Magnetic topological materials such as Weyl and Dirac magnets exhibit unconventional electronic properties arising from the interplay between magnetic order and band topology, leading to remarkable thermomagnetic and thermoelectric effects. Here, we investigate the ANE in epitaxial thin films of the Weyl ferromagnet candidate Fe5Si3. A pronounced transverse Nernst response exceeding approximately 1.50 microvolt per kelvin is observed at room temperature, together with a giant anomalous Nernst angle of about 0.56, indicating highly efficient conversion between thermal gradients and transverse electric fields. Beyond the anomalous contribution, a sizable topological Nernst signal of approximately 0.43 microvolt per kelvin persists above room temperature, suggesting the possible presence of real-space Berry curvature associated with nontrivial spin textures. First-principles density functional theory calculations combined with symmetry analysis reveal an unconventional electronic structure in which Weyl nodal lines, nodal surfaces, and nearly flat bands coexist near the Fermi level. This rare concurrence of multiple topological band features produces a strongly enhanced and sharply energy-dependent Berry curvature, which governs both the magnitude and temperature evolution of the observed Nernst response. The close quantitative agreement between calculated anomalous Nernst conductivity and experimental results establishes the topological electronic structure as the dominant origin of the observed thermomagnetic transport, highlighting Fe5Si3 as a chemically simple, low-cost binary topological magnet for exploring both real-space and momentum-space Berry-curvature-driven thermoelectric phenomena.

Layered van der Waals (vdW) ferromagnetic materials, such as CrXTeY have attracted enormous attention for their exciting electronic and magnetic properties. In this context, this study reports on the manifestations on the Berry curvature effect induced by systematically altering the structural quality and the thickness of the CrTe2 (CT) thin films. Of note, these CT films are deposited using dc-magnetron sputtering-a scalable and industrially robust technique, which, to the best of our knowledge, has not been employed previously for CrTe2 growth. This distinguishes the film-growth approach adopted in the present work for depositing the CT films from the widely reported molecular beam epitaxy (MBE) and chemical vapor deposition (CVD) routes, which are relatively far less suited for large-scale integration. Two different series of CT films having thickness in 20-60 nm range were deposited on Si(100) substrates at two different optimized growth temperature of 350 degrees C and 400 degrees C, which yielded relatively less crystalline (LC) and highly crystalline (HC) CT films, respectively. Although the Curie temperature (TC) of the LC-and HC-CT films is found to be significantly dependent on their crystalline state, i.e., 140 and 220 K, respectively, a robust perpendicular anisotropy is observed in both the series of CT films (at thickness as high as 20-60 nm), with a high coercivity of 15 and 8 kOe for HC-CT and LC-CT films at 2 K, respectively. Remarkably, the sign of the AHE signal undergoes a change on cooling below 100 K only for the HC-CT films, which is caused by the temperature-dependent change in the Berry curvature. Furthermore, below TC, the longitudinal resistivity of the HC-CT films is predominantly contributed by the electron-magnon scattering contribution as evidenced by its T2 dependence, in sharp contrast to the semiconducting behavior exhibited by the LC-CT films. The sputtered HC-CT films possess superior twodimentional ferromagnetic characteristics, which are comparable to the films grown via chemical vapor deposition and molecular beam epitaxy techniques.

