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This study investigates the structural, mechanical, electronic, magnetic, and thermoelectric properties of ZrMnX (X = As, Sb, Te) half Heusler alloys using spin‐polarized density functional theory (SPDFT) with WIEN2K code using full potential linearized augmented plane wave(FP‐ LAPW) technique. Results indicate the ferromagnetic phase's stability over the non‐magnetic phase in all three alloys. Band structures and density of states highlight the half‐metallic nature of ZrMnX. These alloys exhibit mechanical stability, ductility, and directional properties. Magnetic moments align with the Slater–Pauling rule. Thermoelectric properties, including Seebeck coefficient, electrical and thermal conductivity, and thermoelectric figure of merit, are evaluated using semi‐classical Boltzmann theory. The Seebeck coefficient values for ZrMnX (X = As, Sb, Te) are 144.7, 123.3, and −182.6 µV K−1, respectively at 1200 K with corresponding highest figure of merit 1.0, 0.7, and 1.78. These findings suggest the suitability of these alloys for spintronic devices and high‐temperature thermoelectric applications due to their observed spin‐polarized character and high figure of merit. [ABSTRACT FROM AUTHOR]

Half‐metallic materials are theoretically predicted to be metallic and insulating, which have not been confirmed experimentally, and the predictions are still in doubt. We report the resistance‐chiral anisotropy (R‐ChA), i.e. chirality‐dependent electrical conductivity, in chiral mesostructured Fe3O4 films (CMFFs) grown on the substrates via a hydrothermal method using amino acids as symmetry‐breaking agents. Two levels of chirality exist in the CMFFs: primary distortion of the crystal lattice forms twisted nanoflakes, and secondary helical stacking of nanoflakes forms fan‐shaped nanoplates. At temperatures below 30 K, the CMFFs exhibited metallic conductivity and insulation for one handedness and the other, respectively. The chirality‐dependent effective magnetic fields were speculated to stabilize the opposite spin in the antipodal chiral frame, which led to the free transport of electrons in one handedness of the chiral structure and immobility for the other handedness. [ABSTRACT FROM AUTHOR]

In the present work we have performed self-consistent ab-initio calculation using the full-potential linearized augmented plane-wave method (FP-LAPW), based on the density functional theory (DFT) as implemented in the Wien2k code to study the structural, electronic, magnetic, thermodynamic and thermoelectric properties of the half-heusler compound CrYSn (Y = Ca , Sr) using generalized gradient approximation (GGA) described by Perdew–Burke–Ernzerhof (PBE), GGA+U and the modified Beck–Johnson correction (mBJ), the obtained results show that the compound is stable in the ferromagnetic state (FM) in α phase on one hand and has a half-metallic character (metallic nature in spin up channel and semiconductor one in spin down channel with an indirect gap) on the other hand thus, the compound is a good candidate for spintronic applications, moreover it shows a very interesting thermoelectric predisposition in the minority spin or spin down channel at room temperature consisting of a very high Seebeck coefficient, high electrical conductivity and figure of merit near unity for the two compounds. The thermodynamic properties of CrCaSn and CrSrSn compounds using Gibbs code are studied for the first time. This study showed that these compounds can be used in extreme thermodynamic conditions. Since no experimental data were reported until now concerning this compound, our theoretical predictions of electronic, thermodynamic and thermoelectric properties are likely to be experimentally verified. [ABSTRACT FROM AUTHOR]

