Hg2CuTi-type Structure Research Articles

Evolution of structure, magnetism, and electronic/thermal-transports of Ti(Cr)-substituted Fe2CrV all-d-metal Heusler ferromagnets

All-d-metal full-Heusler alloys possess superior mechanical properties and high spin polarization, which would play an important role in spintronic applications. Despite this, their electrical and thermal transport properties have not been comprehensively investigated till now. In this work, we present an analysis on the evolution of structural, magnetic and transport properties of Cr- and Ti-substituted Fe2CrV all-d-metal Heusler alloys by combining theoretical calculations and experiments. Both series of alloys crystallize in Hg2CuTi-type structure. With increasing Ti doping, the calculated total magnetic moments of Fe50Cr25V25-xTix decrease linearly. The experimental saturation magnetization is highly consistent with theoretical calculations and Slater-Pauling rule when x < 4, indicating the highly ordered atomic occupation. The magnetization and Curie temperature can be significantly tuned by altering spin polarizations and exchange interactions. The introduction of the foreign atom, Ti, results in a linear increase in residual resistivity, while electron-phonon scattering keeps relatively constant. The maximum values for electrical and thermal transport properties are observed in the stoichiometric Fe2CrV composition.

Investigation of the structural, Electronic and magnetic properties of Mn2PdSn Heusler alloy under hydrostatic pressure

The pressure effect on the structural, electronic and magnetic properties of Mn2PdSn Heusler alloy was investigated by the first-principles full-potential linearized augmented plane wave (FP-LAPW) method based on density functional theory (DFT). The exchange and correlation function has been chosen using generalized gradient approximation (GGA) within the parameterization of Perdew-burke-ernzerhof. The lattice constant, electronic density of state (DOS), and magnetic properties such as total magnetic moment were obtained under pressure. It was determined that the calculated lattice parameters are in good agreement with the literature. The Mn2PdSn is stable in the Hg2CuTi-type structure. Furthermore, we expect an extraordinary occurrence of pressure-induced metallic ferrimagnetism to half-metallic ferromagnetism transition in the cubic phase of Mn2PdSn alloy at hydrostatic pressures of 10 GPa.

Ab-initio study of electronic and optical properties of Zr2NiZ (Z=Al, Ga, In) full Heusler alloys

The half-metallic property of Zr2NiZ (Z = Al, Ga, In) Heusler alloys with the Hg2CuTi-type structure has been studied. In Zr2NiZ (Z = Al, Ga, In) Heusler alloys, it is found that spin up states are metallic and spin down states have the semiconducting band gaps. It shows that these Heusler alloys are half-metallic. From the band structure of spin down state, it is observed that these alloys have the indirect band gap. The non-spin polarised and spin polarized calculations predicted that the ferromagnetic ground state energy is less than the non- magnetic ground state energy which shows that these alloys are ferromagnetic in nature. The total magnetic moments of the Zr2NiZ alloys are calculated to be around 3.0 µB for these Zr2NiZ (Z = Al, Ga, In) Heusler alloys. These alloys obey Slater Pauling rule μt = Zt −18. The optical properties like dielectric function, refractive index, energy loss function, reflectivity, absorption coefficient and extinction coefficients are computed for the first time. For spintronic devices, these alloys may be suitable.

Thermodynamic, mechanical stability, and magneto-electronic features of Ti2-based quaternary Heusler alloys Ti2CoGa1−xCux (x=0, 0.25, 0.5, 0.75, and 1): A DFT investigation

