The half-Heusler compound TaFeSb has been reported to exhibit promising p $p$ -type thermoelectric properties. Here, a high and reproducible thermoelectric figure of merit (zT) of 1.55 with Ti substitution has been reported. It is demonstrated that the zT enhancement is not solely an effect of carrier optimization; the role of antisite disorder is also shown to be pivotal. To demonstrate this, samples are prepared with controlled stoichiometry to tune the disorder. The thermoelectric power factor was found suppressed in samples with only a nominal disorder, which also enhanced the lattice thermal conductivity, leading to a low zT of ∼ 1 $\sim\!\! 1$ . However, with Fe deficiency, which is shown to increase the antisite disorder, we observed an increase in the Seebeck effective mass, leading to enhanced power factor and reduced lattice thermal conductivity, resulting in a zT of 1.35, i.e., a ≃ 35 $\simeq 35$ % enhancement over the ordered sample. A further increase in zT is observed for the arc-melted sample, where disorder is more pronounced, resulting in a zT of 1.55. These findings provide valuable insights for optimizing the thermoelectric performance of half-Heusler materials through controlled defect engineering.

This work investigates the electric, thermal, and thermoelectric responses of a rotating pion gas of finite transverse radius in the presence of a background magnetic field, with the rotation axis aligned with the magnetic field. We explicitly calculate the parameter limits for π^+ condensation and restrict our working regime safely outside these boundaries, ensuring well-behaved transport coefficients. Notably, the system exhibits a condensation asymmetry, with π^- remaining uncondensed at the parameters that induce π^+ condensation. Using the Boltzmann Transport Equation under the Relaxation Time Approximation, we calculate the longitudinal electrical conductivity, thermal conductivity, and the Seebeck coefficient. Our results reveal a competing interplay between the magnetic field and rotation, highlighting the substantial impact of rotation on the medium's transport properties: while the magnetic field suppresses the transport coefficients in a static medium, rotation, acting as an effective chemical potential, introduces an energy shift that favors their increase. Beyond an angular velocity, this rotational enhancement overpowers the magnetic suppression, leading to an increase in the transport coefficients with increasing magnetic field. Finally, we analyze the relative significance of charge and heat transport through the Lorenz number, providing further insight into the transport characteristics of the rotating magnetized pion medium.

This study evaluates the efficacy of 50 Hz Half-sine Pulsed DC (HSPDC), a readily available but unexplored pulse waveform, against Steady DC (SDC) across voltage regimes using alkaline water electrolysis (AWE) as a model system. The HSPDC outperforms SDC in the explored plasma regime experimental conditions, exhibiting similar to 90%-179% higher energy efficiency, due to the dominance of efficacious plasma microenvironment contributions, as corroborated by optical emission spectroscopy (Le. similar to 1.4x electron density and similar to 1.5x excitation temperature w.r.t. SDC at similar to 70 watts of power input). However, in the explored low-voltage regime experimental conditions (6-26 Voltsms), the energy efficiency of the HSPDC is similar to 20%-32% lower.

Double half-Heusler (DHH) alloys (XY0.5Y '(0.5)Z) stabilized by mixing two unstable HHs (XYZ and XY ' Z) have been the subject of extensive research as an alternative to HHs for high-temperature thermoelectric applications because of the former's low lattice thermal conductivity. In this work, using a combination of density functional theory (DFT)-based calculations and semiclassical Boltzmann transport theory, we elucidate the role of hierarchical bonding, reduction of electronegativity of X, and chemical pressure induced by variation in its atomic size on the electronic properties, transport, and thermoelectric properties, of a family of DHH compounds, namely, XFe0.5Ni0.5Sb (where X = Ti, Zr, and Hf). Compared to the parent compounds, we observe a larger variation in the nature of the bonds in the DHH lattice that aids in the reduction of their lattice thermal conductivity. Our calculations show that electronegativity in the X element and chemical pressure influence the band convergence observed in the conduction band of these materials in a reverse way. While reduction of electronegativity favors band convergence, tensile strain induced in the lattice due to the larger size of X is detrimental for the same. However, electronegativity has a much stronger effect. We observe that HfFe0.5Ni0.5Sb, which shows the largest band convergence, has the highest value of zT for n-type charge carriers among the three materials considered in our work. Moreover, hole-doped (p-type) HfFe0.5Ni0.5Sb also exhibits zT > 1. Therefore, we envisage that HfFe0.5Ni0.5Sb can be a good candidate for both the n and p legs of a thermoelectric device.

