Magnetic Spin Research Articles

Unusual Anomalous Hall Effect in Two-Dimensional Ferromagnetic Cr7Te8

Two-dimensional (2D) materials with inherent magnetism have attracted considerable attention in the fields of spintronics and condensed matter physics. The anomalous Hall effect (AHE) offers a theoretical foundation for understanding the origins of 2D ferromagnetism (2D-FM) and offers a valuable opportunity for applications in topological electronics. Here, we present uniform and large-size 2D Cr7Te8 nanosheets with varying thicknesses grown using the chemical vapor deposition (CVD) method. The 2D Cr7Te8 nanosheets with robust perpendicular magnetic anisotropy, even a few layers deep, exhibit a Curie temperature (TC) ranging from 180 to 270 K according to the varying thickness of Cr7Te8. Moreover, we observed a temperature-induced reversal in the sign of the anomalous Hall resistance, correlating with changes in the intrinsic Berry curvature. Additionally, the topological Hall effect (THE) observed at low temperatures suggests the presence of non-trivial spin chirality. Our findings about topologically non-trivial magnetic spin states in 2D ferromagnets provide a promising opportunity for new designs in magnetic memory spintronics.

Spin and orbital magnetic moments of UTe2 induced by the external magnetic field

Correlated band theory implemented as a combination of the relativistic density functional theory with exact diagonalization [DFT+U(ED)] of the Anderson impurity term with Coulomb repulsion U in the 5f shell is applied to the magnetic field polarized state of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {UTe}_2$$\\end{document}. We demonstrate that the DFT+U(ED) approach provides a good agreement with very recent x-ray absorbtion near edge structure (XANES) and x-ray magnetic circular dichroism (XMCD) experiments. The branching ratio for the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$M_{4,5}$$\\end{document} edge transitions of uranium, and the valence spin-orbit interaction per hole were evaluated in a perfect agreement with the XANES. The orbital-to-spin moment ratio is calculated with DFT+U(ED) within the range of values extracted from XMCD data. The uranium atom 5f-shell ground state with 33 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f^2$$\\end{document} and 58 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f^3$$\\end{document} configurations is determined. Both XMCD and DFT+U(ED) point out the intermediate valence of uranium as well as itinerant-localized dichotomy in \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {UTe}_2$$\\end{document}.

Enhancement of Single-Molecule Magnet Properties by Manipulating Intramolecular Dipolar Interactions.

A new single-molecule magnet (SMM) complex [K(18-crown-6)][(COT)Er(µ-Cl)3Er(COT)] (Er2Cl3, COT=cyclooctatetraenide dianion) is obtained by the reaction of [(COT)Er(µ-Cl)(THF)]2 (Er2Cl2, THF=tetrahydrofuran) with an equivalent of KCl in the presence of 18-crown-6. The two COT-Er units in the newly formed complex are triply bridged by µ-Cl ligands, leading to the "head-to-tail" alignment of the magnetic easy axes distinctly different from the "staggered" arrangement in the precursor complex. This structural transformation has led to significantly enhanced intramolecular dipolar interactions and a reduced transverse component of the crystal fields, increasing the energy barrier from 150(8) K for Er2Cl2 to 264(4) K for Er2Cl3 and extending its magnetic relaxation time at 2 K by 2500 times with respect to Er2Cl2. More importantly, the blocking temperature increased from lower than 2 K for Er2Cl2 to 8 K for Er2Cl3, and the magnetic hysteresis loops at 2 K changed from butterfly-shaped for Er2Cl2 to open hysteresis loop with coercive force of 7 kOe for Er2Cl3. These results suggest that the properties of SMMs can be effectively tuned and improved by rationally arranging magnetic spins via molecular engineering.

