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Delocalized electron and phonon structures are directives for rationally tuning the intrinsic physicochemical properties of 2D materials by redistributing electronic density. However, it is still challenging to accurately manipulate the delocalized electron and systematically study the relationships between physiochemical properties and practical nanodevices. Herein, the effects of delocalized electrons engineering on blue‐arsenic‐phosphorus (β‐AsP)‐based practical devices are systematically investigated via implementing vacancies or heteroatom doping. A tendency of carrier conductivity property from "half‐metal" to "metal" is initially found when tuning the electronic structure of β‐AsP with adjustable vacancy concentrations below 2 at% or above 3 at%, which can be ascribed to the introduction of delocalized electrons that cause asymmetric contributions to the electronic states near the implementation site. In optical logic device simulations, broadband response, triangular wave circuit system signal, and reverse polarization anisotropy are achieved by adjusting the vacancy concentration, while extinction ratios are as high as 1561. The electric and thermic‐logic devices realize the highest available reported giant magnetoresistance (MR) up to 1013% and 1039% at vacancy concentrations of 1.67% and 0.89%, respectively, which is significantly superior to the reports. The results shed light on the electronic delocalization strategy of regulating internal structures to achieve highly efficient nanodevices. [ABSTRACT FROM AUTHOR]

The interplay between charges and spins may influence the dynamics of the carriers and determine their thermoelectric properties. In that respect, magneto-thermoelectric power MTEP, i.e. the measurements of the Seebeck coefficient S under the application of an external magnetic field, is a powerful technique to reveal the role of magnetic moments on S. This is illustrated by different transition metal chalcogenides: CuCrTiS4 and CuMnTiS4 magnetic thiospinels, which are compared with magnetic oxides, Curie-Weiss (CW) paramagnetic misfit cobaltites, ruthenates, either ferromagnetic perovskite or Pauli paramagnet quadruple perovskites, and CuGa1-xMnxTe2 chalcopyrite telluride and Bi1.99Cr0.01Te3 in which diluted magnetism is induced by 3%-Mn and 1%-Cr substitution, respectively. In the case of a ferromagnet (below TC) and CW paramagnetic materials, the increase of magnetization at low T when a magnetic field is applied is accompanied by a decrease of the entropy of the carriers and hence $$\left| S\right|$$ decreases. This is consistent with the lack of MTEP in the Pauli paramagnetic quadruple perovskites. Also, no significant MTEP is observed in CuGa1-xMnxTe2 and Bi1.99Cr0.01Te3, for which Kondo-type interaction between magnetic moments and carriers prevails. In contrast, spin glass CuCrTiS4 exhibits negative MTEP like in ferromagnetic ruthenates and paramagnetic misfit cobaltites. This investigation of some chalcogenides and oxides provides key ingredients to select magnetic materials for which S benefits from spin entropy.

Summary: We report the enhancement of electron mobility and power factor for 3D topological insulator Bi2Te3 with Cobalt (Co) doping. Thermal variation of resistivity (ρ), thermopower (S), carrier concentration (nH), magneto‐resistance (MR), and magnetization measurements have been performed on synthesized Cobalt‐doped n‐type Bi2Te3, viz., Bi2−xCoxTe3 (x = 0, 0.05, and 0.1) samples. Theoretical simulation of electrical and thermal transport parameters has been done in the frame of the Boltzmann equation approach and shows satisfactory agreement with experimental results. The thermoelectric performance, as estimated through power factor is found to increase with Co doping, with an enhancement of ~47% is observed for Bi1.9Co0.1Te3 sample. The positive linear MR and nearly cusp like behaviour at low field and low temperature confirms the presence of weak anti‐localization (WAL) effects in pristine and Co‐doped Bi2Te3 samples. The field‐dependent magnetization showing a cusp‐like nature in the susceptibility data around zero field regions signifies the existence of topological surface state (TSS). MR along with magnetization data confirms the robustness of TSS with Co doping. [ABSTRACT FROM AUTHOR]

Summary: We report the enhancement of electron mobility and power factor for 3D topological insulator Bi2Te3 with Cobalt (Co) doping. Thermal variation of resistivity (ρ), thermopower (S), carrier concentration (nH), magneto‐resistance (MR), and magnetization measurements have been performed on synthesized Cobalt‐doped n‐type Bi2Te3, viz., Bi2−xCoxTe3 (x = 0, 0.05, and 0.1) samples. Theoretical simulation of electrical and thermal transport parameters has been done in the frame of the Boltzmann equation approach and shows satisfactory agreement with experimental results. The thermoelectric performance, as estimated through power factor is found to increase with Co doping, with an enhancement of ~47% is observed for Bi1.9Co0.1Te3 sample. The positive linear MR and nearly cusp like behaviour at low field and low temperature confirms the presence of weak anti‐localization (WAL) effects in pristine and Co‐doped Bi2Te3 samples. The field‐dependent magnetization showing a cusp‐like nature in the susceptibility data around zero field regions signifies the existence of topological surface state (TSS). MR along with magnetization data confirms the robustness of TSS with Co doping. [ABSTRACT FROM AUTHOR]

In this article, we report synthesis and magneto-transport analysis of Ni substituted Bi2Se3 crystals. Phase purity and crystalline growth are checked through X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Substitution of smaller Ni atoms is evident from lattice parameters which are apparently decreased with increased Ni concentration. Electron Dispersive X-ray analysis (EDAX) confirms presence of Ni atoms and Raman Spectroscopy measurements shows the presence of vibrational modes of Bi2Se3 with slight shift due to Ni substitution. Interestingly, Bi2Se3 tends to change its metallic phase to semiconducting phase with gradual Ni substitution. Magneto-resistance is also found to be drastically suppressed with Ni substitution due to semiconducting behavior of Ni substituted Bi2Se3. Magneto-conductivity of Ni substituted Bi2Se3 crystal is analyzed for the first time in this article by applying Hikami-Larkin-Nagaoka (HLN) model. [ABSTRACT FROM AUTHOR]

To study the effect of manganese non-stoichiometry at B-site, a series of manganites with compositional formula La 0.67 Sr 0.33 Mn 1±x O 3 (where x = 0, 0.05 and 0.1) was synthesized by oxalate precursor method. X-ray diffraction data confirm the rhombohedral structure of La 0.67 Sr 0.33 Mn 1±x O 3 along with minor phases of Mn 3 O 4. The average grain size is found to be 266 nm for x = 0 whereas its magnitude decreases with excess or deficiency in manganese concentration. An increase in the manganese non-stoichiometry leads to the coexistence of ferromagnetic and antiferromagnetic interactions. The effect of Mn 1±x on the magnetotransport properties could be understood on the basis of collective behaviour of magnetic spins, double exchange mechanism and ratio of Mn4+/Mn3+ ions. A crossover from negative to positive magnetoresistance behavior above metal-insulator transition temperature was observed for LSP-0.95 sample, whereas a positive magnetoresistance over the entire temperature region was noticed for LSP-1.10 sample. [ABSTRACT FROM AUTHOR]

Mixed-valent perovskite manganite has gained considerable research interest due to the increasing demand for energy storage materials. Herein, we show that colossal magneto-resistance properties of La0.7Ca0.3MnO3 (LCMO) can be changed via nickel oxide (NiO) doping. A two-step conventional solid-state reaction method is used to synthesize LCMO-10% NiO composite. The phase purity, structural, electrical (resistivity), and magneto-transport properties of as-synthesized LCMO-10% NiO composite are detailed. NiO doping shifts metal–insulator transition temperature (TMI) from 263 K to 195 K and increases resistivity. The magneto-resistance (MR) measurements showed 10% NiO doping resulted in a maximum MR of ∼ -70.32% at 200 K (near TMI) and 10 T applied magnetic field. However, -0.0849% MR is seen at 290 K (RT) and 0.3 T. The increased ∼ -63.85% MR is found at 100 K and at 10 T, which is comparatively much higher than the pristine LCMO sample. This is due to the addition of NiO in LCMO that improves physical properties (i.e., grain size).