The spintronic is an emerging technology which controls the properties of multifactional devices with spin of electrons. In present manuscript, Wien2k and Boltz Trap codes are used to explore electronic, magnetic, and thermoelectric characteristics of Sr 2 CrXO 6 (X = Nb, Mo) double perovskites (DPs). The evaluation of energies released in paramagnetic (PM), antiferromagnetic (AFM), and ferromagnetic (FM) states assure the stability of FM states. Both the negative formation energy and the tolerance factor confirm structural and thermodynamic stability in FM states. The 100 % spin polarization was confirmed by both integer values of magnetic moment (MM) and the spin polarization factor. The values of exchange energy, double exchange model, hybridization of p-d states, and exchange constants are calculated to explore the nature of ferromagnetism and spin functionality. The effect of thermoelectric parameters on spin of electrons and thermoelectric performance are elaborated by thermal to electrical conductivity ratio, Seebeck coefficient and power factor. • High Curie temperature, and spintronic applications. • Spin of electrons overcome the charge with multifuctional properties. • Double exchange mechanism confirms the ferromagnetism by electron spin instead of magnetic ion clustering. • Half metallic ferromagnetism and 100 % spin polarization. • Large value of electrical conductivity and low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

We study the spin-dependent tunneling time, including group delay and dwell time, in a graphene based asymmetrical barrier with Rashba spin–orbit interaction in the presence of strain, sandwiched between two normal leads. We find that the spin-dependent tunneling time can be efficiently tuned by the barrier width, and the bias voltage. Moreover, for the zigzag direction strain although the oscillation period of the dwell time does not change, the oscillation amplitude increases by increasing the incident electron angle. It is found that for the armchair direction strain unlike the zigzag direction the group delay time at the normal incidence depends on the spin state of electrons and Hartman effect can be observed. In addition, for the armchair direction strain the spin polarization increases with increasing the RSOI strength and the bias voltage. The magnitude and sign of spin polarization can be manipulated by strain. In particular, by applying an external electric field the efficiency of the spin polarization is improved significantly in strained graphene, and a fully spin-polarized current is generated. [ABSTRACT FROM AUTHOR]

Coherent spin transport in metallothioneins connected to gold electrodes has been calculated to examine the behavior of the molecule toward spin flow (radicals) in the body. The spin polarization appears to derive considerable spin filtering. Spin polarization localized on the sulfur atoms of cadmium-thiolate clusters. [Display omitted] • Non-equilibrium state of electron/spin transport in metallothionein. • Coherent spin transport in metallothionein connected to metal electrodes. • Cysteine scavenging free radicals even when forming the cadmium-thiolate cluster. Metallothioneins (MTs) play an important role in controlling the concentration of heavy metals in the body by forming metal-thiolate clusters. In addition, the proteins can scavenge free radicals, to exhibit an antioxidant effect. To clarify the precise physiological function of these proteins, it is necessary to examine the non-equilibrium state of electron/spin transport in the molecule. In this study, coherent spin transport in MTs connected to metal electrodes has been calculated to examine the behavior of the molecule toward spin flow (radicals) in the body. The estimated values of conductance were found to be very low, while the spin polarization appears to derive considerable spin filtering. Furthermore, spin polarization did not localize on cadmium but on the sulfur atoms of cadmium-thiolate clusters. These results confirmed that cysteine plays an important role in the scavenging of free radicals even when forming the cadmium-thiolate cluster. Significance Statement. The purpose of this study is to better understand how spin polarization (induced radical) flows in metallothionein, even if it forms cadmium-thiolate clusters. This is important because it can be known where the radical is stored and processed in the body. Our results provide a guide to examine non-equilibrium electron transient in the metallothionein by observing the single-molecule electric conduction with scanning tunneling microscope. [ABSTRACT FROM AUTHOR]