The structural, electronic, and magnetic properties of the different possible interfaces in the (001)-oriented Co2MnAl/MgO and Co2MnAl/GaAs heterostructures are investigated using plane-wave pseudopotential density functional theory. For Co2MnAl/MgO, CoCo-MgMg, CoCo-OO, MnAl-MgMg, and MnAl-OO interfaces in topto-top configurations are studied, while for Co2MnAl/GaAs, both top-to-top (Co-Ga, Co-As, Mn-Ga, Mn-As, Al-Ga, Al-As) and bridge-site (CoCo-Ga, CoCo-As, MnAl-Ga, MnAl-As) interfaces are considered. The outcomes for the structural properties, electronic nature, and magnetization can be categorized based on the atomic termination of the Co2MnAl slab. For both - Co2MnAl/MgO and Co2MnAl/GaAs heterostructures, the interfacial geometries featuring Co- or CoCo-atomic terminations for the Co2MnAl slab exhibit larger adhesion energies (and shorter interfacial bond lengths) compared to those having the Mn-, Al-, or MnAl-atomic terminations of Co2MnAl slab, indicating their greater interfacial stability. Interfaces with the MnAl-, Mn-, or Al-atomic terminations for Co2MnAl slab preserve near half-metallicity, whereas interfaces with Co- and CoCo-terminated Co2MnAl slab display strongly metallic character. All studied interfaces show enhanced magnetic moments relative to their bulk counterparts, primarily arising from interfacial atoms and their nearest neighbors. Regarding magnetic anisotropy, Co2MnAl/MgO heterostructures, across all interfacial morphologies (including all atomic terminations at the interface and geometric arrangement of atoms from both Co2MnAl and X slabs), exhibit small in-plane magnetic anisotropy (IMA). On the other hand, Co2MnAl/GaAs heterostructures exhibit large perpendicular magnetic anisotropy (PMA) of the order of similar to 3-5 MJ/m & sup3; across all interfacial morphologies. Notably, the directional preference (IMA vs PMA) remains invariant to the specific atomic termination of the X-slab. All these findings offer valuable insights for optimizing Co2MnAl-based heterostructures in spintronic applications.

Controlling the interface between W and CoFeB-based buffer or capping layers at an appropriate temperature is essential for modifying the strength of magnetic anisotropy. In this work, we systematically explore the impact of W buffer and capping layers on the structural, topological, and magnetic anisotropy properties of W (5 nm)/CoFeB(10 nm) and CoFeB(10 nm)/W(3 nm) bilayers sputtered at room temperature (RT) and annealed at an optimal annealing temperature (TA) of 400 C. Our findings demonstrate that the bilayer films uniaxial magnetic anisotropy (UMA) with out-of-plane coercivity (Hcp) is highly influenced by the W buffer, capping layers, and TA. Specifically, the Hcp of the CoFeB layer with the buffer and capping layers annealed at 400 C samples exceed several times the coercivity of those unannealed. CoFeB buffered with W and annealed at 400 C shows larger Hcp, two-fold UMA, and higher in-plane UMA energy density (Keff) than the CoFeB/W bilayers, which can be attributed to the W buffer layer inducing the crystallization of CoFeB during annealing. The W buffer, capping layers, and the TA for W and CoFeB-based bilayer samples significantly alter the surface morphology, grain sizes, and surface roughness. The XRD analysis reveals nano-crystallites embedded in the larger grains of the 400 C annealed samples. Hence, this work offers a promising approach to achieving high thermal stability of UMA in W and CoFeB-based spintronic applications.

The interplay between real and reciprocal space topology yields intrinsically linked transport phenomena in magnetic Weyl systems, wherein the broken time-reversal symmetry, strong Dzyaloshinskii-Moriya interaction, and pronounced uniaxial anisotropy stabilize the momentum-space Berry-curvature monopoles (Weyl nodes) and real-space chiral spin textures. We present a combined first-principles and experimental study of epitaxial Fe5Si3 thin films, establishing them as a magnetic Weyl nodal-line material. First-principles Density Functional Theory (DFT) calculations unambiguously reveal that Fe5Si3 hosts a topologically nontrivial electronic structure containing six pairs of Weyl nodes at or near the Fermi level, accompanied by pronounced Berry curvature at high-symmetry points of the Brillouin Zone. High-quality epitaxial films exhibit robust ferromagnetism with a Curie temperature of 370 K and strong magneto crystalline anisotropy. The magneto transport measurements on epitaxial films reveal the corresponding Berry curvature-driven responses, including a significantly large intrinsic anomalous Hall conductivity of 504 S/cm and a high anomalous Hall angle of 5.5

