Showing papers on "Magnetoresistance published in 2013"
TL;DR: In this article, the classical magnetoresistance of a Weyl metal in which the electron Fermi surface possesses nonzero fluxes of the Berry curvature was considered, and it was shown that such a system may exhibit large negative magnetoreduction with unusual anisotropy as a function of the angle between the electric and magnetic fields.
Abstract: We consider the classical magnetoresistance of a Weyl metal in which the electron Fermi surface possesses nonzero fluxes of the Berry curvature. Such a system may exhibit large negative magnetoresistance with unusual anisotropy as a function of the angle between the electric and magnetic fields. In this case the system can support an additional type of plasma wave. These phenomena are consequences of the chiral anomaly in electron transport theory.
1,148 citations
TL;DR: It is shown that the effect originates from concerted actions of the direct and inverse spin Hall effects and therefore it is called "spin Hall magnetoresistance."
Abstract: We report anisotropic magnetoresistance in Pt|Y3Fe5O12 bilayers. In spite of Y3Fe5O12 being a very good electrical insulator, the resistance of the Pt layer reflects its magnetization direction. The effect persists even when a Cu layer is inserted between Pt and Y3Fe5O12, excluding the contribution of induced equilibrium magnetization at the interface. Instead, we show that the effect originates from concerted actions of the direct and inverse spin Hall effects and therefore call it “spin Hall magnetoresistance.”
927 citations
TL;DR: In this paper, the spin Hall magnetoresistance in multilayers made from an insulating ferromagnet F, such as yttrium iron garnet (YIG), and a normal metal N with spin-orbit interactions was investigated.
Abstract: We present a theory of the spin Hall magnetoresistance (SMR) in multilayers made from an insulating ferromagnet F, such as yttrium iron garnet (YIG), and a normal metal N with spin-orbit interactions, such as platinum (Pt). The SMR is induced by the simultaneous action of spin Hall and inverse spin Hall effects and therefore a nonequilibrium proximity phenomenon. We compute the SMR in F|N and F|N|F layered systems, treating N by spin-diffusion theory with quantum mechanical boundary conditions at the interfaces in terms of the spin-mixing conductance. Our results explain the experimentally observed spin Hall magnetoresistance in N|F bilayers. For F|N|F spin valves we predict an enhanced SMR amplitude when magnetizations are collinear. The SMR and the spin-transfer torques in these trilayers can be controlled by the magnetic configuration.
678 citations
TL;DR: In this article, the spin Hall magnetoresistance effect in ferromagnetic insulator/platinum and non-ferromagnet hybrid structures was investigated and quantitatively analyzed.
Abstract: We experimentally investigate and quantitatively analyze the spin Hall magnetoresistance effect in ferromagnetic insulator/platinum and ferromagnetic insulator/nonferromagnetic metal/platinum hybrid structures. For the ferromagnetic insulator, we use either yttrium iron garnet, nickel ferrite, or magnetite and for the nonferromagnet, copper or gold. The spin Hall magnetoresistance effect is theoretically ascribed to the combined action of spin Hall and inverse spin Hall effect in the platinum metal top layer. It therefore should characteristically depend upon the orientation of the magnetization in the adjacent ferromagnet and prevail even if an additional, nonferromagnetic metal layer is inserted between Pt and the ferromagnet. Our experimental data corroborate these theoretical conjectures. Using the spin Hall magnetoresistance theory to analyze our data, we extract the spin Hall angle and the spin diffusion length in platinum. For a spin-mixing conductance of 4×1014 ??1m?2, we obtain a spin Hall angle of 0.11±0.08 and a spin diffusion length of (1.5±0.5) nm for Pt in our thin-film samples
457 citations
TL;DR: In this paper, proximity-induced ferromagnetism was demonstrated in a topological insulator, combining a ferromagnetic insulator EuS layer with Bi(2)Se(3), without introducing defects.
Abstract: An exchange gap in the Dirac surface states of a topological insulator (TI) is necessary for observing the predicted unique features such as the topological magnetoelectric effect as well as to confine Majorana fermions. We experimentally demonstrate proximity-induced ferromagnetism in a TI, combining a ferromagnetic insulator EuS layer with Bi(2)Se(3), without introducing defects. By magnetic and magnetotransport studies, including anomalous Hall effect and magnetoresistance measurements, we show the emergence of a ferromagnetic phase in TI, a step forward in unveiling their exotic properties.
289 citations
TL;DR: By combining magneto-optical Kerr effect and magnetoresistance measurements, it is shown that domain wall propagation fields can be doubled under locally applied strains, highlighting the prospect of constructing low-power domain wall gates for magnetic logic devices.