Harvesting waste heat back into electricity by exploiting the temperature difference across two ends of a nanodevice and its concomitant spin dependence has led to the emergence of a new field known as spin caloritronics. Herein, we report the spin polarized thermoelectric features in a π-stacked system comprised of (C n -C 6 H 6 –Fe–C 6 H 6 –C 13-n) n = 2. A decisive factor, the Seebeck coefficient, becomes fully spin dependent on temperature and switches from positive to negative values, which illustrates the switching of the thermoelectric behavior from a p-to n-type due to the change in the spin state from spin-down to spin-up. A relatively large thermoelectric figure of merit has been reported in the case of the spin figure of merit of the system. In this context, three major observations have been made: i) The Seebeck coefficient has a distinctive feature over two different spin channels, ii) the spin Seebeck coefficient (S s) is nearly four times larger than the charge Seebeck coefficient (S c), and (iii) the spin thermoelectric figure of merit (Z S) rises by 80% with respect to charge thermoelectric figure of merit (Z C) under thermal bias. Our results have been well explained through the analysis of temperature dependent transmission spectra of the system. The emergence of a relatively large spin Seebeck coefficient allows us to measure the pure spin current of the system as well as extending the devices application from simple memory (MRAM) devices to on-chip energy harvesting systems. Variation in the spin and charge thermoelectric figure of merit and spin dependent Seebeck coefficient with thermal bias. [Display omitted] • A clean and green energy solution to the massive waste heat generated in a circuit is thermoelectric materials. • Modification in thermoelectric feature against the spin polarization of tunneling electron has developed a new but virgin domain of Spincaloritronics. • Thermoelectric features are analysed mainly through ZT, spin polarized electrical conductivity, spin polarized Seebeck coefficient, In Spincaloritronics, one would have separate figure of merit for charged part and spin part as well as separate charge and spin Seebeck coefficient. • On an average Spin Seebeck coefficient (S s) is approximately four times larger than its charge counterpart (S c) and there is nearly 80% rise in Z S from Z C. Most, significant observation is switching in thermospin behavior from n to p type due to spin reversal. • Dissimilar behavior over two different spin channels certainly exemplify the appearance of spin dependent Seebeck effect with switching action from p to n type due to spin reversal. [ABSTRACT FROM AUTHOR]

Herein, we propose and provide evidence for the experimentally and theoretically promising route of exploring spintronics materials with high performance via a synthetic hybrid of half-metallic ferromagnet and diluted magnetic semiconductor. Crystalline and well-ordered [Co2FeGe/Ge(Mn)]n superlattice, which is free of secondary phase separation, were prepared by the hybridization of end members, Co2FeGe and Ge(Mn), using the molecular beam epitaxy technique. Besides comparable magnetic properties with respect to the Co2FeGe films, the superlattice sample exhibits superior properties in electric conductivity and spin polarization, thus enhancing in favor of the spin injection efficiency. These results demonstrate the high feasibility of spintronics materials with low saturation magnetization, small coercivity, high Curie temperature, and high spin injection efficiency through the proposed route in this work. [ABSTRACT FROM AUTHOR]

We evaluate the spin polarization (Edelstein or inverse spin galvanic effect) and the spin Hall current induced by an applied electric field by including the weak localization corrections for a two-dimensional electron gas. We show that the weak localization effects yield logarithmic corrections to both the spin polarization conductivity relating the spin polarization and the electric field and to the spin Hall angle relating the spin and charge currents. The renormalization of both the spin polarization conductivity and the spin Hall angle combine to produce a zero correction to the total spin Hall conductivity as required by an exact identity. Suggestions for the experimental observation of the effect are given. [ABSTRACT FROM AUTHOR]

• Double impurities (Fe, Mn) co-doped SnSe 2 preferred ferromagnetic couplings. • The through bond spin polarization mechanism was proposed as the origin of ferromagnetic. • The strain can regulate the ferromagnetism and optics of (Fe, Mn) co-doped SnSe 2 system. • The Optical properties of (Fe, Mn) co-doped SnSe 2 system has been researched. • Magnetism and Optical properties are linked by orbital analysis. The magnetic and optical properties for double impurities (Fe, Mn) doped SnSe 2 are investigated by first principles calculations. We calculate that the magnetic moments of Fe and Mn for Fe and Mn mono-doped SnSe 2 are 3.98 μ B and 4.97 μ B , respectively. In the GGA + U method, the ferromagnetism of the (Fe, Mn) co-doped SnSe 2 system prefers the most stable state, which is resulted from the hybridization between Fe:3d, Mn:3d and Se:4p states. In addition, we apply strain to research the magnetism for the (Fe, Mn) co-doped SnSe 2 system in the GGA + U method. We find that the structure of molecule are changed by strain and the ferromagnetism of (Fe, Mn) co-doped SnSe 2 is also significantly improved. The introduction of transition metal (TM = Fe, Mn) can effectively improve electric conductivity. And the adsorption strength of TM doped SnSe 2 is also outstanding enhanced. The deficiency of ultra violet absorption in the doped system is compensated under strain. These results indicate the (Fe, Mn) co-doped SnSe 2 will be a perfect candidate for spintronic devices applications. [ABSTRACT FROM AUTHOR]

