Lattice Mismatch Research Articles

First-principles calculations for heterostructure studies Involving CsPbI3 perovskite and IV-VI semiconductors

The PbX(X = S, Se, Te)/CsPbI3 heterostructure, formed by lead chalcogenides and halide perovskite CsPbI3, holds promise for optoelectronic devices. Utilizing first-principles calculations with VASP software, this study investigates its structural, electronic, and optical properties. With confirmed appropriate lattice mismatch rates (4.6%, 2.4%, 3.8%) and similar octahedral frameworks, constructing the PbX/CsPbI3 heterostructure is feasible. Calculations of electronic properties reveal mechanisms to improve optical performance. The type-I band alignment at the PbX/CsPbI3 interface(−5.27 eV < PbX < −3.73 eV, −5.34 eV < CsPbI3 < −3.57 eV) reduces electron and hole recombination losses, enhancing energy transfer efficiency. This arrangement facilitates electron and hole transfer from CsPbI3 to PbX, supported by charge density differences. Among the three heterostructures, PbSe/CsPbI3 demonstrates superior charge transfer capabilities, with more pronounced electron clouds. The PbX/CsPbI3 heterostructure extends CsPbI3’s light absorption into the near-infrared via PbX influence. Spectral comparison reveals PbTe/CsPbI3 > PbSe/CsPbI3 > PbS/CsPbI3, with PbSe/CsPbI3 excelling in stability, charge density transfer, and optical properties. Furthermore, under the premise of ensuring stability, different optical absorption characteristics can be achieved by adjusting the composition of Se atoms in PbSe/CsPbI3. This work provides a theoretical basis for the physical mechanisms behind enhancing the performance of PbX/CsPbI3 heterostructures as visible-to-near-infrared optoelectronic materials. It offers a promising avenue for the design of high-performance visible-to-near-infrared optoelectronic materials.

Mid-infrared detectors for space electronics based on InAs-core/InP-shell nanowires

The Mid-Infrared (MIR) spectral range is most important for free-space communications and astronomy. It contains radiation emitted by astrophysical objects during evolution of the planets, stars, galaxies and in particular by prebiosignature molecules on exoplanets. Nanowires (NWs) are expected to improve various optoelectronic devices, including IR photodetector technology. The bandgap of the catalystless InAs NWs can be tuned by introducing mechanical strain due to lattice mismatches in the core/shell NWs structures. Passivation with wider bandgap InP shell provide highly tunable functionality for future electronic devices. Temperature dependence of photoluminescence (PL) spectra of NWs InAs and InAs-core/InP-shell was acquired using Fourier-spectrometer. The position of the high-energy PL peak between calculated values of Eg for wurtzite and sphalerite structures confirms the formation of NWs into a combined polytype. Low energy PL peak is connected with parasitic bulk islands. Surface passivation successfully eliminates surface states and provides nontrivial temperature dependence of high-energy PL peak due to tensile and compressive strain in InAs core. Thus, detectors based on NWs InAs and InAs-core/InP-shell structures can operate in the MIR range of the spectrum with a wavelength from 2 to 5 μm.

Elucidating effects of Eu and P on solidification and precipitation of Al-7Si-0.3Mg based alloys refined by Ta and TiB2

Effects of Eu (up to 500 ppm) and P (up to 40 ppm) on solidification and precipitation of Al-7Si-0.3Mg based alloys refined by solute Ta (0.12 wt%) and stochiometric Al-2.2Ti-1B grain refiner were investigated using optical microscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) as well as density functional theory (DFT) calculations. It was found that (i) solute Ta can refine α-Al grains and is unaffected by the addition of Eu and/or P. (ii) 200 ppm Eu is eligible enough to modify eutectic Si although its modification effect can be enhanced with higher Eu additions (up to 500 ppm). (iii) A high P concentration (40 ppm) counteracts the modification effect in the alloy modified with 200 ppm Eu and therefore unmodified structure is obtained. (iv) Even with the addition of Eu and P, the activation energy of stable β-Mg2Si is calculated to be very low (60–70 kJ/mol), indicating a short time for the precipitation of β-precipitates. Furthermore, one possible nucleation sequence in Al-Si-Mg based alloys modified with Eu or Sr has been proposed based on the lattice mismatch calculation and thermodynamic stability. Finally, DFT calculations suggest that Eu is energetically favourable for TPRE growth mechanism. The present investigation provides new insights into controlling solidification microstructure (mainly for the grain refinement of α-Al and eutectic grains) and precipitation microstructure (mainly for β-MgSi precipitate) of Al-7Si-0.3Mg based alloys via the addition of Ta and TiB2 as a refiner of α-Al and the addition of Eu and P as a modifier of eutectic Si.