Abstract: The control of magnetic order in nanoscale devices underpins many proposals for integrating spintronics concepts into conventional electronics. A key challenge lies in finding an energy-efficient means of control, as power dissipation remains an important factor limiting future miniaturization of integrated circuits. One promising approach involves magnetoelectric coupling in magnetostrictive/piezoelectric systems, where induced strains can bear directly on the magnetic anisotropy. While such processes have been demonstrated in several multiferroic heterostructures, the incorporation of such complex materials into practical geometries has been lacking. Here we demonstrate the possibility of generating sizeable anisotropy changes, through induced strains driven by applied electric fields, in hybrid piezoelectric/spin-valve nanowires. By combining magneto-optical Kerr effect and magnetoresistance measurements, we show that domain wall propagation fields can be doubled under locally applied strains. These results highlight the prospect of constructing low-power domain wall gates for magnetic logic devices.
263 citations
TL;DR: In this article, the spin-Hall magnetoresistance (SMR) in platinum (Pt) on top of yttrium iron garnet (YIG) has been investigated, for both in-plane and out-of-plane applied magnetic fields and for different Pt thicknesses.
Abstract: The occurrence of spin-Hall magnetoresistance (SMR) in platinum (Pt) on top of yttrium iron garnet (YIG) has been investigated, for both in-plane and out-of-plane applied magnetic fields and for different Pt thicknesses [3, 4, 8, and 35 nm]. Our experiments show that the SMR signal directly depends on the in-plane and out-of-plane magnetization directions of the YIG. This confirms the theoretical description, where the SMR occurs due to the interplay of the spin-orbit interaction in the Pt and the spin-mixing conductance at the YIG/Pt interface. Additionally, the sensitivity of the SMR and spin pumping signals on the YIG/Pt interface conditions is shown by comparing two different deposition techniques (e-beam evaporation and dc sputtering).
230 citations
TL;DR: A multilayered semimetal β-CuAgSe with glassy lattice is a new type of promising thermoelectric material suitable for chemical engineering.
Abstract: The electron mobility is one of the key parameters that characterize the charge-carrier transport properties of materials, as exemplified by the quantum Hall effect as well as high-efficiency thermoelectric and solar energy conversions. For thermoelectric applications, introduction of chemical disorder is an important strategy for reducing the phonon-mediated thermal conduction, but is usually accompanied by mobility degradation. Here, we show a multilayered semimetal β-CuAgSe overcoming such a trade-off between disorder and mobility. The polycrystalline ingot shows a giant positive magnetoresistance and Shubnikov de Haas oscillations, indicative of a high-mobility small electron pocket derived from the Ag s-electron band. Ni doping, which introduces chemical and lattice disorder, further enhances the electron mobility up to 90,000 cm(2) V(-1) s(-1) at 10 K, leading not only to a larger magnetoresistance but also a better thermoelectric figure of merit. This Ag-based layered semimetal with a glassy lattice is a new type of promising thermoelectric material suitable for chemical engineering.
174 citations
TL;DR: In this article, the growth mechanisms of VAN thin films have been investigated by varying the composite material system, the ratio of the two constituent phases, and the thin film growth conditions including deposition temperature and oxygen pressure as well as growth rate.
153 citations
TL;DR: A novel organic spin valve device using C(60) as the spacer layer and a large spin-dependent transport length of approximately 110 nm was experimentally observed for the C( 60) layer at room temperature, one of the highest magnetoresistance ratios ever reported.
Abstract: The integration of organic semiconductors and magnetism has been a fascinating topic for fundamental scientific research and future applications in electronics, because organic semiconductors are expected to possess a large spin-dependent transport length based on weak spin-orbit coupling and weak hyperfine interaction. However, to date, this length has typically been limited to several nanometres at room temperature, and a large length has only been observed at low temperatures. Here we report on a novel organic spin valve device using C(60) as the spacer layer. A magnetoresistance ratio of over 5% was observed at room temperature, which is one of the highest magnetoresistance ratios ever reported. Most importantly, a large spin-dependent transport length of approximately 110 nm was experimentally observed for the C(60) layer at room temperature. These results provide insights for further understanding spin transport in organic semiconductors and may strongly advance the development of spin-based organic devices.
147 citations
TL;DR: In this paper, it was shown that the high-field magnetoresistance of Bi2Te2Se is linear in field at low temperatures and low magnetic fields, and the slope of this linear-like MR is nearly independent of temperature over the range T = 7 to 150 K.
