2DPAV-BDT-BP, the fully thiophene-based 2DPAV-BDT-BT exhibits enhanced planarity and π-delocalization with a small band gap (1.62 eV) and large electronic band dispersion, as revealed by the optical absorption and density functional theory calculations. Remarkably, temperature-dependent terahertz spectroscopy discloses a unique band-like transport and outstanding room-temperature charge mobility for 2DPAV-BDT-BT (65 cm2V-1s-1), which far exceeds that of the linear PAVs, 2DPAV-BDT-BP, and the reported 2D c-COFs in the powder form. This work highlights the great potential of thiophene-based 2D PAVs as candidates for high-performance opto-electronics.

Thiophenbasierte Polymergerüste ermöglichen zweidimensionale Poly(arylenvinylen)e mit hoher Ladungsträgermobilität

AbstractLineare konjugierte Polymere haben in den letzten Jahrzehnten große Aufmerksamkeit in der organischen Elektronik erhalten. Trotz der π‐Delokalisierung innerhalb der Polymerkette stellen Interketten‐Ladungsträgersprünge ihr hauptsächliches Transportproblem dar. Im Gegensatz dazu können zweidimensionale (2D) konjugierte Polymere, wie z. B. 2D π‐konjugierte Covalent Organic Frameworks (2D c‐COFs), mehrere konjugierte Stränge für eine verbesserte Delokalisierung von Ladungsträgern im Raum bereitstellen. Hierin zeigen wir das erste Beispiel von thiophenbasierten 2D‐Poly(arylenvinylen)en (PAVs, 2DPAV‐BDT‐BT und 2DPAV‐BDT‐BP, BDT=Benzodithiophen, BT=Bithiophen, BP=Biphenyl) synthetisiert über Knoevenagel‐Polykondensation. Im Vergleich zu 2DPAV‐BDT‐BP weist das vollständig thiophenbasierte 2DPAV‐BDT‐BT eine erhöhte Planarität und π‐Delokalisierung mit einer niedrigen elektronischen Bandlücke (1.62 eV) und einer hohen elektronischen Banddispersion auf, wie die optische Absorption und Dichtefunktionaltheorie Berechnungen zeigen. Bemerkenswerterweise offenbart die temperaturabhängige Terahertz‐Spektroskopie‐Messung einen einzigartigen bandartigen Transport und eine herausragende Raumtemperatur‐Ladungsbeweglichkeit für 2DPAV‐BDT‐BT (65 cm2 V−1 s−1), die die der linearen PAVs, 2DPAV‐BDT‐BP und der publizierten 2D c‐COFs in Pulverform weit übertrifft. Diese Arbeit unterstreicht das große Potenzial von thiophenbasierten 2D‐PAVs als Kandidaten für Hochleistungs‐Optoelektronik.

Study on the thermoelectric characteristics of the ternary alkali metal compound XMgSb (X = K, Rb, Cs)

We conducted a comprehensive analysis of the mechanical, transport, and thermoelectric (TE) characteristics of XMgSb (X = K, Rb, Cs) alkali metal compounds using first-principles calculations, self-consistent phonon theory, pressive sensing lattice dynamics, and the Boltzmann transport equation. Our results show that the very low lattice thermal conductivity of these materials is mainly attributed to the strong anharmonicity of the alkali metal atoms, and the lattice thermal conductivity is negatively correlated with the mass of X atoms. Furthermore, we consider five scattering mechanisms to accurately calculate transport properties and electron relaxation times. Notably, we observed that the large electronic dispersion band near the valence band maximum leads to the high conductivity of these three compounds, with a flat electronic energy band at the Γ-Z point, which generally implies a larger Seebeck coefficient. The coexistence of good electronic band dispersion and flat electronic bands leads to high conductivity and large Seebeck coefficient, resulting in high TE power. Low lattice thermal conductivity and high TE power factor jointly determine the development potential of alkali metal compound XMgSb (X = K, Rb, Cs) in the field of TE.