The interplay between charges and spins may influence the dynamics of the carriers and determine their thermoelectric properties. In that respect, magneto-thermoelectric power MTEP, i.e. the measurements of the Seebeck coefficient S under the application of an external magnetic field, is a powerful technique to reveal the role of magnetic moments on S. This is illustrated by different transition metal chalcogenides: CuCrTiS4 and CuMnTiS4 magnetic thiospinels, which are compared with magnetic oxides, Curie-Weiss (CW) paramagnetic misfit cobaltites, ruthenates, either ferromagnetic perovskite or Pauli paramagnet quadruple perovskites, and CuGa1-xMnxTe2 chalcopyrite telluride and Bi1.99Cr0.01Te3 in which diluted magnetism is induced by 3%-Mn and 1%-Cr substitution, respectively. In the case of a ferromagnet (below TC) and CW paramagnetic materials, the increase of magnetization at low T when a magnetic field is applied is accompanied by a decrease of the entropy of the carriers and hence S decreases. This is consistent with the lack of MTEP in the Pauli paramagnetic quadruple perovskites. Also, no significant MTEP is observed in CuGa1-xMnxTe2 and Bi1.99Cr0.01Te3, for which Kondo-type interaction between magnetic moments and carriers prevails. In contrast, spin glass CuCrTiS4 exhibits negative MTEP like in ferromagnetic ruthenates and paramagnetic misfit cobaltites. This investigation of some chalcogenides and oxides provides key ingredients to select magnetic materials for which S benefits from spin entropy. [ABSTRACT FROM AUTHOR]

Here, we report the growth and characterization of single crystals of NdxSb2-xTe3 (x = 0 and 0.1), by solid-state reaction route via self-flux method. The phase and layered growth are confirmed through X-ray diffraction and scanning electron microscopy respectively. A slight contraction in lattice parameters is seen after Nd doping. Also a minute shift in vibrational modes of recorded Raman spectra has been observed by doping of Nd in Sb2Te3. The magneto-resistance values under magnetic field of 5 Tesla for Sb2Te3 are 75% at 2.5 K and 60% at 20 K, but only 40% at 5 K for Nd0.1Sb1.9Te3. DC magnetic measurements exhibit expected diamagnetic and paramagnetic behaviors for pure and Nd doped crystals respectively. A cusp-like behavior is observed in magneto-conductivity of both pure and Nd doped crystals at low magnetic fields (< 1 Tesla) which is analyzed using Hikami-Larkin-Nagaoka (HLN) model. For Sb2Te3, the fitted parameters α are −1.02 and −0.58 and the phase coherence lengths Lφ are 50.8(6)nm and 34.9(8)nm at temperatures 2.5 and 20 K respectively. For Nd0.1Sb1.9Te3, α is −0.29 and Lφ is 27.2(1)nm at 5 K. The α values clearly show the presence of weak anti-localization effect in both pure and Nd doped samples. Also with Nd doping, the contribution of bulk states increases in addition to conducting surface states in overall conduction mechanism. [ABSTRACT FROM AUTHOR]

Topological insulators (TIs) a new quantum state of matter predicted to have an interesting surface properties. In this report, we study the surface properties of Bi 2 Te 2 Se (BTS) topological insulators thin films. Raman measurements on BTS thin film show a strong intensity of A 1 1 g ( ∼ 62 cm - 1 ), E 2 g ( ∼ 123 cm - 1 ) and A 2 1 g ( ∼ 170 cm - 1 ) modes in addition to A 2 1 u ( ∼ 140 cm - 1 ) modes. Elemental analyses were done using X-ray photoelectron spectroscopy (XPS). Resistance versus temperature measurement reveal a magnetic field-driven metallic behavior at high temperatures and further analysis on magnetic measurement shows a diamagnetic nature of BTS film. The magneto-resistance measurements on these films exhibit a weak antilocalization effect that arises due to quantum interfering nature of topological insulators and the measured weak anti-localization effect is fitted using Hikami–Larkin–Nagaoka (HLN) model. [ABSTRACT FROM AUTHOR]

We report the chemical synthesis of Cr-doped ZnS nanocrystallites without using any capping ligand/surfactant. An unusual increase in bandgap observed for Cr-doped samples was understood in terms of the Burstein–Moss effect. Additionally, 4A2(F) → 4T1(F) and 4A2(F) → 4T2(F) transitions in the absorption spectra confirmed the substitution of Cr3+ ions at the octahedrally coordinated interstitial sites. Photoluminescence study showed a large amount of Zn vacancies owing to the incorporation of Cr3+ ions which intensified the self-activated blue–green luminescence. Room-temperature magnetization showed FM ordering up to the 2% Cr doping, which gradually transformed into paramagnetic behavior at higher values and became more enhanced in the low-temperature range. Thus, in the present synthesis method, the FM order could only be observed up to the 2% Cr doping concentration. Also, the activation energy was observed to increase with the increase of Cr doping concentration. [ABSTRACT FROM AUTHOR]

Here, we report the structural and low temperature electrical properties of La0.8Sr0.2MnO3 (LSMO), Bi0.95Dy0.05FeO3 (BDFO) and their composite (0.5) LSMO + (0.5) BDFO prepared via solid-state reaction route. X-ray diffraction (XRD) data studies infers that both the compounds LSMO and BDFO are single phased in nature. Further XRD data analysis reveal that both these compounds display their presence in the composite sample. Both the parent samples of the composite were observed to have crystallized in rhombohedral (R3c) structure. The lattice structure was further verified via Raman Spectroscopic measurement technique. Low temperature transport properties study establishes the semiconducting nature of the composite. The dc resistivity data of ferromagnetic mettalic LSMO compound suggests that the electron–electron scattering is predominant in the metallic region whereas the semiconducting region in the composite sample [(0.5) LSMO + (0.5) BDFO] is well described using small polaron hopping and Mott's variable range hopping (VRH) models. Activation energy Ep was found to decrease with increase in magnetic field from 0 to 8T attributed to the decrease in the values of charge localization. The density of states Increases with magnetic field attributed to the suppression of magnetic domain scattering explained via Mott's VRH mechanism. High MR% is observed in both the LSMO sample and the composite one which increases with decrease in temperature. [ABSTRACT FROM AUTHOR]