Using the plane-wave pseudopotential method within the framework of density functional theory, Co_2MnAl (100), (110), and (111) surfaces with different atomic terminations have been studied in the context of some key spintronics properties, viz., surface energy, half-metallicity, magnetization, and magnetic anisotropy. The present study reveals that the MnAl-(100), Co-Al-(111), and Al-(111) surfaces exhibit negative surface energies over a wide range of chemical potentials, indicating their strong structural stability. The MnAl-(100), CoCoMnAl-(110), and Co-Mn-(111) surfaces maintain the nearly half-metallic nature like the bulk-Co_2MnAl, while this nearly half-metallic nature even improved for the Al-(111) surface. In contrast, the rest of the considered surfaces, CoCo-(100), Co-Al-(111) and Mn-(111) surfaces, display the strong metallic nature. Magnetization is enhanced for most surface configurations, except for Al-(111), where it decreases due to reduced moments of the exterior atoms. Regarding magnetic anisotropy, only the MnAl-(100) and Co-Mn-(111) surfaces exhibit the positive magneto-crystalline anisotropy of ∼0.23 and ∼0.33 mJ/m2, respectively. All these findings suggest that the Co-Mn-(111) and MnAl-(100) surfaces are quite appealing for spintronics applications, considering the structural stability, electronic properties, and magnetic anisotropy.

Controlling magnetic anisotropy by tailoring interfacial morphology and film structure is essential for optimizing the magnetic properties of nanoscale materials. Magnetocrystalline anisotropy, inherently dictated by crystal symmetry, can be tuned through symmetry-breaking effects. Here we investigate epitaxial Fe4N thin films grown on SrTiO3 (STO) and LaAlO3 (LAO), focusing on substrate-induced morphology and its impact on anisotropy and magnetization reversal. For STO, even a small miscut (alpha approximate to 0.2 degrees) introduces a weak uniaxial magnetic anisotropy (UMA) along step edges, superimposed on the intrinsic biaxial anisotropy (BMA) of Fe4N. In contrast, Fe4N/LAO exhibits a dominant nearly uniaxial anisotropy and complex reversal pathways. The effective anisotropy constant (K-eff) increases from similar to 10(4)J/m(3) on STO to similar to 10(5)J/m(3) on LAO, an order-of-magnitude enhancement. This behavior arises from ferroelastic a-b twin domains in LAO, which impose alternating local strain fields, rotate easy axes, and pin magnetic domain walls. Optical microscopy directly reveals LAO lamellar twins (30-50 mu m) that correlate one-to-one with Fe4N stripe domains observed in Kerr microscopy. Angle-dependent Magneto-Optical Kerr Effect (MOKE) loops confirm multi-step reversal with transformations between charged and uncharged walls. We thus establish a causal pathway: ferroelastic strain -> laterally modulated easy axes -> domain wall pinning -> charged/uncharged wall transformations -> multi-step magnetization reversal. Our findings demonstrate that substrate morphology, rather than lattice mismatch, dictates anisotropy symmetry in Fe4N, positioning Fe4N/LAO as a model platform for room-temperature anisotropy engineering and a promising route toward low-power, reconfigurable spintronic and magnonic devices.

The generation of spin-orbital current is crucial for advancing energy-efficient spintronic devices. Here, the intricate process involved in the generation and conversion of spin and orbital to charge currents in Zr(t = 2, 3, 4.5, 6, 10, 15, 20 nm)/Co60Fe20B20(CFB), Zr/Pt/CFB, and Zr(t)/Pt/CFB/Pt, and Zr/Pt/CFB(t)/Pt heterostructures are investigated using spin-orbital pumping ferromagnetic resonance and longitudinal spin-orbital Seebeck effect measurements. The moderate spin-orbit coupling (SOC) in the CFB layer facilitates the simultaneous generation of spin and orbital currents, which are transferred into adjacent Zr in Zr/CFB and through Pt in Zr/Pt/CFB/Pt layers. Contributions to the spin to charge current or orbital to charge current conversion originating from different physical mechanisms, namely, inverse spin Hall effect (ISHE), inverse orbital Hall effect, and inverse orbital Rashba-Edelstein effect (IOREE) are determined. Notably, introducing a single Pt layer increases the spin-orbital to pure orbital current, in which the charge current conversion via combined effects: ISHE in Pt and IOREE in Zr/Pt interface. In the heterostructure Zr/Pt/CFB/Pt, the effective ISHE contribution is canceled out due to opposite sign of generating ISHE voltage in top and bottom layer of Pt, and only orbital contribution is remaining which arises due to Zr layer. Compared to the value of effective Rashba-Edelstein IORE 0.29 nm for Zr(4.5)/CFB(20) heterostructures, significantly enhanced 500% in values of lambda Zr-eff are observed after Pt-layer insertion at the Zr/CFB interface. The lambda Zr-eff Zr(4.5)/Pt(2)/CFB(20)/Pt(2) heterostructures are 1.78 nm and 1.70 nm, respectively. The results are further substantiated by an alternative experimental technique, i.e., longitudinal spin-orbital Seeback effect measurements. These findings provide new insights into orbital-moment dependent phenomena and offer promising avenues for developing advanced spintronic devices exploiting both spin and orbital degrees of freedom, even in materials having lower SOC.