(Bi1/2Na1/2)(Mn1/2Nb1/2)O3(BNMNO) ceramics were sintered at ambient air. XRD test exhibited coexistence of phases. The permittivity and conductance were measured at radio frequencies. Activation energy values were estimated as 0.38 eV. Electronic structure was simulated for BNMNO and also for BiMnO3(BMO) as the reference. Theab initiocalculations were performed within DFT using LCAO with localized basis set in the form of spherical functions as implemented in the SIESTA 3.0 code together with a spin polarization. An energy gap was estimated for the ideal BMO and BNMNO lattice to be 0.8 eV and 0.4 eV, respectively. An oxygen vacancy and an interstitial oxygen introduced to calculation caused narrowing the gap. [ABSTRACT FROM PUBLISHER]

In the present work, theoretical investigations of structural, electronic, magnetic, and thermoelectric properties of Cd 0.875 TM 0.125 O (TM = Mn, Fe, Co, Ni) half-metallic ferromagnets are done using WIEN2K code. The computed results when compared with the reported theoretical works reveal consistency. The band structures for spin up (↑), and spin down (↓) channels reveal the half metallic (Mn, Co, Fe), and frustrated (Ni) magnetism. The nature of magnetism has been analyzed in terms of hybridization among 3d states of TMs, individual Cd (5s, 4d) states, and O (2p) states. The control and function of the electron spin are revealed by calculating exchange energies (Δ x (d), Δ x (pd)), crystal field energy (ΔE cryst) and exchange constant (N o α, N o β), those play a very crucial role in understanding the magnetic nature. Moreover, double exchange and RKKY models are discussed to justify the observed half-metallic, and metallic behaviors, which are responsible for the magnetic moments to stabilize a magnetic polarization. The influence of electron spin is explained using the computed electrical and thermal conductivities, while thermoelectric power is elaborated by computing Seebeck coefficient and power factor. • Above room temperature ferromagnetism, and spintronic applications •Quantum spin of electrons dominant the charge with multifuctional properties •Exchange mechanism certifies the ferromagnetism by electron spin instead of magnetic ion clustering •Half metallic ferromagnetism and 100% spin polarization •Large value of electrical conductivity and ultralow low values of thermal conductivity. [ABSTRACT FROM AUTHOR]

We have performed conductivity measurements on a Si-MOSFET sample with a slot in the upper gate, allowing for different electron densities n1 and n2 across the slot. Dynamic longitudinal resistance was measured by a standard lock-in technique, while maintaining a large dc current through the source-drain channel. We find that in a parallel magnetic field, the resistance of the sample R(Idc) is asymmetric with respect to the direction of the dc current. The asymmetry becomes stronger with an increase of either the magnetic field or the difference between n1 and n2. These observations are interpreted in terms of the effective spin injection: the degree of spin polarization is different in the two parts of the sample, implying different magnitudes of spin current away from the slot. The carriers thus leave the excess spin (of the appropriate sign) in the region around the slot, leading to spin accumulation (or depletion) and to the spin-drift-diffusion phenomena. Due to the positive magnetoresistance of the two-dimensional electron gas, this change in a local magnetization affects the resistivity near the slot and the measured net resistance, giving rise to an asymmetric contribution. We further observe that the value of R(Idc) saturates at large Idc; we suggest that this is due to electron tunneling from the two-dimensional n-type layer into the p-type silicon (or into another "spin reservoir") at the slot. [ABSTRACT FROM AUTHOR]