Role of voltage-controlled magnetic anisotropy in the recent development of magnonics and spintronics

With significant recent progress in the thin film deposition and nanofabrication technology, a number of physical phenomena occur at the interfaces of magnetic thin films, and their heterostructures have been discovered. Consequently, the electric field-induced modulation of those interfacial properties mediated through spin–orbit coupling promises to develop magnetic material based smarter, faster, miniaturized, energy efficient spintronic devices. Among them, the electric field-induced modification of interfacial magnetic anisotropy, popularly termed as voltage-controlled magnetic anisotropy (VCMA), has attracted special attention because of its salient features. This article is devoted to reviewing the recent development of magnonics, which deals with collective precessional motion of ordered magnetic spins, i.e., spin waves (SWs), and skyrmions with chiral spin textures, with VCMA, including the perspectives of this research field. Starting with a broad introduction, the key features of VCMA and its advantages over other electric field-induced methods are highlighted. These are followed by describing the state-of-the-art of VCMA, and various other direct and indirect electric field-induced methods for magnetization reversal; controlling skyrmion dynamics; excitation, manipulation, and channeling of SWs; and tailoring magnonic bands. The critical challenges, their possible solutions, and future perspectives of this field are thoroughly discussed throughout the article.

Live magnetic observation of parahydrogen hyperpolarization dynamics

Hyperpolarized nuclear spins in molecules exhibit high magnetization that is unachievable by classical polarization techniques, making them widely used as sensors in physics, chemistry, and medicine. The state of a hyperpolarized material, however, is typically only studied indirectly and with partial destruction of magnetization, due to the nature of conventional detection by resonant-pickup NMR spectroscopy or imaging. Here, we establish atomic magnetometers with sub-pT sensitivity as an alternative modality to detect in real time the complex dynamics of hyperpolarized materials without disturbing or interrupting the magnetogenesis process. As an example of dynamics that are impossible to detect in real time by conventional means, we examine parahydrogen-induced 1H and 13C magnetization during adiabatic eigenbasis transformations at [Formula: see text]T-field avoided crossings. Continuous but nondestructive magnetometry reveals previously unseen spin dynamics, fidelity limits, and magnetization backaction effects. As a second example, we apply magnetometry to observe the chemical-exchange-driven 13C hyperpolarization of [1-13C]-pyruvate-the most important spin tracer for clinical metabolic imaging. The approach can be readily combined with other high-sensitivity magnetometers and is applicable to a broader range of general observation scenarios involving production, transport, and systems interaction of hyperpolarized compounds.

Manipulation of d-Orbital Electron Configurations in Nonplanar Fe-Based Electrocatalysts for Efficient Oxygen Reduction.

Manipulation of the spin state holds great promise to improve the electrochemical activity of transition metal-based catalysts. However, the underlying relationship between the nonplanar metal coordination environment and spin states remains to be explored. Herein, we report the precise regulation of nonplanar Fe atomic d-orbital energy level into an irregular tetrahedral crystal field configuration by introducing P atoms. With the increase of P coordination number, the spin magnetic moment decreases linearly from 3.8 μB to 0.2 μB, and the high spin content decreases linearly from 31% to 5%. Significantly, a volcanic curve between the spin states of Fe-based catalysts (Fe-NxPy) and oxygen reduction reaction (ORR) activity has been unequivocally established based on the thermodynamic results. Thus, the Fe-N3P1 catalyst with a 19% medium spin state experimentally exhibits the optimal reaction activity with a high half-wave potential of 0.92 V. These findings indicate that regulating electron spin moments through coordination engineering is a promising catalyst design strategy, providing important insights into spin catalysis.

Spin-Polarized Antiferromagnetic Metals

Spin-polarized antiferromagnets have recently gained significant interest because they combine the advantages of both ferromagnets (spin polarization) and antiferromagnets (absence of net magnetization) for spintronics applications. In particular, spin-polarized antiferromagnetic metals can be useful as active spintronics materials because of their high electrical and thermal conductivities and their ability to host strong interactions between charge transport and magnetic spin textures. We review spin and charge transport phenomena in spin-polarized antiferromagnetic metals in which the interplay of metallic conductivity and spin-split bands offers novel practical applications and new fundamental insights into antiferromagnetism. We focus on three types of antiferromagnets: canted antiferromagnets, noncollinear antiferromagnets, and collinear altermagnets. We also discuss how the investigation of spin-polarized antiferromagnetic metals can open doors to future research directions.