Axially lattice-matched wurtzite/rock-salt GaAs/Pb1−xSnxTe nanowires

We investigate the full and half-shells of Pb1−xSnxTe topological crystalline insulator deposited by molecular beam epitaxy on the sidewalls of wurtzite GaAs nanowires (NWs). Due to the distinct orientation of the IV–VI shell with respect to the III–V core the lattice mismatch between both materials along the nanowire axis is less than 4%. The Pb1−xSnxTe solid solution is chosen due to the topological crystalline insulator properties above some critical concentrations of Sn (x ≥ 0.36). The IV–VI shells are grown with different compositions spanning from binary SnTe, through Pb1−xSnxTe with decreasing x value down to binary PbTe (x = 0). The samples are analysed by scanning transmission electron microscopy, which reveals the presence of (110) or (100) oriented binary PbTe and (100) Pb1−xSnxTe on the sidewalls of wurtzite GaAs NWs.

Sliding friction of a pillar array interface: part I.

Biology is replete with examples, at length scales ranging from the molecular (ligand-receptor binding) to the mesoscopic scale (wing arresting structures on dragonflies) where shape-complementary surfaces are used to control interfacial mechanical properties such as adhesion, friction, and contact compliance. Related bio-inspired and biomimetic structures have been used to achieve unique interfacial properties such as friction and adhesion enhancement, directional and switchable properties. The ability to tune friction by altering surface structures offers advantages in various fields, such as soft robotics and tire manufacturing. Here, we present a study of friction between polydimethylsiloxane (PDMS) samples with surfaces patterned with pillar-arrays. When brought in contact with each other the two samples spontaneously produce a Moiré pattern that can also be represented as an array of interfacial dislocations that depends on interfacial misorientation and lattice spacing. Misorientation alone produces an array of screw dislocations, while lattice mismatch alone produces an array of edge dislocations. Relative sliding motion is accompanied by interfacial glide of these patterns. The frictional force resisting dislocation glide arises from periodic single pillar-pillar contact and sliding. We study the behavior of pillar-pillar contact with larger (millimeter scale) pillar samples. Inter-pillar interaction measurements are combined with a geometric model for relative sliding to calculate frictional stress that is in good agreement with experiments.

Effect of types of calcium-containing alloy on non-metallic inclusions in high-Al steel

The influence of different calcium-containing alloys on inclusions in high-Al steel is investigated in the current study. The effects of SiCa, AlCa20, AlCa75 and FeSi alloys on the modification of solid inclusions in molten steel are compared, and the mechanism of inclusion evolution is revealed based on the non-uniform distribution of elements and the lattice mismatch between the inclusion particles. The results show that the Ca yield of FeSi alloy is 26%, which is significantly higher than that of other alloys (&lt;5%). In addition, the calcium treatment by FeSi alloy causes less aspiration of molten steel, which is conducive to avoiding the increase of AlN in high-Al steel. After calcium treatment, the primary Al2O3 particles in steel are transformed into CaO-Al2O3-CaS and CaO-Al2O3-MgO complex inclusions, while AlN can only be precipitated in the form of a single particle, or precipitated from the transformed CaO · 2Al2O3 oxide. In general, FeSi alloy has the best effect on the modification of Al2O3 inclusions, which can maximize the transformation of solid particles into liquid inclusions in steel liquid without introducing too much impurities.

Second-harmonic generation in 2D moiré superlattices composed of bilayer transition metal dichalcogenides.