• Ion beam modification has been studied for CoFe/n-Si interfaces. • Ordered array of grains has been observed which is due to recrystallization phenomenon. • Drastic change in M-H loops from antiferromagnetic coupled phase to ferromagnetic phase has been observed. • A significant electronic transport has been observed with and without magnetic field. • Magneto-resistance of ∼7% has been estimated for the structure. Interfacial structures of ferromagnetic (FM) metal combined with semiconductor (SC) are key step for realizing spintronic devices where spin degree of freedom can also be utilized in addition to the charge of electron. Tailoring of such interfaces (of FM/SC) is known to tune the magnetic, optical, structural and transport properties. Swift heavy ion irradiation (SHI) can be used as a potential tool to tailor the interfaces. In our present work, effect of ion beam irradiation (100 meV Ni+7 ions) on the CoFe/n-Si interfacial structures had been studied. Thin films of CoFe was deposited by electron beam evaporation technique using CoFe metallic alloy on Si substrate. The realized interfacial structure was characterized from structural, morphological and magnetic point of view. The surface exhibits grainy structure with very fine domain (∼50 nm) on the irradiation. Electronic transport study across the interface shows an increase in current on irradiation with significant magnetic field sensitivity and a magnetoresistance of ∼7% has been observed. The observed results of increased magnetization and enhanced magnetic field sensitivity has been understood in the realm of irradiation induced interfacial intermixing across the interfaces. The chemical phases formed and nature of the interface as a result of irradiation was probed by X-ray photoelectron spectroscopy (XPS) study which confirms the formation of various silicide phases along with the metallic phase. The results were also compared with our earlier studies [15–16] on CoFe/n-Si system and found that fluence of 1 × 1011 ions/cm2 seems significant to result in interesting magnetic and transport properties without much damage to interface. [ABSTRACT FROM AUTHOR]

Double perovskite (DP) oxide material receive extensive research interest due to exciting physical properties with potential technological application. 3 d based DP oxides are promising for exciting physics like magnetodielectric, ferroelectric, Griffiths phase, etc., specially Co/Mn DPs are gaining much research interest. In this paper we present the study of magnetic phase and transport properties in nano-crystalline Pr 2 CoMnO 6 a 3 d based double perovskite compound. This material shows a paramagnetic (PM) to ferromagnetic (FM) phase transition below 173 K marked by a rapid increase in magnetic moment due to spin ordering. We found divergence in inverse magnetic susceptibility (χ − 1) from Curie–Weiss behavior around 206 K which indicates the evolution of Griffiths phase before actual PM-FM transition. We found that the Griffiths phase suppressed with increasing applied magnetic field. For the understanding of charge transport in this material we have measured temperature dependent electrical resistivity. Pr 2 CoMnO 6 is a strong insulator where resistivity increase abruptly below magnetic phase transition. To understand the effect of magnetic field on transport behavior we have also measured the magnetoresistance (MR) at different temperatures. Sample shows the negative MR with maximum value ∼22% under applied magnetic field of 50 kOe at 125 K. MR follows quadratic field dependency above T c however below T c the MR shows deviation from this field dependency at low field. • Pr 2 CoMnO 6 shows paramagnetic to ferromagnetic phase transition around 173 K. • Griffiths phase is observed in this material marked by deviation in magnetic susceptibility. • Pr 2 CoMnO 6 is a strong insulator where resistivity shows inverse temperature dependency. • Material shows large magnetoresistance below T c ∼ 22 % in 50 kOe at 125 K. [ABSTRACT FROM AUTHOR]

Diluted magnetic semiconductors (DMSs), having interesting magnetic/transport properties, are currently being explored in photocatalytic application as well. This report presents photocatalytic and low temperature magnetic/transport study of chemically synthesized 3-5 nm sized cubic Zn1-xCuxS (0 ≤ x ≤ 0.04) DMS nanoparticles. Both studies have their own importance, former relates to dye degradation, while later attempts to understand origin of magnetic behavior in DMSs (which is still debatable). As a photocatalyst, Cu doped ZnS NPs showed enhanced degradation-efficiency for methylene blue dye. Magnetization study showed enhanced magnetic moment in Cu doped samples, which in the low temperature regime got further enhanced and was understood due to defect induced ferromagnetism. Low temperature transport study showed the decrease in resistivity of the Cu doped samples and was understood in terms of defects states created due to doping of the Cu ions and governed by conduction mechanism, namely thermal activation and variable range hopping. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Synthesis of bulk La 0.7 Ba 0.3 Mn 1−x Al x O 3 (0 ≤ x ≤ 0.15) compounds with Al3+ substitution at Mn-site. • Significant crystal structural-relaxations in terms of bond-length, bond-angle and tolerance factor values. • Methodological investigation of magneto-transport and thermoelectric properties. • Enhanced magnetoresistance and determination of several other electronic-transport parameters that govern charge conduction. • Analysis of thermoelectric power via five degree polynomial fit and SPH/VRH polaron hopping mechanism. Abstract This report presents the structural, magnetoresistance, electrical and thermal transport properties of Aluminium substituted La 0.7 Ba 0.3 Mn 1−x Al x O 3 (0 ≤ x ≤ 0.15) compounds synthesized by solid state reaction method. To obtain crystallographic parameters, the X-ray diffraction patterns are fitted in R-3c space group with Rietveld refinement method. The resistivity and magneto-transport measurements are performed using standard four-probe assembly with and without magnetic fields. The peak resistivity ρ peak is noted at Metal-Insulator Transition temperature (T MI) and lowering in T MI is observed for higher concentrations of Al3+. The resistivity data have been analyzed in two parts. Firstly, in the metallic region below T MI the resistivity data is fitted with three degree polynomial. Secondly, in the semiconducting region above T MI data have been fitted with Variable Range Hopping (VRH) and Small Polaron Hopping (SPH) models. The Seebeck coefficients found to be positive throughout the temperature range (10 K–300 K) with holes as dominating charge carriers. Similar to the resistivity profile, in metallic region the thermo-power is explained with qualitative model based on diffusion, magnon-drag, phonon-drag and spin fluctuation contributions whereas the semiconducting region is explained with small polaron hopping model. [ABSTRACT FROM AUTHOR]

The parametric torque presents a promising recording mechanism for MRAM, complementing Spin Transfer Torque and Spin Orbit Torque, enabling magnetization reversal in a nanomagnet using a DC electrical current. Its resonance nature allows for optimization of magnetization reversal at a lower current, presenting an opportunity for a lower recording current and, therefore, for efficient and high-performance operation in modern MRAM technology. The in-plane magnetic field generated by spin accumulation serves as the driving force behind this torque. Experimental measurements of the current-induced in-plane magnetic field in the FeB nanomagnet reveal its magnitude to be around 40 Gauss at a current density of 25 mA/ μ m 2 , a value adequate for facilitating parametric magnetization reversal. The parametric torque is analytically calculated by solving the Landau–Lifshitz equation. Analytical calculations demonstrate its potential in advancing modern MRAM technology. • A novel resonance torque capable of magnetization reversal via DC electrical current is introduced. • Parametric torque, complementing Spin Transfer Torque and Spin Orbit Torque, enhances MRAM's recording capabilities. • Unlike Damp-Like and Field-Like torques, Parametric torque occurs only under specific identified conditions. • Experimental measurement of the spin-accumulation-induced magnetic field in a FeCoB nanomagnet is presented. • Parametric torque is analytically calculated via a solution of Landau–Lifshitz equation. [ABSTRACT FROM AUTHOR]