Mn doping-induced twofold spin reorientation and multi-step spin switching in NdFeO3 single crystal

Magnetization reversal and magnetic state regulation are the basis of application for magnetic materials in information processing. Here, twofold spin reorientation transitions (SRT) and field-induced multi-step spin switching phenomena were observed in NdMn0.2Fe0.8O3 (NMFO) single crystals grown via the optical floating zone method. Magnetic anisotropy was systematically investigated in both Zero-Field-Cooled (ZFC) and Field-Cooled (FC) modes. The NMFO single crystal exhibited twofold SRTs: from Γ4 (Gx, Ay, Fz) to Γ1 (Ax, Gy, Cz) and from Γ1 (Ax, Gy, Cz) to Γ2 (Fx, Cy, Gz). Furthermore, a magnetic field-induced spin reorientation transition was identified along the c-axis. Additionally, closer proximity to the SRT temperature corresponded to a reduced magnetic field requirement for inducing the spin reorientation transition. These findings contribute to our comprehension of spin dynamics in NMFO, presenting possibilities for future device applications.

Band gap correction via GGA[formula omitted]mBJ function and strained modulated physical properties of 2D-like DyOBr oxybromide

Two-dimensional (2D) oxyhalides offer unique and fascinating properties due to long-range magnetic ordering in a low dimensional limit. These have potential applications in spintronics and low-dimensional data storage devices. Herein, we demonstrate the biaxial ([110]) strain impact on the electronic and magnetic properties of thermodynamically stable 2D like DyOBr oxybromide based on the first-principles calculations including Hubbard parameter (U) and U+mBJ (modified-Becke-Johnson) methods as well as spin–orbit coupling (SOC) effects. Our calculations predict that an unstrained system exhibits an anti-ferromagnetic (AFM) insulating state with a direct wide energy band gap (Eg) of 5.404 eV within GGA+U+mBJ scheme and the estimated Neel temperature (TN) using the Ising model is 13 K, which is in excellent agreement with the experimentally observed values of 5.41 eV and 9.5 K, respectively. Moreover, it is revealed that Dy ions displayed a large partial spin magnetic moment (ms) of 4.969 μB/f.u. (per formula unit) with S = 2.5 as they lie in ＋ 3 state having the electronic configuration of [fx(x2−3y2)+fy(3x2−y2)]↑2↓1, [fxz2+fyz2]↑2↓1, [fz(x2−y2)]↑1↓0, [fxyz]↑1↓0, and [fz3]↑1↓0. Interestingly, the system displays a large magnetic anisotropy energy of 4.31 meV/atom with a magnetic easy axis of [100] (a-axis), which enhances its utilization in magnetic memory devices. Further, it is established that the AFM insulating behavior of the structure remains robust against biaxial ([110]) strain for the considered range of ±5%. However, a well-ordered shift in conduction band edge (CBE) position to higher and lower energy values is predicted for compressive and tensile strains, respectively. Strikingly, it is found that the TN increases to 265% for ＋5% strain.

Ab Initio Study of the Influence of Spin and Orbital Magnetic Moments on the Stability of Magnetic and Charge Distribution in Co:ZnO Monolayer.

The development of ultrathin magnets with tunable magnetic properties is essential for advancing quantum computing technologies. In this study, density functional theory (DFT) calculations were employed to investigate the atomic and electronic structures of a ZnO monolayer embedded with cobalt atoms. The impact of spin dynamics on charge transfer within the Co:ZnO system was thoroughly examined. Results revealed that the orbital magnetic moment of the cobalt atoms plays a crucial role in stabilizing the magnetic and charge distributions across the system. These findings offer valuable insights for the design and fabrication of quantum devices, thereby highlighting the potential of Co-doped ZnO monolayers in quantum computing applications.