High-entropy alloys (HEAs) have gained significant attention recently due to their exceptional physical properties. Among HEAs, entropy-stabilized alloys, where the high configurational entropy drives the structural stability, are of considerable interest in new materials discovery. Here, we combine theoretical and experimental approaches to design very low lattice thermal conductivity (kappa l) high-entropy materials (TiHf)1/2(Fe1-x CoNi1+x )1/3Sb belonging to the half-Heusler family. We demonstrate that (TiHf)1/2(FeCoNi)1/3Sb is entropy-stabilized, with kappa l at 300 K suppressed by over 80% with respect to the parent compound TiCoSb that has an unfavorably high thermal conductivity of 18 Wm-1K-1. Further reduction of kappa l is achieved by tuning the Fe/Ni ratio. The lowest kappa l is observed in the material (TiHf)1/2(Fe0.5CoNi1.5)1/3Sb, where it approaches the theoretical minimum value of kappa min approximate to 1 W-1K-1 at 973 K. Tuning the Fe/Ni ratio simultaneously optimizes the carrier concentration, resulting in significantly enhancing electronic properties. The electrical conductivity increases almost 5-fold, and the power factor increases from 7 to 16 mu Wcm-1K-2 as x increases from 0 to 0.5 at 973 K, making the material (TiHf)1/2(Fe0.5CoNi1.5)1/3Sb achieve a zT of 0.51 at 973 K without further optimization.

Terahertz (THz) magnonics represents the notion of mathematical algebraic operations of magnons such as addition and subtraction in the THz regime-an emergent dissipationless ultrafast alternative to existing data processing technologies. Spin waves on antiferromagnets with a twist in spin-order host, such magnons in the THz regime, possess advantages of higher processing speeds, additional polarization degrees of freedom, and longer propagation lengths compared to gigahertz magnons in ferromagnets. While interactions among THz magnons are the crux of algebra operations, these require magnetic orders with closely spaced magnon modes for easier experimental realization of their interactions. Herein, a rich wealth of magnons spanning a narrow energy range of 0.4-10 meV is unraveled in Co4Ta2O9 using magneto-THz spectroscopy. A rare multitude of ten excitation modes, either of magnons or hybrid magnon-phonon modes, is presented. Among other attributes, spin-lattice interactions suggest a correlation among spin and local lattice distortion, magnetostriction, and magnetic exchange interactions, signifying a THz magnetoelectric effect. This unification of structural, magnetic, and dielectric facets, and their magnetic field control in a narrow spectrum unravels the mechanism underneath the system's complexity, while the manifestation of a multitude of spin-excitation modes is a potential source to design multiple channels in spin-wave computing-based devices.

While significant attention has been devoted to studying entanglement in photonic systems, solid-state spin lattices remain relatively underexplored. Motivated by this gap, we investigate the entanglement structure of one-dimensional ferrimagnetic chains composed of alternating spin-1/2 and spin-3/2 particles. We characterize the ground-state correlations using exact diagonalization and the density matrix renormalization group method. Although the bipartite entanglement is restricted to nearest neighbors, we reveal the presence of long-range genuine multipartite entanglement between spatially separated spin pairs. These findings advance our understanding of quantum correlations in ferrimagnetic materials. The micromagnon description allows us to provide fast approximation of ground states of ferrimagnets and emphasizes the presence of multipartite correlations not widely discussed thus far.