Electron spin polarization properties of the Datta-Das spin field effect transistors are studied by taking into account the coexistence of the Rashba and Dresselhaus effects and an in-plane magnetic field. The transistor is connected to ferromagnetic leads with unparallel polarization. Transmission coefficients can be calculated and thus the Landauer-Büttiker conductance are obtained. Numerical results for the spin polarization of the conductance were discussed in detail. [ABSTRACT FROM AUTHOR]

The spin-dependent electron transport is theoretically investigated in a two-dimensional electron gas, which is periodically modulated by ferromagnetic and Schottky metal (SM) stripes. We find that the spin-dependent transmission and conductance as well as polarization strongly depend on the number of periods. We also find that the transmission and the polarization of transmitted beams periodically change with increasing the width of the SM stripe. [ABSTRACT FROM AUTHOR]

Abstract: Spin injection in an organic semiconductor system under an external electric-field was studied theoretically by considering spin-dependent conductivity. The effect of the spin-dependent electrical-conductivity on the spin-injection efficiency is self-consistently derived. It is found that the spin-injection efficiency depends evidently on the spin-dependent electrical-conductivity. When the spin-injection efficiency increases 20%, the spin-dependent electrical-conductivity increases nearly four orders of magnitude at T = 10 K. With the increase of external electric-field, the spin-dependent electrical-conductivity increases sharply and makes the spin-injection efficiency increase, too. When the external electric-field varies from 1 to 10 mv/μm, the spin-injection efficiency increases almost 10% at room temperature. It seems to be significant to consider the spin-dependent electrical-conductivity under the external electric-field in spin-injected organic system. [ABSTRACT FROM AUTHOR]

Abstract: Spin injection across ferromagnet/organic semiconductor system with finite width of the layers was studied theoretically considering spin-dependent conductivity in the organic-semiconductor. It was found that the spin injection efficiency is directly dependent on the difference between the conductivity of the up-spin and down-spin polarons in the spin-injected organic system. Furthermore, the finite width of the structure, interfacial electrochemical-potential and conductivity mismatch have great influence on the spin injection process across ferromagnet/organic semiconductor interface. [Copyright &y& Elsevier]

Abstract: We present a theoretical study on the spin-dependent electron transport in a two-dimensional electron gas (2DEG) modulated by a stripe of magnetized ferromagnetic metal under an applied voltage. It is shown that highly spin-polarized current can be achieved in this kind of nanosystems. It is also shown that the spin polarity of the electron transport can be switched by adjusting the applied voltage to the stripe in the device. These interesting properties may provide an alternative scheme to spin-polarize electrons into semiconductors, and this device may be used as a voltage-tunable spin-filter. [Copyright &y& Elsevier]

Abstract: The electrical properties and magnetoresistance (MR) of CrO2/Fe3O4 composites with opposite spin polarization have been investigated as a function of CrO2 content. Experimental results indicate that the conductivity exhibits an abrupt increase when CrO2 volume fraction ϕ is close to 0.15, where a percolation behavior happens. Magnetoresistance measurement shows a minimum value in the vicinity of percolation threshold at a temperature of 77 K, while this phenomenon cannot be observed at 150 K. Due to spin-dependent tunneling through grain boundary, the reduction in MR at 77 K mainly results from the opposite sign of spin polarizations in the binary half-metal granular CrO2/Fe3O4 composite. [Copyright &y& Elsevier]

Abstract: We present a theoretical study on spin-dependent transport of electrons in any anti-parallel double -magnetic-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the surface of a semiconductor heterostructure. A general fomula of tranmission probability for electrons tunneling through this kind of nanostructures, is obtained. It is shown that large spin-polarized current can be achieved in such a device. It also is shown that the degree of electron-spin polarization is strongly dependent upon magnetic-strength difference of two -barriers. These interesting properties may provide an alternative scheme to spin-polarize electrons into semiconductors, and this device may be used as a tunable spin-filter. [Copyright &y& Elsevier]