Exact results of the one-dimensional repulsive Hubbard model

We present analytical results of the fundamental properties of the one-dimensional (1D) Hubbard model with a repulsive interaction. The new model results with arbitrary external fields include: (I) using the exact solutions of the Bethe ansatz equations of the Hubbard model, we first rigorously calculate the gapless spin and charge excitations, exhibiting exotic features of fractionalized spinons and holons. We then investigate the gapped excitations in terms of the spin string and thek-Λstring bound states at arbitrary driving fields, showing subtle differences in spin magnons and chargeη-pair excitations. (II) For a high-density and high spin magnetization region, i.e. near the quadruple critical point, we further analytically obtain the thermodynamic properties, dimensionless ratios and scaling functions near quantum phase transitions. (III) Importantly, we give the general scaling functions at quantum criticality for arbitrary filling and interaction strength. These can directly apply to other integrable models. (IV) Based on the fractional excitations and the scaling laws, the spin-incoherent Luttinger liquid (SILL) with only the charge propagation mode is elucidated by the asymptotic of the two-point correlation functions with the help of conformal field theory. We also, for the first time, obtain the analytical results of the thermodynamics for the SILL. (V) Finally, to capture deeper insights into the Mott insulator and interaction-driven criticality, we further study the double occupancy and propose its associated contact and contact susceptibilities, through which an adiabatic cooling scheme based upon quantum criticality is proposed. In this scenario, we build up general relations among arbitrary external- and internal-potential-driven quantum phase transitions, providing a comprehensive understanding of quantum criticality. Our methods offer rich perspectives of quantum integrability and offer promising guidance for future experiments with interacting electrons and ultracold atoms, both with and without a lattice.

Microwave artificial neurons based on magnetic tunnel junction nano-oscillators for image recognition and denoising

We report a microwave artificial neuron based on magnetic tunnel junction spin torque nano-oscillator (STNO). Based on STNO neurons, the three-layer full connected artificial neural network (ANN) are constructed to recognize handwritten digit with a produced accuracy of up to 90.95%. To address noise inherent in real circuits leads to poor recognition accuracy, we harness the frequency mutation characteristics of the STNO output near the critical threshold current for denoising handwritten digits corrupted by noise. Before and after denoising using the aforementioned ANN, the recognition accuracy is improved from 55.98% to 88.76%.

Pioneering computational insights into the structural, magnetic, and thermoelectric properties of A3XN (A=Co, Fe; X=Cu, Zn) anti-perovskites for advanced material applications

This study pioneers the utilization of computer-controlled simulations to elucidate the structural, elastic, electronic, and thermoelectric properties of A3XN anti-perovskites (A = Co, Fe; X = Cu, Zn). Starting with the development of a detailed structural model, structural optimization calculations identify the stable Pm-3m cubic phase, aligning with experimental findings. Also, these optimizations indicate the ferromagnetic phase stability of A3XN anti-perovskites, further supported by positive Curie-Weiss constants of 60 K, 80 K, and 100 K for Co₃CuN, Co₃ZnN, and Fe₃CuN, respectively. The spin-dependent electronic properties, including band structure and density of states, are explored using multiple exchange-correlation (XC) functionals—GGA, GGA + U, and GGA + mBJ. The results uphold the metallic nature of the materials, accompanied by significant spin magnetic moments. Specifically, the calculated values of magnetic moments for Co3CuN, Co3ZnN, and Fe3CuN are 5.08 μB, 3.70 μB, and 7.61 μB, respectively. Furthermore, we compute the Curie temperatures for each compound, 942.48 K for Co3CuN, 692.7 K for Co3ZnN, and 1400.41 K for Fe3CuN, which are substantially elevated, indicating robust ferromagnetic behavior that persists well above ambient conditions. Mechanical properties, including stability, deformation behavior, and ductility, are validated through elastic calculations, with various mechanical anisotropy factors examined. From an application perspective, the thermoelectric characteristics of Co3CuN, Co3ZnN, and Fe3CuN are meticulously evaluated, focusing on parameters like the Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and figure of merit (zT). The analysis highlights promising power factor values of 3.0×1011(W/cm.K2), 4.0×1011(W/cm.K2), and 6.0×1011(W/cm.K2) for Co3CuN, Co3ZnN, and Fe3CuN, respectively, suggesting potential for enhanced efficiency in thermopower generation, particularly in waste heat recovery applications. Furthermore, the study provides a comprehensive analysis of the ground-state optical properties of A3XN, including the dielectric constant, photoconductivity, reflectivity, refractive index, absorption coefficient, and extinction coefficient. The reflectivity spectra demonstrate high reflectivity of 45 % across visible and ultravioletregions, suggesting suitability for applications in coatings designed to mitigate solar heating effects.