Evolution of electrical transport properties in FeTe2-CoTe2 solid solution system for optimum thermoelectric performance

Transition metal chalcogenides have received significant attention as electronic materials owing to their tunable electronic transport properties and unique crystal structures. In this work, the electrical, thermal, and thermoelectrical transport properties of FeTe2-CoTe2 solid solution system were investigated by synthesizing a series of (Fe1–xCox)Te2 polycrystalline alloys with x = 0, 0.25, 0.5, 0.75, and 1. FeTe2 and CoTe2 exhibited identical orthorhombic structures and formed a complete solid solution. (Fe1–xCox)Te2 system exhibits wide range of electronic transport characteristics; CoTe2 exhibits metallic conduction with high electrical conductivity of ∼8000 S/cm with electron carriers, whereas FeTe2 exhibits semiconducting conduction with relatively low electrical conductivity of ∼300 S/cm with hole carriers at room temperature. The optimum carrier transport for high power factor of 1.53 mW/cmK2 at 600 K is observed for (Fe0.5Co0.5)Te2 composition. The electronic band dispersions of FeTe2, (Fe0.5Co0.5)Te2, and CoTe2 were calculated by using the density functional theory and it was found that a distinct flat band is present near the Fermi level for Fe0.5Co0.5Te2, supporting the high power factor of Fe0.5Co0.5Te2. As the lattice thermal conductivity is reduced for the solid-solution samples with additional point defect scattering, the thermoelectric figure of merit (zT) increased significantly to 0.18 for Fe0.5Co0.5Te2 compared to 0.001 for FeTe2 or 0.08 for CoTe2 at 600 K.

Electronic, Thermal, and Thermoelectric Transport Properties of ReSe2 and Re2Te5

Re-based chalcogenides have been studied in various fields such as strain engineering, photodetection, spintronics, and electromechanics, as well as in piezoelectric and photonic devices. In this study, the electrical, thermal, and thermoelectric transport properties of two representative Re-based chalcogenides, ReSe2 and Re2Te5, are investigated systematically. Furthermore, their electronic band dispersions are calculated using density functional theory and compared with the phenomenological data. The maximum power factor values for the ReSe2 and Re2Te5 were measured 0.0066 and 0.11 mW/mK2 at 880 K, respectively. Thermal conductivity of layered ReSe2 at room temperature was between 1.93 and 8.73 W/mK according to the measuring direction. For Re2Te5 with a complex orthorhombic crystal structure, the thermal conductivity was quite low in the range between 0.62 and 1.23 W/mK at room temperature. As a result, the maximum z T values of ReSe2 were quite low as 0.0016 at 880 K due to very low power factor and high thermal conductivity. Meanwhile, the relatively high z T of 0.145 in Re2Te5 is obtained at 880 K, which is originated from the acceptable power factor value and the low thermal conductivity.

Identification of a Magnetic Phase via a Raman Spectrum in Single-Layer MnSe: An ab Initio Study

Motivated by the recent experimental realization of single-layer two-dimensional MnSe [ACS Nano2021, 15, 13794–13802], structural, magnetic, elastic, vibrational, and electronic properties of single-layer MnSe are investigated by using density functional theory-based calculations. Among four different magnetic phases, namely, ferromagnetic (FM) and Nẽel-, zigzag-, and stripy-antiferromagnetic (AFM) phases, the Nẽel-AFM structure is found to be the energetically most favorable phase. Structural optimizations show the formation of in-plane anisotropy within the structures of zigzag- and stripy-AFM phases in single-layer MnSe. For the dynamically stable four magnetic phases, predicted Raman spectra reveal that each phase exhibits distinctive vibrational features and can be distinguished from each other. In addition, the elastic constants indicate the mechanical stability of each magnetic phase in single-layer MnSe and reveal the soft nature of each phase. Moreover, electronic band dispersion calculations show the indirect band gap semiconducting nature with varying electronic band gap energies for all magnetic phases. Furthermore, the atomic orbital-based density of states reveals the existence of out-of-plane orbitals dominating the top valence states in zigzag- and stripy-AFM phases, giving rise to the localized states. The stability of different magnetic phases and their distinct vibrational and electronic properties make single-layer MnSe a promising candidate for nanoelectronic and spintronic applications.