Moiré superlattices (MSLs) in twisted two-dimensional van der Waals materials feature twist-angle-dependent crystal symmetry and strong optical nonlinearities. By adjusting the twist angle in bilayer van der Waals materials, the second-harmonic generation (SHG) can be controlled. Here, we focus on exploring the electronic and SHG properties of MSLs in 2D bilayer transition metal dichalcogenides (TMDs) with different twist angles through first-principles calculations. We constructed MSL structures of five TMD materials, including three single-phase materials (MoS2, WS2, and MoSe2) and two heterojunctions (MoS2/MoSe2 and MoS2/WS2) with twist angles of 9.4°, 13.2°, 21.8°, 32.2°, and 42.1° without lattice mismatch. Our findings demonstrate a consistent variation in the SHG susceptibility among different TMD MSLs as a response to twist-angle changes. The underlying reason for the twist-angle dependence of SHG is that the twist angle regulates the interlayer coupling strength, affecting the optical band gap of MSLs and subsequently tuning the SHG susceptibility. Through a comparison of the static SHG susceptibility values, we identified the twist angle of 9.4° as the configuration that yields the highest SHG susceptibility (e.g. 358.5 pm V-1 for the 9.4° MoSe2 MSL). This value is even twice that of the monolayer (173.3 pm V-1 for monolayer MoSe2) and AA'-stacked bilayer structures (139.8 pm V-1 for AA' MoSe2). This high SHG susceptibility is attributed to the strong interlayer coupling in the 9.4° MSL, which enhances the valence band energy (contributed by the antibonding orbitals of chalcogen-pz and transition metal-dz2) and consequently leads to a small optical band gap, thus improving the optical transitions. The findings of this study provide a straightforward way to improve the SHG performance of bilayer TMDs and also throw light on the sensitive relationship between the twist angle, band structure and SHG properties of TMD MSLs.

Near-surface electronic structure in strained Ni-ferrite films: An x-ray absorption spectroscopy study

We report on the x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism (XMCD) of a series of NiFe2O4 (Ni ferrite) films grown on symmetry matched substrates and measured in two geometries: out-of-plane and near in-plane. The Ni ferrite films, grown by pulsed laser deposition, are epitaxial and the substrates used (ZnGa2O4, CoGa2O4, MgGa2O4, and MgAl2O4) introduce a systematic variation in the lattice mismatch between the substrate and the film. Modeling of the XAS and XMCD spectra, both measured with the surface sensitive total electron yield mode, indicates that the Ni2+ cations reside on the octahedrally coordinated lattice sites in the spinel structure. Analyses of the Fe XAS and XMCD spectra are consistent with Fe3+ cations occupying a subset of the octahedral and tetrahedral sites in the spinel oxide lattice with the addition of a small amount of Fe2+ located on octahedral sites. The Ni2+ orbital to spin moment ratio (μℓ/μs), derived from the application of XMCD sum rules, is enhanced for the substrates with a small lattice mismatch relative to NiFe2O4. The results suggest a path for increasing the orbital moment in NiFe2O4 by applying thin film growth techniques that can maintain a highly strained lattice for the NiFe2O4 film.

The growth of Ge and direct bandgap Ge1-xSnx on GaAs (001) by molecular beam epitaxy.

Germanium tin (GeSn) is a tuneable narrow bandgap material, which has shown remarkable promise for the industry of near- and mid-infrared technologies for high efficiency photodetectors and laser devices. Its synthesis is challenged by the lattice mismatch between the GeSn alloy and the substrate on which it is grown, sensitively affecting its crystalline and optical qualities. In this article, we investigate the growth of Ge and GeSn on GaAs (001) substrates using two different buffer layers consisting of Ge/GaAs and Ge/AlAs via molecular beam epitaxy. The quality of the Ge layers was compared using X-ray diffraction, atomic force microscopy, reflection high-energy electron diffraction, and photoluminescence. The characterization techniques demonstrate high-quality Ge layers, including atomic steps, when grown on either GaAs or AlAs at a growth temperature between 500-600 °C. The photoluminescence from the Ge layers was similar in relative intensity and linewidth to that of bulk Ge. The Ge growth was followed by the growth of GeSn using a Sn composition gradient and substrate gradient approach to achieve GeSn films with 9 to 10% Sn composition. Characterization of the GeSn films also indicates high-quality gradients based on X-ray diffraction, photoluminescence, and energy-dispersive X-ray spectroscopy measurements. Finally, we were able to demonstrate temperature-dependent PL results showing that for the growth on Ge/GaAs buffer, the direct transition has shifted past the indirect transition to a longer wavelength/lower energy suggesting a direct bandgap GeSn material.

A study on the Si1-xGex gradual buffer layer of III-V/Si multi-junction solar cells based on first-principles calculations.