Abstract: In addition to the weak antilocalization cusp observed in the magnetoresistance (MR) of topological insulators at low temperatures and low magnetic fields, we find that the high-field MR in Bi2Te2Se is linear in field. At fields up to B = 14 T, the slope of this linear-like MR is nearly independent of temperature over the range T = 7 to 150 K. We find that the linear MR arises from the competition between a logarithmic phase coherence component and a quadratic component. The quantum phase coherence dominates up to high temperatures, where the coherence length remains longer than the mean free path of electrons.
TL;DR: In situ micro-four-point-probe conductivity measurements in ultrahigh vacuum revealed that the Si(111)-striped incommensurate-Pb surface showed the superconductivity transition at 1.1 K.
Abstract: In situ micro-four-point-probe conductivity measurements in ultrahigh vacuum revealed that the Si(111)-striped incommensurate-Pb surface showed the superconductivity transition at 1.1 K. Both of the hexagonal and rectangular phases of Si(111)√[7]×√[3]-In surface showed superconductivity at 2.4 and 2.8 K, respectively. By applying magnetic field perpendicular to the surface, the upper critical field was deduced to be 0.1-1 T. The derived Ginzburg-Landau coherence length of the Cooper pairs was several tens of nm, which was much smaller than the Pippard's coherence length estimated from the band structures. The short coherence length is determined by the carrier mean free path.
TL;DR: In this article, a broadband ferromagnetic resonance approach was used to determine the spin diffusion length in Pd of 5.5 nm and observed a systematic change of the voltage line shape when reversing the stacking order of the F/N bilayer.
Abstract: Voltages generated from inverse spin Hall and anisotropic magnetoresistance effects via spin pumping in ferromagnetic (F)/nonmagnetic (N) bilayers are investigated by means of a broadband ferromagnetic resonance approach. Varying the nonmagnetic layer thickness enables the determination of the spin diffusion length in Pd of 5.5 \ifmmode\pm\else\textpm\fi{} 0.5 nm. We also observe a systematic change of the voltage line shape when reversing the stacking order of the F/N bilayer, which is qualitatively consistent with expectations from spin Hall effects. However, even after independent calibration of the precession angle, systematic quantitative discrepancies in analyzing the data with spin Hall effects remain.
TL;DR: In this paper, the model spinterface between phthalocyanine molecules and a Co single crystal surface was shown to have spintronic properties that can endure well above room temperature.
Abstract: Organic semiconductors constitute promising candidates toward large-scale electronic circuits that are entirely spintronics-driven Toward this goal, tunneling magnetoresistance values above 300% at low temperature suggested the presence of highly spin-polarized device interfaces However, such spinterfaces have not been observed directly, let alone at room temperature Thanks to experiments and theory on the model spinterface between phthalocyanine molecules and a Co single crystal surface, we clearly evidence a highly efficient spinterface Spin-polarised direct and inverse photoemission experiments reveal a high degree of spin polarisation at room temperature at this interface We measured a magnetic moment on the molecule’s nitrogen π orbitals, which substantiates an ab-initio theoretical description of highly spin-polarised charge conduction across the interface due to differing spinterface formation mechanisms in each spin channel We propose, through this example, a recipe to engineer simple organic-inorganic interfaces with remarkable spintronic properties that can endure well above room temperature
TL;DR: Extremely large magnetoresistance is realized in the nonmagnetic layered metal PdCoO(2), and the temperature dependence of the resistance becomes nonmetallic for this field direction, while it remains metallic for fields along the [110] direction.
Abstract: Extremely large magnetoresistance is realized in the nonmagnetic layered metal ${\mathrm{PdCoO}}_{2}$. In spite of a highly conducting metallic behavior with a simple quasi-two-dimensional hexagonal Fermi surface, the interlayer resistance reaches up to 35 000% for the field along the $[1\overline{1}0]$ direction. Furthermore, the temperature dependence of the resistance becomes nonmetallic for this field direction, while it remains metallic for fields along the [110] direction. Such severe and anisotropic destruction of the interlayer coherence by a magnetic field on a simple Fermi surface is ascribable to orbital motion of carriers on the Fermi surface driven by the Lorentz force, but seems to have been largely overlooked until now.
TL;DR: Normalized data of the negative MR almost falls into a single curve and is well fitted by a theoretical equation of the soliton density, meaning that the origin of the MR is ascribed to the magnetic scattering of conduction electrons by a nonlinear, periodic, and countable array of magnetic soliton kinks.