Multilayer graphene (MLG) interconnects, enabled by subtractive etching and intercalation doping, have emerged as a promising solution for advanced Complementary Metal-Oxide-Semiconductor (CMOS) technology nodes, where conventional metal interconnects face escalating challenges, including increased resistance, self-heating, electromigration, and integration complexity. However, traditional MLG synthesis methods typically require high temperatures (>600 °C) and involve transfer from metal catalysts to dielectric substrates-practices incompatible with CMOS back-end-of-line (BEOL) thermal budgets (<500 °C) and prone to introducing defects and wrinkles that hinder wafer-scale integration. To overcome these limitations, this group pioneered a CMOS-compatible, transfer-free growth technique based on pressure-assisted solid-phase diffusion, which enables direct synthesis of high-quality MLG within BEOL constraints. Combined with optimized intercalation doping - originally introduced by this group - this approach achieves significantly enhanced electrical conductivity, exceeding that of sub-30 nm metal wires, with excellent electromigration reliability. This breakthrough has garnered broad attention for its potential to transform interconnect technology and accelerate the integration of graphene into mainstream semiconductor manufacturing. This article presents the scientific rationale, materials physics, and process innovations underpinning this scalable technology, highlighting how catalyst selection, carbon sources, and process parameters govern MLG quality and performance. Beyond interconnects, this work lays a foundation for deploying graphene in optoelectronics, spintronics, photovoltaics, and flexible electronics.

Terahertz spin wave-based computation necessitates the expansion of magnonic based material base, preferably the non-collinear antiferromagnetic spin-configured systems. Using magneto-terahertz time-domain spectroscopy, we revealed a wide range of low-energy antiferromagnetic resonances in a honeycomb magnet Co 4 Ta 2 O 9 , including magnons, phonons, and hybridized spin-phonon coupled modes.

Titanium alloys play a prominent role as metallic biomaterials in the biomedical sector, particularly for implant applications. Various types of Ti alloys are suitable for medical treatment, including Ti6Al4V (Ti64) alloys, which are extensively utilized in biomedical implant materials. This preference was attributed to their commendable strength, excellent corrosion and wear resistance, and satisfactory biocompatibility. Nonetheless, implants produced through diverse additive manufacturing (AM) methods or commercially available methods face performance-related challenges, including mechanical, wear resistance, corrosion resistance, wettability, and biocompatibility. To address these limitations, researchers have actively sought ways to enhance the implant performance. An effective approach to overcoming these challenges involves surface modification using advanced coatings. Therefore, this work provides a comprehensive review of various surface coating materials and techniques employed to enhance the mechanical properties, wear resistance, corrosion resistance, wettability, and biocompatibility of titanium alloys for biomedical applications. This review encompasses an array of coating materials, including metal nitrides (MNs), diamond-like carbon (DLC), high-entropy alloys (HEA), metal oxides (MO), and polymer–metal oxide (P-MO) composites. It offers detailed insights into the operational bio-mechanisms of various coatings, thoroughly discusses how and which type of coatings enhance biocompatibility, and provides valuable insights for advancing the field.

Reducing lattice thermal conductivity (κL) is one of the most effective ways for improving thermoelectric properties. However, the extraction of κL from the total measured thermal conductivity can be misleading if the Lorenz (L) number is not estimated correctly. κL is obtained using the Wiedemann–Franz law, which estimates the electronic part of thermal conductivity κe = L σT, where σ and T are electrical conductivity and temperature, respectively. κL is then estimated as κL = κT − L σT. For metallic systems, the Lorenz number has a universal value of 2.44 × 10 −8 WΩ K−2 (degenerate limit), but for non-degenerate semiconductors, the value can deviate significantly for acoustic phonon scattering, the most common scattering mechanism for thermoelectric materials above room temperature. Up until now, L is estimated by solving a series of equations derived from Boltzmann transport equations. For the single parabolic band (SPB) model, an equation was proposed to estimate L directly from the experimental Seebeck coefficient. However, using the SPB model will lead to an overestimation of L in the case of low bandgap semiconductors, which results in an underestimation of κL, sometimes even negative κL. In this article, we propose a simpler equation to estimate L for a non-parabolic band. The experimental Seebeck coefficient, bandgap (Eg), and temperature (T) are the main inputs to the equation, which nearly eliminates the need for solving multiple Fermi integrals besides giving accurate values of L.