Using the plane-wave pseudopotential method within the framework of density functional theory, Co2MnAl (100), (110), and (111) surfaces with different atomic terminations have been studied in the context of some key spintronics properties,viz., surface energy, half-metallicity, magnetization, and magnetic anisotropy. The present study reveals that the MnAl-(100), Co-Al-(111), and Al-(111) surfaces exhibit negative surface energies over a wide range of chemical potentials, indicating their strong structural stability. The MnAl-(100), CoCoMnAl-(110), and Co-Mn-(111) surfaces maintain the nearly half-metallic nature like the bulk-Co2MnAl, while this nearly half-metallic nature is even improved for the Al-(111) surface. In contrast, the rest of the considered surfaces -CoCo-(100), Co-Al-(111) and Mn-(111) surfaces-display the strong metallic nature. Magnetization is enhanced for most surface configurations, except for Al-(111), where it decreases due to reduced moments of the exterior atoms. Regarding magnetic anisotropy, only the MnAl-(100) and Co-Mn-(111) surfaces exhibit the positive magneto-crystalline anisotropy of ∼0.23 and ∼0.33 mJ m-2, respectively. All these findings suggest that the Co-Mn-(111) and MnAl-(100) surfaces are quite appealing for spintronics applications while considering the structural stability, electronic properties, and magnetic anisotropy.

We have investigated the magnetic and transport properties of a unique combination of the topological Weyl ferromagnet (FM) Co2MnGa (CMG) and the topological insulator (TI) Bi2Te3 (BT) in order to explore quantum materials and their heterostructures with nontrivial topology in real space as well as momentum space. The thickness- and temperature-dependent properties of this heterostructure are studied in detail. The interfacial perpendicular magnetic anisotropy is observed in Co2MnGa at a thickness as high as 3 nm. The thickness-dependent tuning of the Fermi level leads to distinct transport characteristics in CMG(t)/BT heterostructures. The study also reports two unconventional observations in the Hall effect, i.e., the sign reversal of the anomalous Hall effect and the emergence of the topological Hall effect, both of which exhibit a significant dependence on temperature. The topological Hall effect, characterized by a high squareness ratio and a large Hall resistivity value of similar to 189 nQ cm at 5 K, is observed in a wide temperature range below Tc in the CMG(7 nm)/BT(10 nm) heterostructure. This effect can be attributed to the presence of chiral magnetic textures induced by the interfacial DzyaloshinskiiMoriya interaction, arising from the strong spin-orbit coupling (SOC) of BT. This conclusion is supported by the absence of such unconventional signatures in transport and magnetic measurements in another similar series CMG(t)/W(10 nm). Therefore, the interplay of strong intrinsic Berry curvature in CMG (as deduced from scaling mechanisms) and the high SOC of BT enable the FM/TI combination to host unconventional spin textures, which may provide an important building block for the next generation of spintronic devices.

Mn2Sb, a ferrimagnet exhibiting spin reorientation transitions (SRT), provides a promising platform to explore spin-dependent transport phenomena relevant for spintronics. Here, we systematically investigate the structural, magnetic, and transport properties of Mn2Sb thin films grown by co-magnetron sputtering. Structural analysis shows that substrate temperature strongly influences crystallite orientation and grain growth. Microstrain (epsilon approximate to 0.155 %), identified through Williamson-Hall analysis, together with a modest change in tetragonality, influences both the magnetic and transport properties. Magnetization measurements confirm a ferrimagnetic phase with out-of-plane orientation (FI-I) above similar to 240 K, which rotates to an in-plane state (FI-II) below this temperature via SRT. Unlike bulk Mn2Sb, which remains FI-II to the lowest temperatures, the thin films exhibit coexistence of FI-II and antiferromagnetic (AF)-like regions below similar to 120 K. This mixed magnetic state is further supported by the observation of spontaneous exchange bias, likely stabilized by enhanced tetragonality (deviated a/c ratio) and microstrain in the films. Transport measurements consistently follow these magnetic regimes. The resistivity shows metallic behavior with a T-3/5 dependence above 150 K (spin fluctuations) and a T-1.6 law below 100 K (electron-magnon scattering). The anomalous Hall resistivity ((rho(A)(xy))exhibits a clear kink at the SRT and a broad maximum near 200 K, where the in-plane FI-II configuration becomes dominant, reflecting enhanced asymmetric spin-orbit scattering during reorientation. Magnetoresistance remains negative across all temperatures, with a maximum (similar to 3 %) near 100 K in the FI-AF coexistence regime. These findings show that microstrain and lattice distortion govern the magnetic-transport coupling in Mn2Sb thin films. Introduction