• Ca 4 Mn 3-x W x O 10 (x = 0, 0.05, 0.10) synthesised using a solid-state reaction technique. • Rietveld refinements of high-quality powder XRD show good convergences. • X-ray photoelectron spectroscopy show the mixed oxidation state of Mn cations. • Semiconducting behaviour of the samples is consistent with the VRH and SPH models. • Thermopower study reveals that all samples have a small polaron hopping mechanism. This report comprehensively investigates the crystal structure, magnetism, and transport properties of tungsten (W6+) substituted polycrystalline Ca 4 Mn 3-x W x O 10 (x = 0, 0.05, 0.1) compounds. The compounds were synthesized using the solid-state method and found to exhibit a single-phase orthorhombic structure confirmed by the Rietveld refinement. The substitution of (W6+) induces a change in the Mn octahedron and enhances the unit cell volume. The morphology indicates the crystalline nature of all the samples. The FTIR spectroscopic study revealed the position of the IR bands, which is highly sensitive to the oxidation state of Mn-ions. The shift to higher wavenumbers indicates reduced oxidation from Mn4+ to Mn3+ species. The appearance of the Mn4+ oxidation state in (x = 0) and the emergence of Mn3+ on W6+ substitution for (x = 0.05, 0.1) compounds are explored. The electrical resistivity plots revealed that compounds are semiconducting. The magnitude of resistivity decreases with W6+ substitution. The reported compounds exhibit a significant negative magneto-resistance towards lower temperatures. The compounds also demonstrate short-range ferromagnetic (FM) behavior attributed to the charge compensation effect's double exchange interaction (DE) connecting Mn4+ and Mn3+. The negative value of thermoelectric power (S) suggests the presence of charge carriers such as electrons, and the value of S first increased and then decreased in doped samples. The conduction in the studied compound is attributed to small polaron hopping. [ABSTRACT FROM AUTHOR]

We report a new member of topological insulator (TI) family i.e. Mn 2 Sb 2 Te 5 , which belongs to MnSb 2 Te 4 family and is a sister compound of Mn 2 Bi 2 Te 5 . An antiferromagnetic layer of (MnTe) 2 has been inserted between quintuple layers of Sb 2 Te 3 . The crystal structure and chemical composition of as grown Mn 2 Sb 2 Te 5 crystal is experimentally visualized by single crystal x-ray diffractometer and field emission scanning electron microscopy. The valence states of individual constituents i.e., Mn, Sb and Te are ascertained through x-ray photo electron spectroscopy. Different vibrational modes of Mn 2 Sb 2 Te 5 are elucidated through Raman spectroscopy. Temperature-dependent resistivity ρ ( T ) of Mn 2 Sb 2 Te 5 resulted in metallic behavior of the same with an up-turn at below around 20 K. Further, the magneto-transport ρ ( T ) vs H of the same exhibited negative magneto-resistance (MR) at low temperatures below 20 K and small positive at higher temperatures. The low Temperature -ve MR starts decreasing at higher fields. The magnetic moment as a function of temperature at 100 Oe and 1 kOe showed anti-ferromagnetism (AFM) like down turn cusps at around 20 K and 10 K. The isothermal magnetization showed AFM like loops with some embedded ferromagnetic/paramagnetic (PM) domains at 5 K and purely PM like at 100 K. The studied Mn 2 Sb 2 Te 5 clearly exhibited the characteristics of a magnetic TI., (© 2023 IOP Publishing Ltd.)

Abstract In this study, we have investigated the crystallographic structure and the temperature-dependent resistivity of an electron doped La 1-x Zr x MnO 3 manganite system. X-ray photoemission spectroscopy (XPS) for core level study has been carried out to confirm the electron doping. The results of XPS core level study suggests that Zr ions are in the tetra-valent state and Mn ions are forced to be in a mixed state of Mn3+ and Mn2+. Rietveld refinement of X-ray powder diffraction results have confirmed the rhombohedral crystal symmetry of the samples with space group R-3c. The temperature dependent resistivity and magnetization plots exhibit insulator to metal transition (MIT) accompanied with Paramagnetic to Ferromagnetic transition (T c). Three independent MIT transitions have been observed, the first sharp transition at T P1 showed a strong correlation with the magnetic transition T c confirming that the intrinsic MIT happened at T P1. The insulating behaviour below T 1 has been attributed to the competition between the short range orbital/charge order and the long range FM order. The transition at lower temperature T P2 may be attributed to the percolative transport of charge carriers through ferromagnetic metallic domains. The third upturn transition assigned as T min has been ascribed to combined effect of electron-electron and Kondo interactions, the detailed qualitative analysis and discussion of which is under preparation. Highlights • Electron doped manganite system La 1-x Zr x MnO 3 were synthesized using solid state reaction method. • The system has a rhombohedral crystal symmetry with space group R-3c. • XPS core level study suggests electron doping of the system. • The system exhibits metal to insulator (MIT) transition accompanied by the Ferromagnetic (FM) to Paramagnetic (PM) transition. • Three independent MIT transitions have been observed, attributed to different physical phenomenon. [ABSTRACT FROM AUTHOR]

The electric and thermal transport properties (electric resistivity ρ, magneto-resistance MR , Hall coefficient R H and anomalous Hall effect, thermal conductivity Κ and Seebeck coefficient S ) of the off-stoichiometric Ni 1.92 Mn 1.56 Sn 0.52 Heusler alloy were measured in a wide temperature and magnetic field range. The simultaneous measurement of several transport and magnetic properties offers a possibility to combine information arising from the received experimental results. The phonon and the charge carriers parts of complex temperature dependence of thermal conductivity K(T) were consistently separated using the Lorentz factor and temperature dependence of resistivity ρ (T) . The positive values of the Hall coefficient R H has been determined in martensite phase of the alloy at low temperatures. R H reaches zero value at temperature range where the so-called “paramagnetic gap” was observed and the negative value of R H was detected in austenite phase. Temperature dependence of the Hall coefficient R H (T) was used to derive both, the density and the mobility of charge carriers. The standard relations were used to describe the measured temperature dependence of the Seebeck coefficient. All the received result point to an important role of changes in electronic structure of the alloy in all the studied transport effects. A scenario of the complex behavior of the transport properties of the Heusler alloy based on a possible existence of an energy gap in electronic structure is discussed. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the resistivity of bilayer manganite LaSr 2 Mn 2 O 7 around the metal–insulator-like transition was systematically calculated as a function of temperature and applied magnetic field. A typical mathematical function (Gauss function) was used for fitting the experimental data. The theoretical values simulated in this work such as – metal–insulator transition temperature (T p) and maximum resistivity (ρ max) showed promising agreement with the experimental data. [ABSTRACT FROM AUTHOR]