Manifestation of edge spin magnetization in normal metal

In paramagnetic metal (Al), the nonlinear behavior of the spin component in the Hall effect was discovered, indicating the role of edge transverse spin magnetization. It is shown how its manifestation is related to the spin precession period and their relaxation length, which weakly depend on the momentum relaxation time.

AC loss and shielding in stacks of coated conductors: Analytic modelling and comparison to experiment

This work explores the effects of the stacking of coated conductor tapes on their AC loss and penetration fields (Bp). The penetration field Bp and AC loss of short lengths of coated conducted tape stacks are analyzed, measured, and compared to a simple analytic model. The tape widths (w) and number of tapes in the stacks (Ns) were 4 mm (Ns = 1,3,5, series-305) and 12 mm (Ns = 1–40, series-244). Experimentally, the losses of the series-244 and series-305 tape stacks were measured in a spinning magnet calorimeter (SMC) in which the samples are exposed to a spinning field of frequency, f, up to 110 Hz and amplitude B0 = 566 mT and the power is measured by a calibrated boil-off calorimeter. These results were compared to calculated loss as a function of Ns for both tapes. In addition, the calculated Bp was plotted vs Ns. The basic effect observed was that stacking coated conductor tapes tended to form an effective composite with an increase Bp,comp and modified loss (For B0 < Bp,comp, Ptot was reduced with Ns, the effect saturating for Ns > 20). This could be understood in terms of treating a stack of conductors as a composite described in terms of a Brandt equations applied to a dilute superconductor. The results show and model the significantly reduced loss that stacks of conductors can have significantly for moderate levels of applied field. Such results are directly transferrable to cables of stacked strands.

Magnetic properties and helical spin structure of another compound Ca3SbFe3Si2O14 from the family of iron-containing langasites

A strong interest is attracted to the langasite-type compounds containing magnetic 3d ions. Coexistence of electric and magnetic order parameters in such materials can provide a new variety of multiferroics. In our work, another Fe-based langasite with a nearly stoichiometric composition Ca3SbFe3Si2O14 was synthesized. X-ray diffraction and X-ray fluorescence analyses, studies of magnetic susceptibility, specific heat and Mössbauer spectroscopy were performed. The crystal structure of Ca3SbFe3Si2O14 (CSFS) was found to be hexagonal, space group P321. From full-profile analysis by the Le Bail method, the lattice parameters a = 8.115(1) Å, c = 5.058(1) Å, V = 288.4(1) Å3 were determined. The temperature dependence of magnetic susceptibility χ(Т) indicates the formation of long-range magnetic order at temperatures below TN = 34 K. The negative value of Weiss temperature θCW indicates the domination of antiferromagnetic exchange interaction. From the value of the Curie constant, the effective magnetic moment per Fe3+ ion µeff = 6.12 µB was estimated, which is slightly higher than the expected value 5.9 µB for the 3d5 - S = 5/2 state of iron. Measurements of the specific heat allowed a Debye temperature value ΘD = 390(10) K to be obtained. Based on the assessment of the magnetic contribution to the specific heat, the value of magnetic entropy ΔSmag ∼ 47.8 ± 5.6 J/mol K was determined. Hyperfine interaction parameters obtained from Mössbauer spectra indicate a helical magnetic ordering of iron moments in langasite Ca3SbFe3Si2O14. The period of a magnetic helicoid is about five periods of the crystal structure along the c axis. The calculated value of the angle (α) between the main axis of the electric field gradient Z′ at iron nuclei and the crystallographic c axis (67.2°) is significantly greater than in other langasites Ba3SbFe3Si2O14 (28.8°), Ba3NbFe3Si2O14 (36°), Ba3TaFe3Si2O14 (34.8°). This may be due to the more contracted FeO4 tetrahedra in CSFS compared to those in the other compositions.

Excellent Barocaloric Effect by Modulating Geometrical Frustrations in Mn3Pt.