Abstract: We have investigated a series of double-layer structures consisting of a layer of self-assembled non-magnetic CdSe quantum dots (QDs) separated by a thin ZnSe barrier from a ZnCdMnSe diluted magnetic semiconductor (DMSs) quantum well (QW). In the series, the thickness of the ZnSe barrier ranged between 12 and 40nm. We observe two clearly defined photoluminescence (PL) peaks in all samples, corresponding to the CdSe QDs and the ZnCdMnSe QW, respectively. The PL intensity of the QW peak is observed to decrease systematically relative to the QD peak as the thickness of the ZnSe barrier decreases, indicating a corresponding increase in carrier tunneling from the QW to the QDs. Furthermore, polarization-selective PL measurements reveal that the degree of polarization of the PL emitted by the CdSe QDs increases with decreasing thickness of the ZnSe barriers. The observed behavior is discussed in terms of anti-parallel spin interaction between carriers localized in the non-magnetic QDs and in the magnetic QWs. [Copyright &y& Elsevier]

We study the magnetization and the magnetic phases of II-VI-based n-doped nonmagnetic- semiconductor (NMS) / narrow to wide dilute-magnetic-semiconductor (DMS) / n-doped NMS quantum wells under in-plane magnetic field. The parallel magnetic field is used as a tool, in order to achieve non-step-like density of states in these -appropriate for conduction-band spintronics- structures. [ABSTRACT FROM AUTHOR]

The structural, electronic, magnetic, elastic and thermoelectric properties of full-Heusler alloys Co 2 ZrZ (Z = Al, Si, Ga and Sn) are investigated using the augmented plane wave method (FP-LAPW) based on the framework of spin density functional theory. The term of the exchange and correlation potential (XC), is treated by the generalized gradient approximation GGA and Trans-Blaha-modified Becke–Johnson (TB-mBJ). The results obtained showed that the Cu 2 MnAl-type structure has more stable energy than the Hg 2 CuTi-type structure for all the full-Heusler studied. From electronic calculations, it is found that all the compounds studied have an indirect band gap with a half-metallic behavior. Furthermore, we also found that all materials have integral magnetic moments which are mainly due to 100% spin polarization at Fermi energy. The calculated elastic constants and the anisotropy shear factors indicate that these compounds have a ductile character and are mechanically stable. Finally, we calculated the thermoelectric properties by applying Boltzmann theory as implemented in the BoltzTraP code. The results obtained for the merit factor (ZT) and Seebeck coefficient (S) make these materials promising candidates in thermoelectric applications and in spintronics devices. • Investigation of optoelectronic and thermoelectric properties for CO 2 ZrZ (Z = Al, Si, Ga and Sn) using Wien2k code. • Heusler alloys with indirect band gap and a half-metallic behavior. • The studied compounds have a ductile character and stable mechanically. • High electrical conductivity and a figure of merit which is close to unity at low temperatures. • They can be considered as a source of low-temperature energy to produce electricity. [ABSTRACT FROM AUTHOR]