Magnetism in dilute magnetic semiconductors (DMSs) has been a controversial topic since its discovery. There are many models which predict the origin of room temperature ferromagnetism (RTFM) in TM doped wide band gap semiconductors. Here, we report RTFM in chemically synthesized cubic Zn 1-x Ni x S (0 ≤ x ≤ 0.08) DMS nanoparticles of ∼3–5 nm size. Ferromagnetic behavior (at 300 K and 5 K) was found to increase with the increase in Ni doping concentration and was understood due to defect induced ferromagnetism. The low temperature magnetization measurement (ZFC-FC) shows that the nanoparticles are strongly coupled by magnetic interactions. Optical studies showed decrease in the energy bandgap along with the presence of sulfur and zinc vacancies and surface defects. Low temperature resistivity measurement depicted the semiconducting nature of the synthesized samples. With increase in doping concentration, an increase in the resistive behavior was observed which was explained in the realm of defects states created due to doping of the Ni ions. [ABSTRACT FROM AUTHOR]

We report the magneto-conductivity analysis at different temperatures under a magnetic field of up to 5 T of a well- characterized Bi2Te3 crystal. Details of crystal growth and various physical properties including high linear magneto-resistance are already reported by some of us. To elaborate upon the transport properties of Bi2Te3 crystal, the magneto-conductivity is fitted to the known Hikami-Larkin-Nagaoka (HLN) equation and it is found that the conduction mechanism is dominated by both surface-driven weak anti-localization (WAL) and the bulk weak localization (WL) states. The value of HLN equation coefficient (α) signifying the type of localization (WL, WAL or both WL and WAL) falls within the range of − 0.5 to − 1.5. In our case, the low-field (± 0.25 T) fitting of studied crystal exhibited a value of α close to − 0.86 for studied temperatures of up to 50 K, indicating both WAL and WL contributions. The phase coherence length (lφ) is found to decrease from 98.266 to 40.314 nm with increasing temperature. Summarily, the short letter reports the fact that bulk Bi2Te3 follows the HLN equation and quantitative analysis of the same facilitates to know the quality of studied crystal in terms of WAL to WL contributions and thus the surface to bulk conduction ratio. [ABSTRACT FROM AUTHOR]

SrIrO 3 (SIO) is one of the materials known to exhibit a high spin-orbit coupling with correlated semi-metallic ground state, along with the topological states, as proven in recent times. In this regard, the SIO thin films grown by us on SrTiO 3 (001) at certain deposition conditions, exhibit a low temperature magneto-transport behavior which is analogous to the materials with topological states. Further, we have explored various deposition conditions of SIO such as partial pressure of O 2 and different temperatures of growth for different thickness of SIO. In addition, from the electrical transport properties, SIO thin films found to exhibit semi-metallic nature with either insulating-like or a crossover from metal-like to insulating-like behavior based on the conditions chosen for the growth. Moreover, the magneto-transport data of various SIO thin films are found to be obeying the usual B 2 (Lorentzian) behavior in majority of the cases. At the same time, we have also observed the weak-localization and weak-antilocalization effects; along with a linear magneto-resistance at low temperature ranges. Thus, from our extensive measurements, it becomes clear that SIO thin films can exhibit wide varieties of magneto-transport properties based on the deposition conditions. Plethora of interesting properties exhibited by the highly spin-orbit coupled SIO epitaxial thin films at lower temperatures in the presence of magnetic field makes the material to be promising for the future applications in the field of spintronics. [ABSTRACT FROM AUTHOR]

This paper reports the synthesis of different particle size La 0.7 Sr 0.3 MnO 3 (LSMO) nanoparticles using non-aqueous sol gel synthesis route by calcination at temperatures 750 °C, 850 °C and 950 °C. In the present work, the effect of particle size of LSMO nanoparticles on its structural, magnetic and transport properties has been studied in detail. The X-ray diffraction analysis confirms the formation of LSMO nanoparticles having rhombohedral ( R 3 ̅ c ) structure with average particle size of 20 nm, 22.5 nm and 25.6 nm. An increase in magnetization and decrease in coercivity with increase in particle size is attributed to the magnetically disordered surface layer. The bifurcation in ZFC-FC magnetization indicates the possibility of spin glass like behavior of the LSMO nanoparticles. The effect of particle size on the resistivity and magnetoresistance were studied by using different conduction mechanism for different temperature regions. The upturn in the ρ-T curve at lower temperatures was explained by using Kondo-like transport mechanism. The maximum LFMR achieved was 32.3% at a field of 1 T at 10 K for 20 nm LSMO nanoparticle. [ABSTRACT FROM AUTHOR]

Bulk metallic samples were synthesized from different binary powder mixtures consisting of elemental Cu, Co, and Fe using severe plastic deformation. Small particles of the ferromagnetic phase originate in the conductive Cu phase, either by incomplete dissolution or by segregation phenomena during the deformation process. These small particles are known to give rise to granular giant magneto-resistance. Taking advantage of the simple production process, it is possible to perform a systematic study on the influence of processing parameters and material compositions on the magneto-resistance. Furthermore, it is feasible to tune the magneto-resistive behavior as a function of the specimens’ chemical composition. It was found that specimens of low ferromagnetic content show an almost isotropic drop in resistance in a magnetic field. With increasing ferromagnetic content, percolating ferromagnetic phases cause an anisotropy of the magneto-resistance. By changing the parameters of the high pressure torsion process, i.e., sample size, deformation temperature, and strain rate, it is possible to tailor the magnitude of giant magneto-resistance. A decrease in room temperature resistivity of ~3.5% was found for a bulk specimen containing an approximately equiatomic fraction of Co and Cu.

Electrical resistivity studies reveal large granular effects in the superconductivity behaviour of the electron-doped cuprate, NdCeCuO, in polycrystalline form, much larger than their hole-doped counterparts. With the aim of investigating inter-granular coupling, as well as its variation with magnetic field and addition of Ag, AC susceptibility and magneto-resistance (MR) studies have been carried out on NdCeCuO + Ag composite system. A comparative study of the superconducting properties of the NdCeCuO + Ag composite system for Ag = 0, 5 and 15 wt%, including upper critical field [ H (0)], has been carried out and is presented. [ABSTRACT FROM AUTHOR]

In this article, iron nanowire is synthesized by reducing Fe2+ ion with excessive sodium borohydride in deionized aqueous solution. A kind of dimorphic magnetorheological gel is prepared by partial substitution of carbonyl iron particles with Fe nanowires. Several experimental devices based on the dimorphic magnetorheological gel were fabricated, and the magneto-resistance characteristics under a magnetic field of those devices are systematically tested to research the influence of the Fe nanowire on the conductivity of magnetorheological gel. The experimental results indicated that by adding a certain amount of Fe nanowire, the conductivity of the dimorphic magnetorheological gel can be greatly improved. Moreover, it can be seen that the conductivity of sample 4 (with 6 wt.% Fe nanowire) is increased by about 100 times than sample 1 (without Fe nanowire). The mechanism of Fe nanowire enhances the conductivity of the dimorphic magnetorheological gel, which is investigated by microstructure analysis. [ABSTRACT FROM AUTHOR]