III-V/Si multi-junction solar cells have been widely studied in recent years due to their excellent theoretical efficiency (∼42%). In order to solve the problem of lattice mismatch between Si and III-V compounds of III-V/Si solar cells, different hexagonal Si1-xGex buffer layer models on the surface of hexagonal diamond Si(001) were built, and the structural, electronic and optical properties of the proposed models were calculated based on first principles calculations. The results showed that all models of the designed buffer layer could effectively reduce the lattice mismatch, and the buffer layer hex-Si1-xGex (x = 0, 0.75, and 1) is the ideal model and has achieved the best lattice-matching improvement with high defect formation energy, as well as direct band gap properties and a larger light adsorption coefficient. These theoretical models, with their analyzed properties, could offer a promising pathway toward realizing high efficiency and low cost III-V/Si multi-junction solar cells.

Permissible domain walls in monoclinic MAB ferroelectric phases.

The concept of monoclinic ferroelectric phases has been extensively used over recent decades for the understanding of crystallographic structures of ferroelectric materials. Monoclinic phases have been actively invoked to describe the phase boundaries such as the so-called morphotropic phase boundary in functional perovskite oxides. These phases are believed to play a major role in the enhancement of such functional properties as dielectricity and electromechanical coupling through rotation of spontaneous polarization and/or modification of the rich domain microstructures. Unfortunately, such microstructures remain poorly understood due to the complexity of the subject. The goal of this work is to formulate the geometrical laws behind the monoclinic domain microstructures. Specifically, the result of previous work [Gorfman et al. (2022). Acta Cryst. A78, 158-171] is implemented to catalog and outline some properties of permissible domain walls that connect `strain' domains with monoclinic (MA/MB type) symmetry, occurring in ferroelectric perovskite oxides. The term `permissible' [Fousek & Janovec (1969). J. Appl. Phys. 40, 135-142] pertains to the domain walls connecting a pair of `strain' domains without a lattice mismatch. It was found that 12 monoclinic domains may form pairs connected along 84 types of permissible domain walls. These contain 48 domain walls with fixed Miller indices (known as W-walls) and 36 domain walls whose Miller indices may change when free lattice parameters change as well (known as S-walls). Simple and intuitive analytical expressions are provided that describe the orientation of these domain walls, the matrices of transformation between crystallographic basis vectors and, most importantly, the separation between Bragg peaks, diffracted from each of the 84 pairs of domains, connected along a permissible domain wall. It is shown that the orientation of a domain wall may be described by the specific combination of the monoclinic distortion parameters r = [2/(γ - α)][(c/a) - 1], f = (π - 2γ)/(π - 2α) and p = [2/(π - α - γ)] [(c/a) - 1]. The results of this work will enhance understanding and facilitate investigation (e.g. using single-crystal X-ray diffraction) of complex monoclinic domain microstructures in both crystals and thin films.

Phonon dynamic behaviors induced by amorphous layers at heterointerfaces.

An amorphous layer is commonly found at the interfaces of heterostructures due to lattice and thermal mismatch between dissimilar materials. While existing research has explored the impact of these layers on interfacial thermal transport, a comprehensive understanding of the underlying microscopic mechanisms remains essential for advancing thermal nanodevice development. Through phonon wave packet simulations, we investigated the dynamic behaviors of phonons crossing the amorphous interlayer at the GaN/AlN interface from the mode level. Our results highlight the amorphous layer's capability to notably adjust the polarization properties of incoming phonons, culminating in phonon localization. By examining transmission outcomes on a per-mode basis, we demonstrate the amorphous layer's impediment on phonon transport. Notably, this resistance escalates with an increase in the amorphous layer thickness (L), with certain high-frequency TA phonons showing unexpectedly high transmissivity due to polarization conversion and inelastic scattering at the amorphous interface. In addition, we observe that the amorphous layer prompts multiple reflections of incident phonons, instigating discernible from the two-beam interference equation. Finally, in pursuit of enhanced phonon transport, we employ annealing techniques to optimize the interface morphology, leading to the recrystallization of the amorphous layer. This optimization yields a substantial enhancement of interfacial thermal conductance by up to 38% for L = 3 nm.