In this study, we achieved the improvement of uniaxial perpendicular magnetic anisotropy (PMA) in the W/MgAl2O4/CoFeMnSi/W/CoFeMnSi/MgAl2O4/W heterostructure by manipulating the annealing temperature (TA) [350 C, 450 C, and 550 C]. We observed a maximum effective PMA energy density (Keff) of = 1.604 x 106 erg/cc with low saturation magnetization (Ms) at the specified TA. The enhancement of Keff with Ms is significantly influenced by structural variations at the interfaces of CoFeMnSi and MgAl2O4, attributed to sufficient interfacial oxidation dependent on the TA. The TA was identified as a critical factor affecting the surface morphology, grain size, and surface roughness of the multilayer. Fourier-transform infrared (FT-IR) measurements were employed to confirm the presence of Co-O or Fe-O bond in the multilayer structures, elucidating the true origin of PMA. The control of interfacial oxidation at the interface during annealing is crucial for regulating the strength of PMA. Therefore, this double CoFeMnSi/MgAl2O4-based multilayer presents a promising avenue, serving as a favorable candidate for future p-MTJs-based spintronic devices with enhanced thermal stability.

Two-dimensional transition metal dichalcogenides (TMDs) have drawn immense interest due to their strong spin-orbit coupling and unique layer number dependence in response to spin-valley coupling. This leads to the possibility of controlling the spin degree of freedom of the ferromagnet (FM) in thin film heterostructures and may prove to be of interest for next-generation spin-based devices. Here, we experimentally demonstrate the odd-even layer dependence of WS2 nanolayers by measurements of the ultrafast magnetization dynamics in WS2/Co3FeB thin film heterostructures by using time-resolved Kerr magnetometry. The fluence (photon energy per unit area) dependent magnetic damping (alpha) reveals the existence of broken symmetry and the dominance of inter- and intraband scattering for odd and even layers of WS2, respectively. The higher demagnetization time, tau m, in 3 and 5 layers of WS2 is indicative of the interaction between spin-orbit and spin-valley coupling due to the broken symmetry. The lower tau m in even layers as compared to the bare FM layer suggests the presence of a spin transport. By correlating tau m and alpha, we pinpointed the dominant mechanisms of ultrafast demagnetization. The mechanism changes from spin transport to spin-flip scattering for even layers of WS2 with increasing fluence. A fundamental understanding of the two-dimensional material and its odd-even layer dependence at ultrashort timescales provides valuable information for designing next-generation spin-based devices. Odd-even WS2 layer number dependent ultrafast demagnetization and damping are studied by varying the pump fluence.

Spin gapless semiconductors (SGSs), novel quantum materials, are notable for their tunable spin-transport properties. Considering that the SGS materials might have an invariably deformed lattice upon integration into devices, and given that the SGS nature is highly sensitive to external factors, the impact of lattice distortions on the different physical properties of CoFeCrGa SGS alloy has been investigated using density functional theory calculations. For lattice distortions, the uniform strain corresponding to -6%≤ ΔV / V_0 ≤ 6% (a: 5.60-5.83 ), and the tetragonal distortion corresponding to 0.8 ≤ c/a ≤ 1.2 (a: 5.38-6.16 , c: 4.92-6.45 ) are modelled. All uniformly strained CoFeCrGa structures are found to display SGS character, magnetic isotropy, small anomalous Hall conductivity (AHC), and small spin Hall conductivity (SHC) - closely resembling those of the ideal CoFeCrGa structure. In contrast, the tetragonally deformed structures display nearly half-metallic behavior with very high spin polarization, very large magnetic anisotropy (∼ 10^6 J/m^3), and very large AHC ranging from (-215 to 250 S/cm) depending on the axial ratio of the distorted structure. The SHC, however, does not change significantly under tetragonal distortion and remains nearly of the same order as that of the Y-I ordered structure. In summary, these findings demonstrate that CoFeCrGa displays favorable spintronic properties even under lattice distortions, underscoring its potential for next-generation spintronic applications.