In this work, we have used the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the WIEN2k code combined with the generalized gradient approximation (GGA) of the density functional theory (DFT) to study the structural, elastic, mechanical, electronic, magnetic, and thermodynamic properties of the parent ternary inverse Heusler compounds based on Titanium and Cobalt Ti2CoGa, Ti2CoCu in the Hg2CuTi-type structure and their quaternary alloys Ti2CoGa[Formula: see text]Cux ([Formula: see text], 0.5, 0.75) for the chosen concentrations using a supercell with 16 atoms. We have calculated the structural properties, such as the lattice parameters, bulk modulus, and its first derivative, which are in good agreement with those that have been obtained based on other published theoretical methods. Also, we calculated the elastic constants of the studied Heusler alloys, and we found that these materials are elastically stable, ductile, and anisotropic. Therefore, the electronic and magnetic properties indicate that Ti2CoGa exhibits a half-metallic (HM) ferromagnetic behavior, while Ti2CoCu shows a metal and a non-magnetic (NM) character. Their quaternary alloys are found to be nearly HM ferromagnetic materials, with a magnetic moment mainly due to the atom Ti. Furthermore, the quasi-harmonic Debye model, which incorporates the lattice vibrations, was used to estimate the thermodynamic effects on some macroproperties of the Ti2CoGa[Formula: see text]Cux alloys. Successful results were achieved for the variations of the primitive cell volume, bulk modulus, heat capacities, and Debye temperature with pressure and temperature, respectively, in the ranges of 0–30[Formula: see text]GPa and 0–1400[Formula: see text]K. To our knowledge, no analogous investigations on the mechanical and thermodynamic properties of the Ti2CoGa[Formula: see text]Cux ([Formula: see text], 0.5 and 0.75) alloys have been performed to date. As a result, it is predicted that Ti2CoGa[Formula: see text]Cux Heusler alloys will be promising candidates for actual applications in spintronic devices.

Ab initio investigations of the structure-stability, mechanical, electronic, thermodynamic and optical properties of Ti2FeAs Heusler alloy.

In this study, we employed density functional theory coupled with the full-potential linearized augmented plane-wave method (FP-LAPW) to investigate the structural, electronic, and magnetic properties of the Ti2FeAs alloy adopting the Hg2CuTi-type structure. Our findings demonstrate that all the examined structures exhibit ferromagnetic (FM) behaviour. By conducting electronic band structure calculations, we observed an energy gap of 0.739 eV for Ti2FeAs in the spin-down state and metallic intersections at the Fermi level in the spin-up state. These results suggest the half-metallic (HM) nature of Ti2FeAs, where the Ti-d and Fe-d electronic states play a significant role near the Fermi level. Additionally, the obtained total magnetic moments are consistent with the Slater-Pauling rule (Mtot = Ztot - 18), indicating 100% spin polarization for these compounds. To explore their optical properties, we employed the dielectric function to compute various optical parameters, including absorption spectra, energy-loss spectra, refractive index, reflectivity, and conductivity. Furthermore, various thermodynamic parameters were evaluated at different temperatures and pressures. The results obtained from the elastic parameters reveal the anisotropic and ductile nature of the Ti2FeAs compound. These findings suggest that Ti2FeAs has potential applications in temperature-tolerant devices and optoelectronic devices as a UV absorber.

Structural, mechanical, electronic, thermal, and optical properties of the inverse-Heusler compounds X2RuPb(X = La, Sc): A first-principles investigation

Topological insulators are novel quantum material states with insulating bulk band gaps and topologically protected metallic surface states that have been extensively studied owing to their intriguing properties for spintronic and quantum-computing applications. The structural, mechanical, electronic, thermal, and optical properties of inverse Heusler compounds La2RuPb and, Sc2 RuPb in two Hg2CuTi, Cu2 MnAltype structures were calculated using the full potential linear muffin-tin orbital simulation methodology as implemented in the computer code,which is based on density functional theory.We employed the local-density approximation for the exchange and correlation potential (XC) terms. Consequently, the optical characteristics of La2 RuPb, Sc2 RuPb and elastic constants Cij and their corresponding elastic moduli were computed for the first time. According to our structural calculations, La2 RuPb is more stable in its Hg2 CuTi-type structure than Sc2 RuPb in its Cu2 MnAl-type structure. However, the mechanical characteristics demonstrate their stability in the final stages of elastic deformation.