In spatially inverted systems, the complex entanglement of Dzyaloshinskii-Moriya interaction (DMI) and other magnetic anisotropies, mediated by spin-orbit coupling (SOC), influences the emergence and dynamics of the chiral spin textures such as skyrmion. The competing and unified effect of these anisotropies--which is expected to amplify the skyrmionics response in the quantum transport phenomena--is not yet known. Here, we investigate this template and engineer the topological Hall effect (THE) arising from chiral spin texture in a range of La0.7Sr0.3MnO3/CaIrO3 superlattices. The strength of SOC and interfacial DMI are controlled via the architectural design and charge transfer across the interface. All the superlattices display anomalous Hall effect, accompanied by the hump like feature. In (L(3)Iy)(4) (y = 4, 6, and 8) superlattices, the humplike feature that is deemed as the THE is intrinsic in nature and stems from the chiral spin texture. For the intermediate strength of SOC, unique eightfold anisotropic magnetoresistance oscillations manifest owing to the modulation of the magnetic easy axis in the presence of competing anisotropies. For this superlattice, THE shows remarkable enhancement of the order such that it takes complete precedence over anomalous contribution. The thicker superlattice with higher fraction of charge transfer augments ferromagnetic interactions, and the artificial THE appears as a consequence of a dual-channel anomalous Hall effect. This manipulation of the THE is intricately connected to the concurrent presence of magnetic anisotropies, altering the dynamics of chiral spin texture. These findings expand the understanding of the corroborative contributions of competing anisotropies and yield a comprehensive control of chiral properties--a dimension for the utility in next-generation spintronics technologies.

Titanium alloys play a prominent role as metallic biomaterials in the biomedical sector, particularly for implant applications. Various types of Ti alloys are suitable for medical treatment, including Ti6Al4V (Ti64) alloys, which are extensively utilized in biomedical implant materials. This preference was attributed to their commendable strength, excellent corrosion and wear resistance, and satisfactory biocompatibility. Nonetheless, implants produced through diverse additive manufacturing (AM) methods or commercially available methods face performance -related challenges, including mechanical, wear resistance, corrosion resistance, wettability, and biocompatibility. To address these limitations, researchers have actively sought ways to enhance the implant performance. An effective approach to overcoming these challenges involves surface modification using advanced coatings. Therefore, this work provides a comprehensive review of various surface coating materials and techniques employed to enhance the mechanical properties, wear resistance, corrosion resistance, wettability, and biocompatibility of titanium alloys for biomedical applications. This review encompasses an array of coating materials, including metal nitrides (MNs), diamond -like carbon (DLC), high -entropy alloys (HEA), metal oxides (MO), and polymer -metal oxide (P -MO) composites. It offers detailed insights into the operational biomechanisms of various coatings, thoroughly discusses how and which type of coatings enhance biocompatibility, and provides valuable insights for advancing the field.