Abstract: We investigate the interlayer magnetoresistance (MR) along the chiral crystallographic axis in the hexagonal chiral magnet CrNb3S6. In a region below the incommensurate-commensurate phase transition between the chiral soliton lattice and the forced ferromagnetic state, a negative MR is obtained in a wide range of temperature, while a small positive MR is found very close to the Curie temperature. Normalized data of the negative MR almost falls into a single curve and is well fitted by a theoretical equation of the soliton density, meaning that the origin of the MR is ascribed to the magnetic scattering of conduction electrons by a nonlinear, periodic, and countable array of magnetic soliton kinks.
TL;DR: In this article, the authors present electrical transport data for single-crystalline Co(2)FeSi, a candidate half-metallic ferromagnet Heusler compound, revealing a textbooklike exponential suppression of the electron-magnon scattering rate with decreasing temperature.
Abstract: Half-metallic ferromagnetism stands for the technologically sought-after metallicity with 100% spin polarization. Electrical transport should, in principle, sensitively probe half-metallic ferromagnetism, since electron-magnon scattering processes are expected to be absent, with clear-cut consequences for the resistivity and the magnetoresistance. Here we present electrical transport data for single-crystalline Co(2)FeSi, a candidate half-metallic ferromagnet Heusler compound. The data reveal a textbooklike exponential suppression of the electron-magnon scattering rate with decreasing temperature which provides strong evidence that this material indeed possesses perfect spin polarization at low temperature. However, the energy scale for thermally activated spin-flip scattering is relatively low (activation gap Δ≈100 K) which has decisive influence on the magnetoresistance and the anomalous Hall effect, which exhibit strong qualitative changes when crossing T≈100 K.
TL;DR: In this article, the spin diffusion length of Pt (? = 1.1±0.3?nm) as well as the real (Gr = (7±3)×1014???1m?2) and imaginary part (Gi = (5± 3)× 1014??? 1m? 2) of the spin-mixing conductance and their ratio (Gr/Gi = 16±4).
Abstract: The effective field torque of an yttrium-iron-garnet (YIG) film on the spin accumulation in an attached platinum (Pt) film is measured by the spin-Hall magnetoresistance (SMR). As a result, the magnetization direction of a ferromagnetic insulating layer can be measured electrically. Experimental transverse and longitudinal resistances are well described by the theoretical model of SMR in terms of the direct and inverse spin-Hall effect, for different Pt thicknesses [3, 4, 8, and 35 nm]. Adopting a spin-Hall angle of Pt ?SH = 0.08, we obtain the spin diffusion length of Pt (? = 1.1±0.3?nm) as well as the real (Gr = (7±3)×1014???1m?2) and imaginary part (Gi = (5±3)×1013???1m?2) of the spin-mixing conductance and their ratio (Gr/Gi = 16±4).
TL;DR: In this paper, the magnetic phase diagram has been constructed in the vicinity of the phase transition and a transition from a paramagnetic to a magnetically ordered phase occurs near 120 K. The transition is found to strongly affect the electrical transport.
Abstract: The chiral helimagnet Cr${}_{1/3}$NbS${}_{2}$ has been investigated by magnetic, transport, and thermal properties measurements on single crystals and by first-principles electronic structure calculations. From the measured field and temperature dependence of the magnetization for fields applied perpendicular to the $c$ axis, the magnetic phase diagram has been constructed in the vicinity of the phase transition. A transition from a paramagnetic to a magnetically ordered phase occurs near 120 K. The transition is found to strongly affect the electrical transport. The resistivity decreases sharply upon cooling near 120 K, and the spin reorientation from the helimagnetic ground state to the commensurate ferromagnetic state is evident in the magnetoresistance. At high fields, a large magnetoresistance ($55%$ at 140 kOe) is observed near the magnetic transition temperature. Heat capacity and electronic structure calculations show that the density of states at the Fermi level is low in the magnetically ordered state.
TL;DR: In this article, the structure, magnetic, and transport properties of thin films of the Heusler ferrimagnet Mn2CoAl have been investigated for properties related to spin gapless semiconductors.
Abstract: The structure, magnetic, and transport properties of thin films of the Heusler ferrimagnet Mn2CoAl have been investigated for properties related to spin gapless semiconductors. Oriented films were grown by molecular beam epitaxy on GaAs substrates and the structure was found to transform from tetragonal to cubic for increasing annealing temperature. The anomalous Hall resistivity is found to be proportional to the square of the longitudinal resistivity and magnetization expected for a topological Berry curvature origin. A delicate balance of the spin-polarized carrier type when coupled with voltage gate-tuning could significantly impact advanced electronic devices.
TL;DR: It is demonstrated that the spin-based particle reactions can be tuned in a blend of organic materials, and microscopic mechanisms are identified using magnetoresistance lineshapes and voltage dependencies as fingerprints.