First-Principles Study of Structural, Electronic, Magnetic and Half-Metallic Properties of Mn2ZrX (X = As, Bi) Full Heusler Alloys

In this paper, the structural, electronic, magnetic, and half-metallic properties of full-Heusler alloys Mn2ZrX ([Formula: see text], Bi) in the Hg2CuTi-type structure have been studied by using the first-principles-based density functional theory (DFT) with the full-potential linearized augmented plane-wave (FP-LAPW) method. Mn2ZrX ([Formula: see text], Bi) compounds are found to be half-metallic ferrimagnets. The calculated total magnetic moments of the Mn2ZrX ([Formula: see text], Bi) alloys are estimated at 01[Formula: see text][Formula: see text] according to the Slater–Pauling rule of [Formula: see text] ([Formula: see text]–24) [Formula: see text]. It was discovered that Mn2ZrAs and Mn2ZrBi maintained their half-metallicity for a lattice constant interval of 5.72 to 6.26 Å and 6.33 to 6.62 Å, respectively, and present a maximum degree of spin polarization at the Fermi level. In addition, the predicted formation energy and elastic parameters show that these materials are mechanically stable. All of these results indicate that these new Mn2-based heusler alloys are able to be the candidates for spintronic applications.

Topologically nontrivial phase in Na2CuX (X= As, Sb, Sn and Bi) full Heusler compounds: Insights from DFT-based computer simulation

The inspection of materials supporting topological excitations is one of the prospective areas of condensed matter physics. This paper is devoted to studying the possibility of the existence of topological phases in Na2CuX (X= As, Sb, Sn and Bi) full Heusler compounds using the FP-LMTO (Full-Potential Linear Muffin-Tin Orbital) method with and without spin-orbit coupling (SOC). The study of structural properties has found that these materials are energetically stable in the Hg2CuTi type structure. Also, formation energy calculations have shown that these materials are convenient to manufacture. Otherwise, band structure calculations show that these materials exhibit the behavior of non-trivial topological materials with a semi-metallic nature. The obtained results in this study, generally, showed that SOC is not a primary cause of the band inversion mechanism.

A DFT study of new full Heusler compound Li2MgC insights into the structural, electronic and thermoelectric properties: A high efficiency performance thermoelectric material

Structural, electronic and thermoelectric properties for full Heusler compound Li2MgC were studied using the full potential linearized augmented plane wave (FP-LAPW) method based on the density functional theory (DFT), implemented in the Wien2k package. The term of the exchange and correlation potential (XC) is treated by the generalized gradient approximation GGA and Trans-Blaha-modified Becke–Johnson (mBJ-GGA). From the various calculations, it emerges that the Cu2MnAl type structure is more suitable for this compound than that of the Hg2CuTi type structure; moreover, this compound is stable in the non-magnetic (NM) state. Furthermore, this compound exhibits a semi -conductor behavior with an indirect band gap at Γ-X direction. The calculated formation and cohesion energies are negative, which clearly and unequivocally indicates the thermodynamic stability of the compound studied and that it can be synthesized experimentally. Otherwise, this compound is characterized by a high figure of merit (ZT) (close to unity), making it a promising candidate for thermoelectric applications.

Phase stability, mechanical, electronic, magnetic and thermodynamic properties of the Pd2PrX(X=Cl, F) compounds: An Ab-initio study

Many of the known examples of half-metallic ferromagnets HMF are oxides, sulfides, or Heusler alloys have attracted some interest for their potential use in spintronics. In order to achieve such understanding we have performed an ab-initio calculations with spin polarization using plane-wave pseudo potential technique based on the density-functional theory (DFT), the exchange-correlation potential was treated with the generalized gradient approximation (PBE-GGA), whereas for the treatment of on-site electron-electron correlations the PBE-GGA+U approximation (where U is the Hubbard Coulomb energy term) are applied for the calculation of the structural, electronic, elastic and magnetic properties of Pd2PrX (X=Cl, F). The results showed that for Pd2PrCl and Pd2PrF, Hg2CuTi-type structure is energetically more stable than Cu2MnAl-type structure at the equilibrium volume. Electronically, Pd2PrCl and Pd2PrF exhibit half-metallicity with small band gaps of 0.06 and 0.25eV respectively with GGA-PBE+U in the spin-down channels whereas spin-up channels are conducting. The calculated total magnetic moment of 2.00 μB per formula unit is very close to integer value and agree well with the Slater-Pauling rules ( Mtot=34-Ztot), where the magnetic moment is basically carried by Pr atoms. However, the elastic properties show that Pd2PrX (X=Cl, F) compounds are ductile and anisotropic according to the analysis of B/G and Cauchy’s pressure. The Thermodynamic properties were also analyzed using the quasi-harmonic Debye model. Both the compounds are found structurally stable.