Phase formation behavior and electronic transport properties of HfSe2-HfTe2 solid solution system

Transition metal dichalcogenides have gained renewed attention as promising thermoelectric materials primarily because of their unique structures and superior electronic properties. In this study, we investigate the electrical transport properties of a series of Hf(Se,Te)2 samples (Hf(SexTe1-x)2, x = 0, 0.025, 0.25, 0.375, 0.5, and 1). All the samples form a single phase of a complete solid solution, displaying a wide variety of electrical properties based on the evolution of the composition. HfTe2 exhibits metallic conduction with very high electrical conductivity of ~1600 S/cm, whereas HfSe2 exhibits semiconducting conduction with very low electrical conductivity of 0.33 S/cm at room temperature. In contrast, the Seebeck coefficient of the HfTe2 sample is as low as 17 μV/K, whereas that of HfSe2 approaches 730 μV/K. Therefore, the power factor for HfTe2 represents a much higher value of 0.24 mW/mK2 when compared with 0.01 mW/mK2 for HfSe2 at 600 K. The superior electrical transport properties of HfTe2 are primarily caused by its high carrier concentration of 1021 cm−3 and high density-of-state effective mass of 0.91m0. A comparison of the electronic band dispersion between HfSe2 and HfTe2 calculated using the density functional theory indicates that the dispersions of the conduction and valence bands seem to remain unchanged: HfSe2 exhibits a finite band gap, whereas HfTe2 exhibits no or a very small band gap.

Screening of the Coulomb interaction in C3N: Reduced dimensionality and electronic structure effects

Coulomb interactions in two-dimensional semimetals like graphene are not screened in the usual way, and sizable long-range interaction has been found. With the aim of achieving new materials with nonconventional screening, as well as, in order to investigate various effects such as reduced dimensionality and electronic band dispersion, we calculate the strength of the effective Coulomb interaction $U$ between ${p}_{z}$ electrons in recently developed hexagonal ${\mathrm{C}}_{3}\mathrm{N}$ materials from the first principles using the constrained random-phase approximation. We find that the calculated parameters in the monolayer of the ${\mathrm{C}}_{3}\mathrm{N}$ are larger than the ones in graphene and remain sizable even in metallic bilayers. Nonlocal Coulomb interactions $U(r)$ in nonmetallic ${\mathrm{C}}_{3}\mathrm{N}$ nanoribbons are almost 1 eV smaller than the ones for ${\mathrm{C}}_{3}\mathrm{N}$ monolayer. Our results show that similar to graphene, screening in hexagonal ${\mathrm{C}}_{3}\mathrm{N}$ is also nonconventional. This controversial screening of Coulomb interaction stems from the electronic structure and massless Dirac dispersion below Fermi energy, which has to be preserved for symmetry reasons in hexagonal ${\mathrm{C}}_{3}\mathrm{N}$ layers.

Evolution of geometric and electronic structures of oxygen-induced superstructures on Mo(110) surface: A LEED, ARPES, and DFT study

We have studied the evolution of atomic structure and electronic band dispersion of oxygen-induced superstructures on the Mo(110) surface by using low-energy electron diffraction, angle-resolved photoemission spectroscopy, and density functional theory. Our experiments show that adsorption of oxygen at an elevated temperature (473 K) gets rid of the mixed-phase coexisting region observed at room temperature and exhibits three distinct superstructures: $p(2\ifmmode\times\else\texttimes\fi{}2$), $p(2\ifmmode\times\else\texttimes\fi{}1$), and $p(2\ifmmode\times\else\texttimes\fi{}6$) phases. Oxygenation of the Mo(110) surface leads to a confinement-induced gaplike opening at the zone center that can be tuned by the overlayer oxygen coverage. The ``hole'' pockets on the Fermi surface of the clean Mo(110) surface are found to persist upon oxygen adsorption with slightly changed volumes, while the ``electron'' pocket does not show any significant shift in momentum with no Fermi surface nesting behavior until saturation oxygen coverages. Apart from the significant modifications to the electronic states of the clean Mo(110) surface, we also observe the formation of new oxygen-induced bands. The evolution of the surface states near ${E}_{F}$ can be attributed to a change in the surface potential, while the evolution of oxygen-induced bands results from the hybridization between O-$2p\phantom{\rule{4pt}{0ex}}({m}_{j}=1/2$) and Mo-$4d$ (${m}_{j}=1/2$) orbitals at the interface. The interlayer separation, bond length, and lateral repulsive interactions between the adatoms are found to play a crucial role in the selective chemisorption of the Mo(110) surface.