This study investigates the influence of swift heavy ion irradiation on exchange anisotropy (H-EA) and coercivity (H-C) in a set of top-pinned SiOx/Cu/Ni81Fe19/Ir7Mn93/Ta bilayers fabricated by ion beam sputtering at room temperature (RT) in presence of an in-plane in situ static field of 1 kOe. Subsequently, the bilayers were subjected to a magnetic annealing process at 300 degrees C for an hour in the presence of a 3.5 kOe magnetic field. By systematically increasing the Au ion fluences from pristine to 3.3 x 10(11) ion/cm(2), the positive exchange anisotropy (PEA) and negative exchange anisotropy (NEA) were found to be enhanced by 10 Oe and similar to 178 Oe, respectively. However, once the ion fluences surpassed the necessary threshold of 3.3 x 10(11) ion/cm(2) required for defect creation/pinning centers in the antiferromagnetic (AF) layer, a reduction in both H-EA and H-C was observed due to the interfacial mixing. The enhancement in PEA and NEA is attributed to the creation of defects or hyperthermal heating in the AF layer as a consequence of ion irradiation. These experimental results align with the framework of the diluted antiferromagnetic model. The persistent training effect, which is observed even after irradiation, confirms the existence of a highly metastable interface between the NiFe/IrMn layer. Thus, ion irradiation emerges as a powerful tool for precisely tailoring the H-EA and H-C of the bilayers by systematically controlling the ion fluence.

Owing to the robust spin-polarized topological conducting surface states, topological insulators (TIs) offer huge promise of establishing ultrafast operation and low power consumption in spin-based applications like quantum communication and magnetic memory devices. In this paper, high spin-to-charge conversion (SCC) is evidenced at room temperature in the TI/ferromagnet (FM) interface engineered Al2O3(0001)/Sb2Te3 2 O 3 (0001)/Sb 2 Te 3 (10 nm)/Ru(0-12 nm)/Co60Fe20B20(20 60 Fe 20 B 20 (20 nm)/Ru (4 nm) heterostructure system (with Sb2Te3 2 Te 3 as TI and Co 60 Fe 20 B 20 as FM) grown via DC magnetron cosputtering. The generation of a significantly high charge current density is observed for a particular Ru interlayer (IL) thickness of 4 nm, above which the SCC efficiency of these heterostructures is shown to be inversely governed with the increase in the thickness of the Ru IL. The SCC efficiency in these heterostructure is quantitatively estimated through inverse spin Hall effect (ISHE) measurements, where ' 500% enhancement in the SCC is witnessed corresponding to insertion of a 4-nm-thin Ru IL. The inverse Edelstein effect length ( lambda IEE ) for the heterostructure with the largest SCC is determined to be ' 0.19 +/- 0.01 nm, which is comparable with the reported values of other TIs/FM heterostructures. Longitudinal spin Seebeck effect (LSSE) measurements, which corroborate the ISHE findings, also demonstrated the significant power-generation potential in these heterostructures. When the heterostructure is considered as a parallel load resistance model, the analysis of LSSE results disentangles the pure SSE contribution of Sb2Te3 2 Te 3 from the anomalous Nernst effect contribution of the Co 60 Fe 20 B 20 FM. Similar trends are confirmed in other test heterostructures fabricated, wherein either the TI Sb2Te3 2 Te 3 layer is replaced with other chalcogenide TI Bi2Te3, 2 Te 3 , or the Ru HM layer is replaced with Nb, thereby confirming the generalization of the approach of controlling the SCC efficiency. These results highlight the potential of TIs and interface engineering for the realization of ultralow power devices and high-current spin Seebeck thermoelectric devices for future spin-based technologies and quantum communication.