A potential full Heusler thermoelectric material CO2ZrZ (Z=Al, Si, Ga and Sn) in low temperature: An Ab-initio investigation

The structural, electronic, magnetic, elastic and thermoelectric properties of full-Heusler alloys Co2ZrZ (Z = Al, Si, Ga and Sn) are investigated using the augmented plane wave method (FP-LAPW) based on the framework of spin density functional theory. The term of the exchange and correlation potential (XC), is treated by the generalized gradient approximation GGA and Trans-Blaha-modified Becke–Johnson (TB-mBJ). The results obtained showed that the Cu2MnAl-type structure has more stable energy than the Hg2CuTi-type structure for all the full-Heusler studied. From electronic calculations, it is found that all the compounds studied have an indirect band gap with a half-metallic behavior. Furthermore, we also found that all materials have integral magnetic moments which are mainly due to 100% spin polarization at Fermi energy. The calculated elastic constants and the anisotropy shear factors indicate that these compounds have a ductile character and are mechanically stable. Finally, we calculated the thermoelectric properties by applying Boltzmann theory as implemented in the BoltzTraP code. The results obtained for the merit factor (ZT) and Seebeck coefficient (S) make these materials promising candidates in thermoelectric applications and in spintronics devices.

Structural, electronic, magnetic and mechanical properties of the full-Heusler compounds Ni2Mn(Ge,Sn) and Mn2NiGe

Abstract Mn-Ni based full-Heusler alloys belong to novel half-metallic compounds with a promising set of physical properties for applications as functional materials. Based on first principles calculations, the electronic structures, the magnetic and mechanical properties of Ni2Mn(Ge,Sn) and Mn2NiGe full-Heusler alloys have been investigated in detail. The results revealed that the Mn2NiGe with Hg2CuTi type structure is more stable; on the other hand, for Ni2Mn(Ge,Sn), the Cu2MnAl type structure is more stable. The Mn2NiGe alloys are found to be half-metallic with an integer value of total magnetic moment of 4 μB which makes them interesting materials in the field of spintronics. The Ni2Mn(Ge,Sn) alloys exhibit metallic character in both Hg2CuTi and Cu2MnAl type structures. The calculated B/G ratios for all the considered compounds Ni2Mn(Ge,Sn) and Mn2NiGe are greater than 1.75; therefore, these alloys are ductile, and the calculated Cauchy’s pressure is positive, which also classified these compounds as ductile materials.

First-principles investigation of half-metallic ferromagnetism of Fe2YSn (Y = Mn, Ti and V) Heusler alloys

In this paper, we use the first-principles calculations based on the density functional theory to investigate structural, electronic and magnetic properties of Fe2YSn with (Y = Mn, Ti and V). The generalized gradient approximation (GGA) method is used for calculations. The Cu2MnAl type structure is energetically more stable than the Hg2CuTi type structure. The negative formation energy is shown as the evidence of thermodynamic stability of the alloy. The calculated total spin moment is found as 3μB and 0μB at the equilibrium lattice constant for Fe2MnSn and Fe2TiSn respectively, which agrees with the Slater-Pauling rule of Mt= Zt-24. The study of electronic and magnetic properties proves that Fe2MnSn and Fe2TiSn full-Heusler alloys are complete half-metallic ferromagnetic materials.