Graphite nucleation on (Al, Si, Mg)-nitrides: Elucidating the chemical interactions and turbostratic structures in spheroidal graphite cast irons

The ubiquitous (Al,Si,Mg)-nitride has been the focus of recent investigations of spheroidal graphite irons. In particular, because they have been systematically found in the nucleus of graphite spheroids. Despite having a similar crystal structure as graphite, their lattice parameter is vastly different. Since the crystallographic match is mainly used to justify the potential of nucleation sites, challenges have been encountered to explain the mechanism of graphite nucleation in this type of inclusion (microparticle). The present work reports the structure, composition, and interactions of these (Al,Si,Mg)-nitrides with graphite and other compounds, such as (Zr,Ti,Nb)-carbonitrides. The latter were the only inclusions with Zr that could be found, while the former inclusion could also be found in the core of graphite. The results confirm that the graphite layers close to the surface of the (Al,Si,Mg)-nitrides have a turbostratic structure. Organized graphite layers are only observed far away from the nitride nucleus. Density functional theory simulations of this interface showed that the interaction between the first graphene layers and the (Al,Si,Mg)-nitrides has a covalent nature, which could explain the turbostratic structure of the inner part of the graphite nodule. Therefore, nucleation of graphite on nuclei with a large lattice mismatch (low planar misfit) may be facilitated by the covalent bonding of carbon atoms on this substrate. These results explain the observed disorder at the interface as well as the deformation of the graphene layers.

Analysis of dislocation defects in compositionally step-graded α-(Al x Ga1-x )2O3 layers.

The ultra-wide bandgap semiconductor α-Ga2O3 can be heteroepitaxially grown on a sapphire substrate. However, due to a lattice mismatch of about 4.6% with a sapphire substrate, many dislocation defects occur in α-Ga2O3 films. To reduce the dislocation density, compositionally step-graded α-(Al x Ga1-x )2O3 layers were fabricated on a c-plane sapphire substrate using mist CVD. TEM measurements revealed few dislocations in the initial layer of α-(Al0.96Ga0.04)2O3, but numerous dislocations were observed in the subsequent layer of α-(Al0.84Ga0.16)2O3. However, the step-graded α-(Al x Ga1-x )2O3 layers exhibited bending of the dislocations under both compressive and tensile strains due to compositional differences of α-(Al x Ga1-x )2O3, resulting in about 50% reduction of the dislocation density in the high-Ga-composition layer of α-(Al x Ga1-x )2O3. The introduction of multiple 50 nm α-Ga2O3 layers into the compositionally step-graded α-(Al x Ga1-x )2O3 layers resulted in a notable reduction in dislocation defects at the interface between the sandwiched α-Ga2O3 layers. It is assumed that the dislocations were bent by the strain caused by the composition change, resulting in a decrease in the number of dislocations. It is anticipated that further reduction of dislocation density will be achieved by optimizing the composition change and thicknesses of layers that provide effective strain for dislocation bending, and by stacking these layers.

GeSn-on-GaAs with photoconductive carrier lifetime >400 ns: role of substrate orientation and atomistic simulation.

Group IV GeSn quantum material finds application in electronics and silicon-compatible photonics. Synthesizing these materials with low defect density and high carrier lifetime is a potential challenge due to lattice mismatch induced defects and tin segregation at higher growth temperature. Recent advancements in the growth of these GeSn materials on Si, Ge, GaAs, and with substrate orientations, demonstrated different properties using epitaxial and chemical deposition methods. This article addresses the effect of GaAs substrate orientation and misorientation on the materials' properties and carrier lifetimes in epitaxial Ge0.94Sn0.06 layers. With starting GaAs substrates of (100)/2°, (100)/6°, (110) and (111)A orientations, Ge0.94Sn0.06 epitaxial layers were grown with an intermediate Ge buffer layer by molecular beam epitaxy and analyzed by several analytical tools. X-ray analysis displayed good crystalline quality, and Raman spectroscopy measurements showed blue shifts in phonon wavenumber due to biaxial compressive strain in Ge0.94Sn0.06 epilayers. Cross-sectional transmission electron microscopy analysis confirmed the defect-free heterointerface of Ge0.94Sn0.06/Ge/GaAs heterostructure. Minority carrier lifetimes of the unintentionally doped n-type Ge0.94Sn0.06 epilayers displayed photoconductive carrier lifetimes of >400 ns on (100)/6°, 319 ns on (100)/2°, and 434 ns on (110) GaAs substrate at 1500 nm excitation wavelength. On the other hand, Ge0.94Sn0.06 layer showed poor carrier lifetime on (111)A GaAs substrate. The observed differences in carrier lifetimes were correlated with the formation energy of the Ge on (100)/6° and (100)/2° GaAs heterointerface using Stillinger-Weber interatomic potential model-based atomistic simulation with different heterointerfacial bonding by Synopsys QuantumATK tool. Total energy computation of 6280-atom Ge/GaAs supercell on (100)/6° leads to lower formation energy than (100)/2°, making it more thermodynamically stable. Hence, the growth of the GeSn/III-V material system using misoriented (100) substrates that are more thermodynamically stable will enhance the performances of optoelectronic devices.