We report the effect of MgO phase on structural, electric and thermo electric properties of La 0.8 Sr 0.2 MnO 3 (LSMO) and manganite matrix-based composite series (1− x ) La 0.7 Ca 0.2 Sr 0.1 MnO 3 + ( x ) MgO with x = 0.0, 0.05, 0.10, 0.15 (abbreviated as LCSMO - MgO) synthesized by solid-state reaction method. X-ray diffraction (XRD) data infers that manganite LSMO compound possesses a rhombohedrally-distorted structure (space group R 3 c ), LCSMO has an orthorhombic structure ( Pnma space group) while to that MgO compound crystallizes in cubic structure (space group Fd3m ). XRD shows coexistence of MgO and La 0.7 Ca 0.2 Sr 0.1 MnO 3 phases in doped composites through their characteristic peaks. The temperature dependence of resistivity shows that the transport behavior of the composites is governed by the grain boundaries. These composites shows metal–insulator transitions at T = T MI which decreases with increasing MgO concentration. The magnetoresistance (MR) in this system increases with increasing MgO content, showing a maximum value (91% at 50 K and at lower fields) for (0.85) LCSMO - (0.15) MgO sample, which is larger than the largest MR value of pure La 0.7 Ca 0.2 Sr 0.1 MnO 3 (44% at 50 K). From thermoelectric power measurements, it is observed that electron-magnon scattering process is dominant mechanism in the low temperature region. [ABSTRACT FROM AUTHOR]

We report synthesis, structural details and electrical transport properties of topological insulator Bi 2 Te 3 . The single crystalline specimens of Bi 2 Te 3 are obtained from high temperature (950 °C) melt and slow cooling (2 °C/hour). The resultant crystals were shiny, one piece (few cm) and of bright silver color. The Bi 2 Te 3 crystal is found to be perfect with clear [00l] alignment. The powder XRD pattern being carried out on crushed crystals showed that Bi 2 Te 3 crystallized in R3̅m symmetry with a = b =4.3866(2) Å, c =30.4978(13) Å and γ =120°. The Bi position is refined to (0, 0, 0.4038 (9)) at Wyckoff position 6 c and of Te are (0, 0, 0) at Wyckoff position 3 a and at (0, 0, 0.2039(8)) at 6 c . Ambient pressure and low temperature (down to 2 K) electrical transport measurements revealed metallic behavior. Magneto transport measurements under magnetic field showed huge non saturating magneto resistance (MR) reaching up to 250% at 2.5 K and under 50 kOe field. Summarily, the short communication clearly demonstrates that Bi 2 Te 3 topological insulator exhibit non-saturating large positive MR at low temperature of say below 10 K. The non saturating MR is seen right up to room temperature albeit with much decreased magnitude. Worth mentioning is the fact that these crystals are bulk in nature and hence the anomalous MR is clearly an intrinsic property and not due to the size effect as reported for nano-wires or thin films of the same. [ABSTRACT FROM AUTHOR]

In this letter, we report on the growth and characterization of bulk Bi Se single crystals. The studied Bi Se crystals are grown by the self-flux method through the solid-state reaction from high-temperature (950 °C) melt of constituent elements and slow cooling (2 ℃/h). The resultant crystals are shiny and grown in the [00l] direction, as evidenced from surface XRD. Detailed Reitveld analysis of powder X-ray diffraction (PXRD) of the crystals showed that these are crystallized in the rhombohedral crystal structure with a space group of R3m (D5), and the lattice parameters are a = 4.14 (2), b = 4.14 (2), and c = 28.7010 (7) Å. Temperature versus resistivity ( ρ− T) plots revealed metallic conduction down to 2 K, with typical room temperature resistivity ( ρ ) of around 0.53 m Ω-cm and residual resistivity ( ρ ) of 0.12 m Ω-cm. Resistivity under magnetic field [ ρ( T) H] measurements exhibited large + ve magneto-resistance right from 2 to 200 K. Isothermal magneto-resistance [ ρH] measurements at 2, 100, and 200 K exhibited magneto-resistance (MR) of up to 240 %, 130 %, and 60 %, respectively, at 14 T. Further, the MR plots are nonsaturating and linear with the field at all temperatures. At 2 K, the MR plots showed clear quantum oscillations at above say 10 T applied field. Also, the Kohler plots, i.e., Δ ρ/ ρ versus B/ ρ, were seen consolidating on one plot. Interestingly, the studied Bi Se single crystal exhibited the Shubnikov-de Haas (SdH) oscillations at 2 K under different applied magnetic fields ranging from 4 to 14 T. [ABSTRACT FROM AUTHOR]

Magnetic and magneto-transport properties of thin layers of the (Ga,Mn)(Bi,As) quaternary dilute magnetic semiconductor grown by the low-temperature molecular-beam epitaxy technique on GaAs substrates have been investigated. Ferromagnetic Curie temperature and magneto-crystalline anisotropy of the layers have been examined by using magneto-optical Kerr effect magnetometry and low-temperature magneto-transport measurements. Post-growth annealing treatment of the layers has been shown to enhance the hole concentration and Curie temperature in the layers. A significant increase in the magnitude of magneto-transport effects caused by incorporation of a small amount of Bi into the (Ga,Mn)As layers, revealed in the planar Hall effect (PHE) measurements, is interpreted as a result of enhanced spin-orbit coupling in the (Ga,Mn)(Bi,As) layers. A two-state behaviour of the planar Hall resistance at zero magnetic field provides its usefulness for applications in non-volatile memory devices. [ABSTRACT FROM AUTHOR]

In the present paper we studied the structural, magnetotransport and thermopower properties of a series of polycrystalline La 0.7−x Sm x Ba 0.3 MnO 3 (0≤x≤0.2) compounds which were synthesized by conventional solid state reaction techniques. The Rietveld refinement of the X-ray diffraction pattern predicts the formation of single-phase compositions and doping of La 3+ by Sm 3+ ion converted the chemical structure form rhombohedral ( R-3C ) to orthorhombic ( Imma ) The scanning electron microscopy show clean smooth and densified structure images be a sign of good crystalline nature of the samples. The temperature dependent electrical resistivity is measured by standard four-probe method between 5 and 300 K exhibits Metal–Insulator Transition MIT which shows the decreasing trend with increasing Sm doping content and metallic state (TT p2 ) are explained within the framework of variable range hopping (VRH) and small polaron hopping (SPH) models. The application of magnetic field suppresses the resistivity in entire temperature range and with increasing the Sm 3+ content the samples showed very high magnetoresistance. The thermoelectric power (S) of the reported samples exhibit a crossover from positive to negative value and it increases in doped samples. The analysis of thermoelectric power data confirms the applicability of the small polaron hopping model in high temperature region and in low temperature fitted to an equation containing diffusion, magnon drag, phonon drag and electron-spin fluctuation term. An appropriate justification for the observed behavior is specified. [ABSTRACT FROM AUTHOR]