Odd-even layer-number effect of valence-band spin splitting in WTe2

When a crystal becomes thin to the atomic level, peculiar phenomena discretely depending on its layer numbers ($n$) start to appear. Here, we investigate the electronic band dispersions of multilayer ${\mathrm{WTe}}_{2}$ (2--5 layers), by performing laser-based microfocused angle-resolved photoelectron spectroscopy on exfoliated flakes sorted by $n$. We observe that the holelike valence bands start to cross the Fermi level when the number of layers is increased from 2- to 3 layers, which should be related to the insulator-semimetal transition, as well as the 30--70-meV spin splitting of valence bands manifesting in even $n$ as a signature of stronger structural asymmetry. Our result fully demonstrates the possibility of the large energy-scale band and spin manipulation through the finite-$n$ stacking procedure.

Enhancement of superconductivity on the verge of a structural instability in isovalently doped β-ThRh1−xIrxGe

β-ThRhGe, the high-temperature polymorph of ThRhGe, is isostructural to the well-known ferromagnetic superconductor URhGe. However, contrary to URhGe, β-ThRhGe is nonmagnetic and undergoes an incomplete structural phase transition at 244 K, followed by a superconducting transition below 3.36 K. Here we show that the isovalent substitution of Ir for Rh leads to a strong enhancement of superconductivity by suppressing the structural transition. At x = 0.5, where the structural transition disappears, Tc reaches a maximum of 6.88 K. The enhancement of superconductivity is linked to the proximity to a structural quantum critical point at this Ir concentration, as suggested by the analysis of thermodynamic as well as resistivity data. First principles calculations indicate that the Ir doping has little effect on the electronic band dispersion near the Fermi level. β-ThRh1−xIrxGe thus provides an excellent platform to study the interplay between superconductivity and structural quantum criticality in actinide-containing compounds.

Theoretical exploration of the optoelectronic properties of InAsNBi/InAs heterostructures for infrared applications: A multi-band k·p approach

We have investigated numerous electronic and optical aspects of the InAsNBi material, considering a multi-band k·p Hamiltonian. We have scrutinised electronic band dispersion, changes in spin–orbit splitting energy (so), charge carrier effective mass, band offset, and optical gain variations of InAsNBi and Quantum Well (QW) structures lattice-matched to InAs. The band gap of InAs0.9209N0.0291Bi0.05 is observed to be 131 meV under lattice-matched conditions, and the operating wavelength equivalent to this bandgap is 9.46 μm, which corresponds to the atmospheric Long Wavelength Infrared (LWIR) communication window of 8–12 μm. In order to tune the bandgap of a quantum confined heterostructure over a wide range, strain analysis plays a pivotal role. While compressive strain of 0.7% offers a band gap of 96 meV, tensile strain of 1.16% generates a band gap to 178 meV, which is almost equivalent to the room temperature bandgap of InSb. Under the influence of strain, spin-orbit splitting energy (Δso) spans the range from 0.31 eV to 0.45 eV. In addition to this, the inclusion of N and Bi into InAs reduces the effective mass of electrons to 0.01343 m0, which is ∼0.5 times of InAs. We have also computed the band structure of the InAsNBi/InAs QW heterostructure and found that under the influence of tensile strain with N = 2.5% and Bi = 1%, there is a changeover from Type-I to Type-II heterostructure. Indeed, InAsNBi can be a potential material for realizing various optoelectronic applications such as atmospheric LWIR communication, intermediate band solar cells, and night vision cameras.