The choice and engineering of the gate-dielectric (GD) is of paramount importance to the performance and energy-efficiency of two-dimensional (2D) field-effect-transistors (FET) that are considered to be primary candidates for sub-10 nm gate length (L g ) MOSFETs. Despite remarkable progress achieved in recent years by the semiconductor-industry towards realization of high-performance 2D FETs based on transition-metal dichalcogenides (TMDs), achieving fast switching speeds and low device leakage currents remain an open challenge. More specifically, the effect of traps at the dielectric-2D interface and bulk defects in the dielectric on device performance have not been thoroughly investigated. In this paper, taking a common 2D-TMD material (MoS 2 ) as an example, we explore various GDs and dielectric-stacks – their interfaces, traps and defects, by using rigorous ab-initio density-functional-theory (DFT) and non-equilibrium-Green's-function (NEGF) transport. Our framework and analysis provide early insights into the design of n-type 2D MoS 2 FETs, including their gate leakage (I GL ), subthreshold swing (SS), and ON-current (I ON ), and they can be extended to optimize the design and performance of other 2D FETs. More specifically, we demonstrate that monolayer (1L-) and bilayer (2L-) LaOCl/HfO 2 are promising GD stacks to achieve IRDS required values for I GL , SS, and I ON in n-type FETs. Finally, we develop a framework to derive the design-window in terms of material/interface properties for both n-type and p-type 2D FETs and identify potential GD materials as a passivation/seeding layer across different L g for n-type 2D FETs. The results highlight LaOCl as a promising candidate for L g = 7 nm while several materials, including LaOCl and h BN, are viable for L g = 10 nm.

NiPS3 is a van der Waals antiferromagnet which has been shown to exhibit spin-phonon and spin-charge coupling in the antiferromagnetically ordered state below T-N = 155 K. It is also a rare Ni-based negative charge-transfer-type insulator with Ni valence in a linear superposition state psi= alpha d(8)+ beta d(9)L-+ gamma d(10)L(-2), where L- is the ligand hole. Here, we study high-quality single-crystals of Ni1-xZnxPS3 (0 < x < 0.2) using temperature-dependent specific heat and Raman spectroscopy probes. We show that in pristine NiPS3, the phonon mode at 176 cm(-1) (P-2), associated with the vibrations of Ni ions, exhibits a distinct Fano asymmetry. The Fano resonance is particularly pronounced in the paramagnetic phase above T-N, which was further confirmed by temperature dependent Raman data on the Zn-doped crystals. In the Zn-doped crystals, while the magnetism weakens following the mean-field prediction for site-dilution in a honeycomb lattice, the Fano coupling |1/q| strengthens, increasing monotonically with increasing Zn-doping. The x-ray photoemission spectra suggest an increase in the weight of the d(9) and d(10) components in the Zn-doped crystals. These observations indicate the presence of strong electron-phonon coupling in Ni1-xZnxPS3, in addition to the spin-phonon, and spin-charge coupling previously reported.

The low bandgap semiconductor, SnTe is receiving significant attention as a thermoelectric material be-cause of its low toxicity and environment-friendly nature. In this study, we report the effect of co-doping dilute concentrations of Ag and Cu ions in SnTe that suppresses the Sn vacancies leading to optimized thermoelectric properties. Samples of nominal chemical composition Sn1.03-2xAgxCuxTe (x = 0, 0.01, 0.02, 0.04) were prepared by the solid-state route. The Rietveld refinement of powder XRD of these compounds showed a fcc (Fm3 over bar m) structure with no other impurity phases. Diffuse reflectance IR spectroscopy showed an increase in the bandgap upon Ag-Cu co-doping in SnTe, associated with valence band convergence. Electronic band structure calculations confirmed an increase in the bandgap along with a reduction in the energy difference between light and heavy valence bands having maxima at the L and sigma points. Partial density of states (P-DOS) calculations showed that Ag-Cu doping in SnTe does not contribute towards the formation of resonant energy levels. The Seebeck coefficient S of the Sn1.01Ag0.01Cu0.01Te reached a max-imum value of similar to 95 mu V/K at 783 K, compared to 86 mu V/K of pure SnTe. The power factor increased with the doping concentration, reaching similar to 10.8 mu WK-2cm-1 at 783 K for x = 0.04. The lattice thermal conductivity L decreased on Ag-Cu co-doping, with L = 0.44 Wm 1K 1 above 750 K for x = 0.04, which is close to the Cahill model. The combination of higher power factor and reduced lattice thermal conductivity in the Ag-Cu co-doped samples resulted in enhanced ZT = 0.24-0.29 at 773 K.(c) 2023 Elsevier B.V. All rights reserved.