We investigated the electrical transport properties of epitaxial La 0.7 Ca 0.3 MnO 3 thin films grown by metal organic deposition process on LaAlO 3 single crystalline substrates. To explain the coexistence of ferromagnetic (FM)-metallic and paramagnetic (PM) -insulator phases in the same specimen, the temperature dependence of resistivity was simulated by the phenomenological percolation model which is based on the phase segregation of FM-metallic to PM-insulator. The temperature dependence of resistivity ( ρ ( T ) ) curves can be well fitted by ρ ( T ) = ρ FM f + ρ PM ( 1 − f ) with ρ FM is the resistivity of the FM phase below the Curie temperature ( T C ), ρ PM is the resistivity of the PM phase above T C and “ f ” is the FM volume fraction. The obtained fitting parameters have been correlated to the change in the strain in the films having various thicknesses. The ferromagnetic volume fraction ( f (T)) and the reduced magnetization m ( T ) show monotonic and “similar” behaviors. [ABSTRACT FROM AUTHOR]

Structural, magnetic and magneto transport properties of La 1-y Sr y Mn 0.5 Co 0·5 O 3±δ perovskites prepared by aqueous solution combustion synthesis were studied in detail. The effect of Sr doping on the properties of these perovskites was investigated. As-prepared perovskites were characterized using X-ray diffraction for single phase formation. Magnetic study was carried out for in depth analysis of the magnetic properties. AC susceptibility study shows a change in the behavior of undoped and doped compounds in low temperature region. Ferromagnetic interactions was found to increase in the low temperature region in the doped compounds compared to that in the undoped compound. The measurements on resistivity showed reduction with Sr doping up to y = 0.5. This is attributed to the high spin stabilized Co3+ ions which enhance the ferromagnetic interactions and the hopping probability of e g charge carriers. [ABSTRACT FROM AUTHOR]

In this work, we developed and fabricated a paper-based anisotropic magneto-resistive sensor using a sputtered permalloy (Ni 81 Fe 19 ) thin film. To interpret the characteristics of the sensor, we proposed a computational model to capture the influence of the stochastic fiber network of the paper surface and to explain the physics behind the empirically observed difference in paper-based anisotropic magneto-resistance (AMR). Using the model, we verified two main empirical observations: (1) The stochastic fiber network of the paper substrate induces a shift of 45 ∘ in the AMR response of the paper-based Ni 81 Fe 19 thin film compared to a Ni 81 Fe 19 film on a smooth surface as long as the fibrous topography has not become buried. (2) The ratio of magnitudes of AMR peaks at different anisotropy angles and the inverted AMR peak at the 90 ∘ -anisotropy angle are explained through the superposition of the responses of Ni 81 Fe 19 inheriting the fibrous topography and smoother Ni 81 Fe 19 on buried fibrous topographies. As for the sensitivity and reproducibility of the sensor signal, we obtained a maximum AMR peak of 0.4 % , min-max sensitivity range of [ 0.17 , 0.26 ] % , average asymmetry of peak location of 2.7 kA m within two consecutive magnetic loading cycles, and a deviation of 250⁻850 A m of peak location across several anisotropy angles at a base resistance of ∼100 Ω . Last, we demonstrated the usability of the sensor in two educational application examples: a textbook clicker and interactive braille flashcards.

We have synthesized a series of Sm 0.55 Sr 0.45−x Ag x MnO 3 (x = 0 & 0.15) by conventional solid state reaction method to scrutinize the effect of monovalent Ag + as a replacement of Sr 2+ ion on structural, electrical, magnetotransport and thermoelectric properties. The structural parameters obtained using Rietveld refinement of X-ray diffraction data which showed perovskite structure having orthorhombic ( Pnma ) symmetry without any detectable impurity phase. It is observed that M ZFC and M FC curves become more manifested as Ag + content is increased which indicates an increase in magnetic frustration arising due to bending of Mn-O-Mn bond. The M-H plots show the narrow hysteresis loops which indicate the soft ferromagnetic nature. Magnetic studies also show that the Curie temperature T C is found to decrease with Ag + content. The metal–insulator transition temperature (T MI ) is observed which decreases with the increase of Ag + content when magnetic field is applied. The resistivity data in high temperature region are explained within the framework of variable range hopping (VRH) and small polaron hopping (SPH) models. The thermoelectric power (S) of the reported samples exhibits a crossover from positive to negative value and value of S increases in doped samples. The analysis of thermoelectric power data confirms that the small polaron hopping model in high temperature region and at low temperature electron–magnon scattering is the dominating in the FM region. With increasing the Ag + content the samples showed very high magneto-resistance (MR%) and temperature coefficient of resistance (TCR%) which make the compound more promising for scientific and technological applications. [ABSTRACT FROM AUTHOR]

At this work, spin- and valley-dependent electron transport through graphene and silicene layers are studied in the presence of Rashba spin- orbit coupling. We find that the transport properties of the related ferromagnetic/normal/ferromagnetic structure depend on the relevant parameters. A fully valley- and spin- polarized current is obtained. As another result, Rashba spin-orbit interaction plays important role in controlling the transmission characteristics. [ABSTRACT FROM AUTHOR]

We report a new fabrication strategy to obtain large area continuous NPGs-on-substrate combining graphene-on-substrate industrial techniques and swift-ion beam irradiation (SHI). Graphene membranes were synthesized on the Cu substrate and afterwards a 600 nm layer of PMMA was spin-coated on the surface to complete the PMMA-Graphene-Cu stack. The PMMA-graphene-Cu trilayer was exposed to a flow of Au heavy ions that penetrate through the entire thickness of both polymer layer and the graphene sheet creating ion-tracks and damages. A consecutive track-etching technique is used with an adequate revealing agent for PMMA, IsoPropyl Alcohol (IPA), to selectively dissolve the latent tracks and damages created during SHI irradiation in the insulating material and the graphene sheet. Resulting from SHI irradiation and track-etching, the graphene nanopores are thus perfectly aligned to the PMMA nanopores, providing, after cupper dissolution, a composite that features both well-defined and truly 2-dimensional nanopores in the graphene layer but that can be handled as a normal polymer film. [ABSTRACT FROM AUTHOR]

We report on magneto-transport experiments in a high-quality sample of highly-oriented pyrolytic graphite (HOPG). Magneto-resistance and Hall resistivity measurements were carried out in magnetic inductions up to B = 9 T applied parallel to the c -axis at fixed temperatures between T =2 K and T =12 K. The sample was submitted to three subsequent irradiations with As ions. The implanted As contents were 2.5, 5 and 10 at% at the maximum of the distribution profile. Experiments were performed after each implantation stage. Shubnikov-de Haas (SdH) oscillations were observed in both the magneto-resistance and Hall-effect measurements. Analyses of these results with fast Fourier transform (FFT) lead to fundamental frequencies and effective masses for electrons and holes that are independent of the implantation fluences. The Hall resistivity at low temperatures shows a sign reversal as a function of the field in all implanted states. We interpret the obtained results with basis on a qualitative model that supposes the existence of an extrinsic hole density associated to the defect structure of our sample. We conclude that the As implantation does not produce a semiconductor-type doping in our HOPG sample. Instead, an increase in the extrinsic hole density is likely to occur as a consequence of disorder induced by implantation. [ABSTRACT FROM AUTHOR]