Insight view of Hf2CrZ (Z = B, Ga, In, Si, Ge, Sn) Heusler materials via DFT calculations: A study on structural, electronic and magnetic properties

In this study, we have investigated the structural, electronic and magnetic properties of the Hf2CrZ (Z = B, Ga, In, Si, Ge, Sn) full Heusler materials in both Hg2CuTi and Cu2MnAl type structures. These investigations have been carried out by employing the first-principles computational method - full potential (FP) linearized (L) augmented plane-wave plus local orbital (APW + lo) - framed within the density functional theory (DFT) and embodied in WIEN2k computational package. Our investigations show that Cu2MnAl-type structures of the Hf2CrZ (Z = B,Ga,In, Si, Ge, Sn) Heusler compounds are more stable than that of Hg2CuTi-type ones. Our investigations also show that Hg2CuTi type structure of Hf2CrZ Heusler alloys demonstrates half-metallic character for Hf2CrZ (Z = B,Ga, In) with a value of the magnetic moment 1 μB and lower value for Hf2CrZ (Z = Si, Ge, Sn).

Investigations of the stability, electronic and magnetic structures in the Zr2Ni-based Heusler compounds: First principles study

Analysis of stability, electronic and magnetic properties of Heusler alloys Zr2NiZ (Z = Al, Ga, In, B) based on Hg2CuTi type-structures were examined by using first principles calculations (DFT) with full-potential linearized augmented plane-wave method (FP-LAPW). All compounds demonstrate a stable ferromagnetic phase (FM) with half metallic (HM) properties. The energy band gaps (Eg) in spin-minority Fermi energy (Ef) were found to be 0.33 eV, 0.38 eV, 0.54 eV and 0.62 eV, for Zr2NiZ (Z = Al, Ga, In, B) respectively, with spin polarization (SP) of 100%. The calculation of the magnetic moment of these compounds were found to be equal to integer value 3 μB/f.u., which means the compounds obeyed the Slater–Pauling rule(S-P) of Mt = Zt–18. These compounds presented HM properties with full SP over a wide domain lattice constant values. These properties indicate their importance in spintronic applications.

Insight View of Topological Nontrivial Nature in the Novel Alkali Metal–Based Quaternary Heusler Compounds via Ab Initio Calculations

In this paper, we have highlighted a first-principles study of the structural stability and electronic behavior of the novel alkali metal–based quaternary Heusler compounds (LiNaCuAs, LiKCuAs, NaKCuAs, LiRbCuAs, NaRbCuAs, and KRbCuAs), using the full-potential linear muffin-tin orbital (FP-LMTO) method. The obtained results show that our compounds are energetically more stable in the Hg2CuTi-type structure. The calculated electronic properties with and without spin-orbit coupling (SOC) effects indicate that the majority of compounds naturally present a band inversion order which confirmed the topological nontrivial behavior of these materials. In addition, our results show that SOC is not a primary cause of the band inversion mechanism. The obtained values of the calculated formation energy confirm the physical stability of these compounds against decomposition, and they can be passed in fabrication level.

Soft Ferromagnetic Properties of Half-Metallic Mn2CoAl Heusler Alloy Nanoparticles for Spintronics Applications

The ternary full Heusler alloy Mn2CoAl nanoparticles were synthesized by using co-precipitation technique. The as-prepared sample was observed for amorphous nature and further increased at various annealing temperatures (like 700 °C, 800 °C and 900 °C) in argon gas atmosphere for 5 h. X-ray diffraction studies were performed, and the pattern confirms the formation of Hg2CuTi-type structure of the XA or Xα disorder structure. Williamson-Hall plot (W-H plot) was used to find the uniform deformation model so as to get low value of strain-induced broadening. The presence of Mn2CoAl with the particle size ≈ 50 nm was obtained from high-resolution scanning electron microscopy (HR-SEM), and the elemental analysis study confirms the presence of Mn, Co, and Al. UV-Visible absorption spectrum shows the wide absorption peak at 470 nm and the estimated band gap energy value at Eg = 0.8 eV (from Tauc plot) for 900 °C annealed sample. Synthesized Mn2CoAl nanoparticles induced ferromagnetic behavior due to composition deviation and as a result displayed low coercivity of soft magnetic behavior. Half-metallic ferromagnetic Heusler alloys have a wide range of applications from medical imaging to data storage, and also it has profound spintronics applications.