One-dimensional (1D) oxalate-bridged homometallic {[Mn(bpy)(C2O4)]·1.5H2O}n (1) (bpy = 2,2'-bipyridine) and heterodimetallic {[CrCu3(bpy)3(CH3OH)(H2O)(C2O4)4][Cu(bpy)Cr(C2O4)3]·CH2Cl2·CH3OH·H2O}n (2) coordination polymers, as well as the three-dimensional (3D) heterotrimetallic {[CaCr2Cu2(phen)4(C2O4)6]·4CH3CN·2H2O}n (3) (1,10-phenanthroline) network, have been synthesized by a building block approach using a layering technique, and characterized by single-crystal X-ray diffraction, infrared (IR) and impedance spectroscopies and magnetization measurements. During the crystallization process partial decomposition of the tris(oxalato)chromate(III) happened and 1D polymers 1 and 2 were formed. The antiferromagnetic interactions between the manganese(II) ions were mediated by oxalate ligands in the chain [Mn(bpy)(C2O4)]n of 1, with intra-chain super-exchange interaction = (−3.134 ± 0.004) K; magnetic interaction between neighbouring chains is negligible making this system closer than other known Mn-chains to the ideal 1D Heisenberg antiferromagnet. Compound 2 comprises a 1D coordination anion [Cu(bpy)Cr(C2O4)3]nn− (Cr2–Cu4) with alternating [Cr(C2O4)3]3− and [Cu(bpy)]2+ units mutually bridged through the oxalate group. Another chain (Cr1–Cu3) is similar, but involves a homodinuclear unit [Cu(bpy)(H2O)(µ-C2O4)Cu(bpy)(CH3OH)]2+ (Cu1–Cu2) coordinated as a pendant group to a terminal oxalate oxygen. Magnetic measurements showed that the Cu1−Cu2 cationic unit is a strongly coupled antiferromagnetic dimer, independent from the other magnetic ions within ferromagnetic chains Cr1–Cu3 and Cr2–Cu4. A 3D polymer {[CaCr2Cu2(phen)4(C2O4)6]·4CH3CN·2H2O}n (3) comprising three different metal centers (Ca2+, Cr3+ and Cu2+) oxalate-bridged, contains Ca2+ atoms as nodes connected with four Cr3+ atoms through oxalate ligands. The network thus formed can be reduced to an underlying graph of diamondoid (dia) or (66) topology. Magnetization of 3 shows the ferromagnetic oxalate-bridged dimers [CuIICrIII], whose mutual interaction could possibly originate through the spin polarization of Ca2+ orbitals. Compounds 1 and 3 exhibit lower electrical conductivity at room temperature (RT) in comparison to compound 2. [ABSTRACT FROM AUTHOR]

Abstract: Using the transfer matrix method, the transmission probability, the spin polarization and the conductance of the ballistic electron are studied in detail in a nanostructure with the periodic applied bias and magnetic barriers. We find that these observable quantities sensitively depend on the number of the periodic magnetic–electric barriers. With the number of the periods increasing, the resonance peaks shift towards right and the number of the resonance peaks is increasing as well as the spin polarization being enhanced. These interesting properties may be helpful for making the bias-tunable spin filter. [Copyright &y& Elsevier]

Abstract: Due to the competition between spatial and magnetic confinement, the density of states (DOS) of a quasi-two-dimensional system deviates from the ideal step-like form both quantitatively and qualitatively. We study how this affects the spin-subband populations and the spin polarization as functions of the temperature, T, and the in-plane magnetic field, B, for narrow to wide dilute-magnetic-semiconductor quantum wells (QWs). We focus on the QW width, the magnitude of the spin–spin exchange interaction, and the sheet carrier concentration dependence. We look for ranges where the system is completely spin polarized. Increasing T, the carrier spin splitting, , decreases, while on increasing B, increases. Moreover, due to the DOS modification, all energetically higher subbands become gradually depopulated. [Copyright &y& Elsevier]

The simultaneous existence of magnetic order and semiconducting nature in ferromagnetic semiconductors fascinate the spintronics technology to enhance the quantum computing and spin transistors. Therefore, electrons spin dependent ferromagnetism and thermoelectric properties of MgCr 2 X 4 (X ​= ​S, Se) spinels are scrutinized by density functional theory (DFT) based Wien2k code. The negative formation energy ensures thermodynamic stability. The band structures (BS) and density of states (DOS) ensure the ferromagnetic semiconductors nature of the studied spinel's. The insulating behavior in down spin and magnetic moment (Integer value) is the response of 100% spin polarization. The fulfillment of the condition Δ (d) > (Δ C F) and negative Δ (p d) have showed the dominant role of electrons spin to induce ferromagnetism. Moreover, influence of electrons spin on thermodynamic and thermoelectric characteristics are explored by specific heat capacity (C v), electrical conductivity (σ/τ), thermal conductivity ((κ/τ)), Seebeck coefficient (S) and power factor (σS2) by classical Boltzmann transport theory. The Ferromagnetic Semiconducting behavior of MgCr 2 X 4 (X ​= ​S, Se) in which up spin channel is semiconducting and down spin channel is insulating. Image 1 • The MgCr 2 X 4 (X ​= ​S, Se) spinels are ferromagnetic semiconductors with 100% spin polarization. • The exchange energies are exactly according to double exchange mechanism. • The above room temperature ferromagnetism enhance the potential for spintronics. • The thermal conductivity and electrical conductivity ratio is of the order of 10−5. [ABSTRACT FROM AUTHOR]