Barocaloric materials hold great promise for next-generation solid-state cooling devices because of their green and efficient cooling performance. The insights into low-pressure-driven barocaloric materials are expected to pave the way for the widespread application of barocaloric refrigeration technology. Here, we reveal the low-pressure-driven large barocaloric effect (BCE) modulated by geometrical frustrations in Mn3Pt. The highest sensitivity to pressure of Mn3Pt in metal BCE materials results in an excellent temperature-change strength of 9.77 K 100-1 MPa-1. Neutron powder diffraction and first-principles calculations point out the dual effect of geometrical frustration on modulating the unusual BCE, which not only induces giant volume expansion by inspiring strong spin fluctuation and magnetic moment but also enhances the sensitivity of magnetic phase transition. The model of the dual effect of geometrical frustration in magnets with geometrical frustration is established, which will promote the research progress of barocaloric refrigeration devices.

Electronic structures, elastic behaviors and magnetic properties of monolayer [formula omitted] and [formula omitted] Ni[formula omitted]I[formula omitted]

This study investigates the electronic structures, elastic behaviors, and magnetic properties of monolayer Ni2I2 in two novel phases, P3̄m1 and P4/nmm, using first-principles calculations and Monte Carlo simulations. The electronic structures of P3̄m1 and P4/nmm phases show half-metallic properties with spin magnetic moments of 0.85 and 0.82 μB respectively. Both phases exhibit mechanical and dynamic stability. The P3̄m1 phase has isotropic elastic properties and good ductility, while the P4/nmm phase shows significant crystallographic anisotropy. The spin exchange coupling constants between the nearest and the next-nearest neighbor Ni ions in the P4/nmm phase are nearly an order of magnitude higher than those in the P3̄m1 phase, with the former having a Curie temperature close to room temperature at 296 K, significantly higher than the 27 K of the latter. The strain modulation range for structural and magnetic phase transitions between the P3̄m1 and P4/nmm phases is provided theoretically.

PT Symmetry Breaking Induced Anomalous Valley Hall Effect in 2D Antiferromagnetic Semiconductor.

Realizing the anomalous valley Hall (AVH) effect in two-dimensional (2D) materials is of crucial importance for information processing and recording technology. While the research in this field mainly focuses on ferromagnetic systems, little is known about antiferromagnetic systems. Here, using k·p model analysis, we report a novel mechanism of realizing the AVH effect in 2D antiferromagnetic materials. This physics is related to the PT symmetry breaking induced by intrinsic staggered sublattice potential, which is introduced by asymmetric magnetic ions located at different sublattices. With reversal of the magnetic orientation on different sublattices, the AVH effect can be reversed. Based on first-principles calculations, we further demonstrate this mechanism in an antiferromagnetic monolayer of NiRuCl6. Intriguingly, due to the d orbital mismatch near the Fermi level, monolayer NiRuCl6 simultaneously owns zero net magnetization and large spin splitting and valley polarizations, which facilitates the observation of the AVH effect. Our findings greatly enrich the research on valley physics in antiferromagnetic systems.

Alkali-based half metals as sustainable materials for spin electronics and energy harvesting application — Materials computation

The structural, mechanical, electronic, magnetic, and thermoelectric properties of alkali-based half-Heusler alloys (LiCrGe, LiCrSn, and LiCrPb) are investigated using the Wien2k code. These alloys exhibit half-metallic behavior in both ferromagnetic and antiferromagnetic phases. A phase transition from a stable ferromagnetic phase to a more stable antiferromagnetic phase indicates ductility. In the antiferromagnetic phase, using GGA exchange–correlation functional with 10,000 K-points, a band gap is observed in the spin-up state, with band gap energies of 0.9367 eV, 0.7762 eV, and 0.7913 eV, respectively. The alloys have a spin magnetic moment of −3μB, consistent with the Slater–Pauling rule. They also exhibit high Curie temperatures and 100% spin polarization in the spin-down state. The alloys LiCrZ (Z = Ge, Sn, Pb) shows promising thermoelectric behavior. Using the BolzTrap package, we observed, high Seebeck coefficient, electrical conductivity, low thermal conductivity, and enhanced power factor. The p-type LiCrZ (Z = Ge, Sn, Pb) compounds show thermoelectric figure of merit of 0.52, 0.76, and 0.84 at 1200 K, while n-type compounds have figure of merit of 0.56, 0.65, and 0.80 at the same temperature. These properties make these materials promising for spintronic and thermoelectric applications.