Structural stability, mechanical, electronic and thermal behaviour of Ru2CrZ (Z=Sb, Si, Pb, Ge) Heusler alloys

In this paper, the structural, elastic, electronic properties of Ru2CrZ (Z=Si, Ge, Pb, Sn) are explored using the generalized gradient approximation based on ab initio plane-wave pseudopotential density functional theory. With the help of the quasi-harmonic Debye model, we also investigate the variation of normalized volume V/V0, the heat capacities CV and CP, thermal expansivity, and Debye temperature of Ru2CrZ (Z=Si, Ge, Pb, Sn). Results show that the Cu2MnAl type structure is more stable then Hg2CuTi type structure. The four compounds in the ground state are predicted to be nearly half-metal behavior with total magnetic moment near to the integer value. To provide a comparative and complementary study to future researches, we investigated the elastic and thermodynamic properties.

Theoretical study of structural, electronic, dynamic and thermodynamic properties of Ni2FeAl and Ni2CoAl alloys

First-principles full-potential linearized augmented plane-wave method based on density functional theory (DFT) is used to investigate the structural, electronic, magnetic, dynamical and thermodynamic properties of Ni based full-Heusler alloys Ni2YAl (Y= Fe, Co). These full-Heusler alloys in different types structures Cu2MnAl, Hg2CuTi and I4/mmm were calculated within the Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA-PBE). The tetragonal I4/mmm-type structure is found to be energetically more favorable than the cubic and Cu2MnAl-type and Hg2CuTi-type structures for both the Ni2FeAl and the Ni2CoAl full-Heusler alloys. The calculated lattice parameters, bulk moduli, their first-pressure derivatives and internal parameters are in good agreement with the other theoretical data. Considering the phonon dynamics of Ni2FeAl and Ni2CoAl full-Heusler alloys in Cu2MnAl, Hg2CuTi and I4/mmm phases, we observed that Ni2FeAl full-Heusler alloy in the Cu2MnAl and I4/mmm phases is dynamically stable due to the absence of imaginary modes in phonon dispersion. However, Ni2CoAl full-Heusler alloy is dynamically stable in I4/mmm. The observed magnetism in these alloys is mainly from the 3d states of Co and Fe atoms.

Investigation of Full-Heusler compound Mn2MgGe for magnetism, spintronics and thermoelectric applications: DFT study

First principle method based Density functional theory calculations are used to investigate electronic, magnetic, thermoelectric and lattice-dynamical properties of Full-Heusler compound Mn2MgGe. We considered the energetic, thermodynamical and lattice-dynamical stability criteria for Mn2MgGe by evaluating the total energy, formation energy, and phonon density of states respectively, which thereby suggest that the synthesis of Full-Heusler compound Mn2MgGe is possible. Half metallic spin-polarized nature from electronic band structure and total magnetic moment (2μB) of Hg2CuTi type structure of Mn2MgGe potentially facilitate its spintronics applications. The results of electronic structure and magnetism predicts that Hg2CuTi type structure of Mn2MgGe is an indirect band gap semiconductor with half-metallic ferrimagnetic behaviour. Antiparallel and equal magnetic moment of Mn atoms cancel out the magnetization in Cu2MnAl type structure of Mn2MgGe, making its total magnetic moment 0 μB/cell. The electronic and magnetic properties for Cu2MnAl type structure of Mn2MgGe has not been previously reported. Positive and negative value of Seebeck coefficient for spin up and spin down channel indicate the presence of P-type and N-type charge carriers in the compound. Mn2MgGe exhibits high Seebeck coefficient −38 μV/K and 180 μV/K in spin-up and spin-down channel at room temperature (300 K) along with huge power factor of 4.23×1011 w/mK2s at 600 K, predicting Mn2MgGe as a potential candidate for thermoelectric applications.