Spintronics has emerged in the last two decades as both an extremely fruitful direction of research into the properties and usefulness of the spin degree of freedom of the electron as it can apply to the exponentially expanding world of electronics. Spintronics has infiltrated almost every household in the form of the read head sensors for the hard drives that inhabit every desktop and most laptop computers. Embedded magnetic random access memory (MRAM) and in-plane STT-RAM are rapidly replacing SRAM in a host of applications that do not require ultra-dense memories. Soon these embedded spintronic memories will permeate the cell phone market because they are much denser than SRAM, offer lower power at only slightly lower speed and are non-volatile. The present work in spintronics at most of the mainstream semiconductor companies and foundaries is focused on the development of perpendicular STT-MRAM, as a universal memory that can compete with the mainstream memories and surpass them in several key metrics. Several innovative ideas are presented where spintronics may have an impact because of the uniqueness of the approach. Nanomagnetic logic and storage may offer extremely high densities at very low power. Spin-torque oscillators are a very novel approach to pattern recognition that may be relevant for handling massive data sets. The spin of the electron may also be on the critical path for quantum computation or communication, another revolutionary change in how we process information. [ABSTRACT FROM PUBLISHER]

We present the relationships between the structure, magnetic properties and high-frequency magnetoresistance (MR) effect in melt-extracted CoFeBSi microwires subject to thermal annealing. In order to release residual stresses to improve the magnetic softness while retaining the good mechanical property of an amorphous material, microwire samples were annealed at different temperatures of 100°C, 200°C, 350°C, 400°C, and 450°C for 15 min. We have shown that relative to an as-cast amorphous microwire, annealing microwires at T = 100°C, 200°C, and 350°C improved both the magnetic softness and the MR effect, while an opposite trend was observed for the microwires annealed at T = 400°C and 450°C. We have observed a distinct difference in the frequency dependence of MR response ( ξ) for dc applied magnetic fields below and above the effective anisotropy field of the microwires. While the microwire annealed at 200°C shows the largest MR ratio (~580%) at 100 MHz, the highest value of ξ (~34%/Oe) has been achieved at 400 MHz for the microwire annealed at 350°C. These results indicate that the optimally annealed CoFeBSi microwires are attractive candidates for high-frequency sensor applications. [ABSTRACT FROM AUTHOR]

In intermetallic compounds RE Co 2 Si 2 ( RE =Pr and Nd), cobalt has been partially substituted by vanadium to obtain RE (Co 1− x V x ) 2 Si 2 ( 0 ≤ x ≤ 0.35 ). The parent compounds are antiferromagnetic below about 30 K due to the ordering of localized magnetic moments that are present only on rare-earth ions, cobalt being non-magnetic in the parent compounds. The present study demonstrates that in these compounds where 3 d and 4 f ions occupy different layers in the crystal structure, V substitution and subsequent lattice expansion results in the occurrence of inequivalent magnetic ions and complex interactions that lead to multiple magnetic transitions. At temperatures around 40–50 K, the temperature dependence of magnetization indicates a ferrimagnetic transition which is accompanied by a rapid decrease in the temperature dependence of resistivity. Below temperatures ∼30 K, the samples begin to show ferromagnetic-like behavior with the appearance of a coercive field and saturation in the magnetization at magnetic fields above ∼2 T. These two magnetic transitions are indicated also by prominent λ -like peaks in specific heat measurements. At around 10 K, a sharp drop in the resistivity indicates another magnetic transition which is followed by a rapid increase in coercive field with decrease in temperature. In a magnetic field of 9 T, the latter transition shifts to a lower temperature and that leads to a positive magnetoresistance. The onset of ferromagnetism at ∼30 K is accompanied with an exchange bias field which is observed for the first time in layered intermetallic compounds. The exchange bias field increases rapidly below the transition at ∼10 K and reaches ∼16% of coercive field at 2 K. [ABSTRACT FROM AUTHOR]

In this study, we showed the crystal structure, electric resistivity, Seebeck and Hall coefficients, magneto-resistance, and magnetic susceptibility of Pr 1 − x Ca x Ba 2 Cu 4 O 8 (x = 0.0, 0.02, and 0.05) are all relevant for our understanding of physical properties along CuO double chains. The lattice parameters of Ca substituted PrBa 2 Cu 4 O 8 remained almost invariant up to x = 0.05. Contrary to the Ca doping effect in the PrBa 2 Cu 3 O 7 − δ system, the significant increases in the Seebeck and Hall coefficients due to the Ca substitution indicate a decrease in the carrier number. The significant magneto-resistance effect in the parent sample (16% at 10 K) was significantly reduced down to 5% in the x = 0.05 composition. On the basis of the two types of carrier models, we discussed the influence of Ca substitution on the electrical transport and magneto-transport properties. • Metallic double chain based Pr/Ca124 compounds with low Ca substitution were successfully synthesized by a citrate pyrolysis method. • Despite Ca2+ replacement for Pr3+, the transport and magneto-transport properties of Pr/Ca124 suggested a significant reduction in the carrier number, which is in contrast with the Pr/Ca123 system. • Assuming that a carrier suppression due to the Ca substitution is attributed to the CuO double chains, our overall data for Pr/Ca124 are well explained based on the two-types of carrier transport model. [ABSTRACT FROM AUTHOR]

The composites with composition of (1− x )La 0.67 Sr 0.33 MnO 3 (LSMO)+( x )Ni 0.5 Zn 0.5 Fe 2 O 4 (NZFO) with x =0.0 (S1), 0.04 (S2), 0.07 (S3), 0.10 (S4), 0.30 (S5) and 1.0 (S6) were synthesized by solid-state reaction route. Structural study using Rietveld refinement of X-ray diffraction (XRD) pattern indicates a rhombohedrally-distorted structure (space group R 3 c ) for LSMO phase while to that NZFO compound crystallizes in cubic structure (space group Fd 3 m ). XRD patterns and microstructural analysis show that LSMO and NZFO phase exists independently in Ni 0.5 Zn 0.5 Fe 2 O 4 doped composites. The transport properties of the compositions x =0.0, x =0.04, and x =0.07 showed that NZFO phase improves the resistivity and shifts the metal–insulator transition temperature T MI towards lower temperature. The magnetoresistance (MR) of composite samples with x =0.04 and x =0.07 decreases monotonously from 200 to 300 K in a magnetic field of 8 T. At lower temperatures (~5 K), a sharp drop of negative MR at low fields ( H <1 T) has been observed followed by a slower varying MR at a comparatively high-field regime ( H >1 T) where MR is almost linear with applied magnetic field. Temperature dependence of resistivity for composites samples with x =0.04 and x =0.07 has been best fitted by small Polaron hopping (SPH) and variable range hopping models (VRH). [ABSTRACT FROM AUTHOR]