First-principles insights into the mechanical, optoelectronic, thermophysical, and lattice dynamical properties of binary topological semimetal BaGa2

In the present study we have investigated the structural properties, electronic band dispersion, elastic constants, acoustic behavior, phonon spectrum, optical properties, and a number of thermophysical parameters of binary topological semimetal BaGa2 in details via first-principles calculations using the density functional theory (DFT) based formalisms. The electronic band structure and density of states calculations with spin–orbit coupling reveal semimetallic nature with clear topological signatures. The minimum thermal conductivities and anisotropies of the compound are calculated. The elastic constants and phonon dispersion calculations show that the compound under study is both mechanically and dynamically stable. Comprehensive study of elastic parameters shows that BaGa2 possesses fairly isotropic mechanical properties, reasonably good machinability, low Debye temperature and melting point. The chemical bonding in BaGa2 is interpreted via the electronic energy density of states, electron density distribution, elastic properties and Mulliken bond population analysis. The compound possesses both ionic and covalent bondings. The reflectivity spectra show strong anisotropy with respect to polarization of the incident electric field in the visible to mid-ultraviolet regions. High reflectivity over wide spectral range makes BaGa2 suitable as a reflecting material. BaGa2 is also an efficient absorber of ultraviolet radiation. Furthermore, the refractive index is quite high in the infrared to visible range. All the energy dependent optical parameters show metallic features and are in complete accord with the underlying bulk electronic density of states calculations. Most of the results presented in this study are novel and should serve as useful reference for future study.

Doping dependence of the electron-phonon coupling in two families of bilayer superconducting cuprates

While electron-phonon coupling (EPC) is crucial for Cooper pairing in conventional superconductors, its role in high-$T_c$ superconducting cuprates is debated. Using resonant inelastic x-ray scattering at the oxygen $K$-edge, we studied the EPC in Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212) and Nd$_{1+x}$Ba$_{2-x}$Cu$_3$O$_{7-\delta}$ (NBCO) at different doping levels ranging from heavily underdoped ($p =0.07$) to overdoped ($p=0.21$). We analyze the data with a localized Lang-Firsov model that allows for the coherent excitations of two phonon modes. While electronic band dispersion effects are non-negligible, we are able to perform a study of the relative values of EPC matrix elements in these cuprate families. In the case of NBCO, the choice of the excitation energy allows us to disentangle modes related to the CuO$_3$ chains and the CuO$_2$ planes. Combining the results from the two families, we find the EPC strength decreases with doping at $\mathbf{q_\parallel}=(-0.25, 0)$ r.l.u., but has a non-monotonic trend as a function of doping at smaller momenta. This behavior is attributed to the screening effect of charge carriers. We also find that the phonon intensity is enhanced in the vicinity of the charge-density-wave (CDW) excitations while the extracted EPC strength appears to be less sensitive to their proximity. By performing a comparative study of two cuprate families, we are able to identify general trends in the EPC for the cuprates and provide experimental input to theories invoking a synergistic role for this interaction in $d$-wave pairing.

Half-metallicity induced by out-of-plane electric field on phosphorene nanoribbons

Exploring the half-metallic nanostructures with large band gap and high carrier mobility is a crucial solution for developing high-performance spintronic devices. The electric and magnetic properties of monolayer zigzag black-phosphorene nanoribbons (ZBPNRs) with various widths are analyzed by means of the first-principles calculations. Our results show that the magnetic ground state is dependent on the width of the nanoribbons. The ground state of narrow nanoribbons smaller than 8ZBPNRs prefers ferromagnetic order in the same edge but antiferromagnetic order between two opposite edges. In addition, we also calculate the electronic band dispersion, density of states and charge density difference of 8ZBPNRs under the action of out-of-plane electric field. More interesting, the addition of out-of-plane field can modulate antiferromagnetic semiconductor to the half metal by splitting the antiferromagnetic degeneracy. Our results propose a new approach to realize half-metal in phosphorene, which overcomes the drawbacks of graphene/silicene with negligible band gap as well as the transitional metal sulfide (TMS) with low carrier mobility.

Remarkable Topological Features of Electronic Band Dispersion of IrGa and RhGa Compounds from First Principles

Exotic behavior of linearly dispersed electronic bands near the Fermi level implies advanced physical properties in a material. In this paper, we present an ab initio study of the electronic properties of IrGa and RhGa, with and without spin-orbit interaction, using first-principles calculations. Linearly dispersed band crossings, reminiscent of topological semimetallic band structures, were identified near the Fermi energy. These include type-I and type-II Dirac points and nodal lines. By applying compressive and tensile stress to the lattice along x, y, and z, the response to the band structure near the Fermi level has been studied.