Band strucutre (BS) plots (a) Ca 0.75 Ti 0.25 S and (b) Ca 0.75 Ti 0.25 Se calcuated by using mBJ potnetial. • The Ca 0.75 Ti 0.25 S and Ca 0.75 Ti 0.25 Se are half metallic ferromagnetism with 100% spin polarization. • The exchange energies are exactly according to double exchange mechanism. • The above room temperature ferromagnetism enhance the potential for spintronics. • The thermal conductivity and electrical conductivity ratio is of the order of 10−4. The electronic, magnetic and thermoelectric properties of Ca 0.75 Ti 0.25 S and Ca 0.75 Ti 0.25 Se alloys are explored comprehensively. The stabilityin ferromagnetic state (FM) has been ensured by energy released from optimized structures and enthalpy of formation (ΔH). The Heisenberg classical model has been used to calculate Curie temperature (T c). The band structures (BS) as well as densities of states (DOS) are analyzed to explore half metallic ferromagnetism and 100% spin polarization. The Δ x (d) (exchange energy) overcome ΔE crystal (Crystal field energy) due to ferromagnetism induced by strong hybridization. The negative values of Δ x (pd) and exchange constant N 0 β lesser exchange energy which satisfy the double exchange model. The thermoelectric properties of the studied compounds are elaborated in terms of electrical conductivity, thermal conductivity and Seebeck coefficient. The increase in power factor with the replacement of S by Se has been noted. [ABSTRACT FROM AUTHOR]

We performed first-principles calculations to investigate the formation energy, geometry structure, and electronic property of Fe-doped Bi2Ti2O7 systems with different Fe doping content. The calculated formation energies indicate that the substitutional configurations of Fe-doping Bi2Ti2O7 are easy to obtain under O-rich growth condition, but their thermodynamic stability decreases with the increase of Fe content. The calculated spin-resolved density of states and band structures indicate that the introduction of Fe into Bi2Ti2O7 brings high spin polarization. The spin-down impurity levels in FexBi2−xTi2O7 and spin-up impurity levels in FexBi2Ti2−xO7 systems locate in the bottom of conduction band and narrow the band gap significantly, thus leading to the absorption of visible light. Interestingly, the impurity states in FexBi2−xTi2O7 are the efficient separation center of photogenerated electron and hole, and less affected by Fe doping content, in comparison, the levels of impurity band in FexBi2Ti2−xO7 systems are largely effected by the Fe doping content, and high Fe doping content is the key factor to improve the separating rate of photogenerated electron and hole. [ABSTRACT FROM AUTHOR]

Gate-tunable spin-resolved scattering through a Rashba spin–orbit (SO) coupling graphene barrier is considered theoretically by using a mode-matching method. In this structure, we investigate the dependence of the tunnelling transmission probability on the spin orientation of the incident electron. It is found that the difference of the transmission probability for opposite spin orientations exhibits considerable incident-angle-dependent features when both gate voltage and Rashba SO coupling in the barrier region are present. The difference is adjustable by the gate voltage. More specifically, we find that the sign of spin polarisation of conductance can switch from positive to negative by adjusting the electric potential at any Rashba SO coupling. These results can provide an efficient way to design graphene spintronic devices without the need for ferromagnets. [ABSTRACT FROM AUTHOR]