Structural optimization and engineering of InxGa1−xN quantum dot intermediate band solar cells with intrinsic GaN interlayers

We proposed an optical structure to enhance photoelectric efficiency by optimizing 1 nm i-GaN layers to compensate for lattice mismatch from the In0.5Ga0.5N/GaN layer and absorb excess strain, boosting efficiency.

First-principles study on electronic structure of GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure

Constructing Type-II heterostructure is an effective scheme to tailor the electronic structure and improve the application performance. Motivated by recently successful syntheses of Mg(OH)&lt;sub&gt;2&lt;/sub&gt; and GaS monolayers, we investigate the stability, electronic, and optical properties of GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure by using the density functional theory method. The calculated results show that GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure is easily constructed due to its small lattice mismatch, negative binding energy, and thermodynamic stability. Compared with monolayer materials, the GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure has a band gap that effectively decreases to 2.021 eV and has Type-II band structure, facilitating the spatial separation of photo-generated carriers where electrons are localized in the GaS and holes reside in the Mg(OH)&lt;sub&gt;2&lt;/sub&gt; monolayers. The built-in electric field induced by the interlayer charge transfer points from GaS to Mg(OH)&lt;sub&gt;2&lt;/sub&gt; monolayer, which can further improve the separation and suppress the recombination of electron-hole pairs. Under the biaxial strain, the valance band maximum and conduction band minimum of GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure shift in the downward direction to different extents, resulting in obvious change of band gap, with the change reaching about 0.5 eV. Furthermore, the band structure of GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure can be transformed from indirect band gap semiconductor into direct band gap semiconductor under the tensile strain, while GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure maintains Type-II band structure. Additionally, the band edge positions of GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure can also be effectively adjusted to cross the redox potentials of water decomposition at pH = 0–7. The light absorption spectra show that GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure has stronger light absorption capability than the constituent monolayers. Especially, the light absorption has an obvious redshift phenomenon at a tensile strain of 3%. These findings indicate that the GaS/Mg(OH)&lt;sub&gt;2&lt;/sub&gt; heterostructure has a wide range of applications in the field of optoelectronics due to the tunable electronic properties, and also provides some valuable insights for future research.

Promoting fast potassium storage in CoSe2/VSe2 non-layered/layered heterostructured nanofibers

A heterostructure of non-layered CoSe2 and layered VSe2 was designed to enhance K storage. The lattice mismatch created significant distortion at phase boundaries, facilitating K diffusion and improving electrochemical performance in PIBs.

Designing ultrathin and long ferromagnetic nanowires array for Tunable-Range Majorana zero mode studies

We have conducted a study that focuses on designing a quasi-1D ultrathin and long ferromagnetic nanowires array with excellent linearity. The purpose of this design is to test the presence of Majorana zero modes in pairs over a long distance and the influence of the lateral interaction. Specifically, we investigate the magnetic properties of a one-unit cell thick MoSX nanowire array, where dopant X (H, C, N, O, and F. etc) is utilized, to assess its suitability for our intended purposes. Our findings reveal that the edge magnetization of the optimized MoSX nanowires is comparable to that of 3d transition metals with the Curie transition temperature surpassing room temperature. Our study indicates that the ferromagnetism of the optimized MoSX nanowires is unlikely to be eliminated when placed on an s-wave superconductor due to lattice mismatch. By conducting comparative case studies of various dopants, we establish a connection between the source of magnetism in the nanowires and internal electric fields, charge perturbation, spin-orbital coupling and p-d hybridization. The strong exchange interaction, robust spin-orbital coupling and large local magnetic moment exhibited by long and ultrathin room-temperature ferromagnetic nanowires open up avenues for diverse topological applications.

Enhancing optical properties through zinc halide precursor selection: interfacial optimization of InZnP quantum dots

QDs with a core structure synthesized using highly reactive zinc chloride, exhibited increased Zn–O bonds, effectively reducing the inherent surface defects in InP, minimizing the lattice mismatch, and enhancing the QY of InZnP/ZnS QDs.