Abstract: Harnessing the spin degree of freedom in semiconductors is generally a challenging, yet rewarding task. In recent years, the large effect of a small magnetic field on the current in organic semiconductors has puzzled the young field of organic spintronics. Although the microscopic interaction mechanisms between spin-carrying particles in organic materials are well understood nowadays, there is no consensus as to which pairs of spin-carrying particles are actually influencing the current in such a drastic manner. Here we demonstrate that the spin-based particle reactions can be tuned in a blend of organic materials, and microscopic mechanisms are identified using magnetoresistance lineshapes and voltage dependencies as fingerprints. We find that different mechanisms can dominate, depending on the exact materials choice, morphology and operating conditions. Our improved understanding will contribute to the future control of magnetic field effects in organic semiconductors.
TL;DR: The magnetoresistance effect in the molecular systems including small organic molecules, carbon nanotubes, graphene, conductive polymers and their nanocomposites is critically reviewed.
Abstract: In this review, the classification of magnetoresistance effects, the electrical conduction mechanisms without and with magnetic field, and the spintronics are briefly summarized. The magnetoresistance effect in the molecular systems including small organic molecules, carbon nanotubes, graphene, conductive polymers and their nanocomposites is critically reviewed. The four normally used models are elaborated to disclose the mechanisms of organic magnetoresistance (OMAR) in the organic systems. The most current applications of these molecular systems are also summarized. These molecular systems are envisioned to create next-generation spintronic and electronic devices for flexible applications.
TL;DR: Analysis of the SdH data manifests that the high-mobility bulk electron carriers dominate the magnetotransport and are responsible for the observed large linear MR in YPdBi crystals, implying that the Heusler-based topological insulators have superiorities for investigating the novel quantum transport properties and developing the potential applications.
Abstract: We report the observation of a large linear magnetoresistance (MR) and Shubnikov-de Hass (SdH) quantum oscillations in single crystals of YPdBi Heusler topological insulators. Owning to the successfully obtained the high-quality YPdBi single crystals, large non-saturating linear MR of as high as 350% at 5K and over 120% at 300 K under a moderate magnetic field of 7 T is observed. In addition to the large, field-linear MR, the samples exhibit pronounced SdH quantum oscillations at low temperature. Analysis of the SdH data manifests that the high-mobility bulk electron carriers dominate the magnetotransport and are responsible for the observed large linear MR in YPdBi crystals. These findings imply that the Heusler-based topological insulators have superiorities for investigating the novel quantum transport properties and developing the potential applications.
TL;DR: In this article, an infinite magnetoresistance can be produced by tuning the internal exchange field at the FI/S interface, which can be suppressed by an Al(2)O(3) barrier as thin as 0.3 nm.
Abstract: A theoretical prediction by de Gennes suggests that the resistance in a FI/S/FI (where FI is a ferromagnetic insulator, and S is a superconductor) structure will depend on the magnetization direction of the two FI layers. We report a magnetotransport measurement in a EuS/Al/EuS structure, showing that an infinite magnetoresistance can be produced by tuning the internal exchange field at the FI/S interface. This proximity effect at the interface can be suppressed by an Al(2)O(3) barrier as thin as 0.3 nm, showing the extreme confinement of the interaction to the interface giving rise to the demonstrated phenomena.
TL;DR: In this paper, the authors reported large magnetoresistance (MR) output in fully epitaxial Co2Fe(Ge.5Ga0.5) current-perpendicular-to-plane pseudo spin valves.
Abstract: We report large magnetoresistance (MR) output in fully epitaxial Co2Fe(Ge0.5Ga0.5)/Ag/Co2Fe(Ge0.5Ga0.5) current-perpendicular-to-plane pseudo spin valves. The resistance-area product change (ΔRA) of 12 mΩμm2 at room temperature (RT), equivalent to MR ratio of 57%, and ΔRA = 33 mΩμm2 at 10 K, equivalent to MR ratio of 183%, were obtained by using L21-ordered Co2Fe(Ge0.5Ga0.5) ferromagnetic electrodes. The bulk spin scattering asymmetry (β) were estimated to be ∼0.83 at RT and ∼0.93 at 10 K for the L21-ordered Co2Fe(Ge0.5Ga0.5) films by the Valet-Fert model, indicating that the L21-ordered Co2FeGe0.5Ga0.5 Heusler alloy is virtually half-metal at 10 K, but its half-metallicity is degraded at RT.
TL;DR: In this paper, a voltage-induced perpendicular magnetic anisotropy (PMA) change in sputter-deposited Ta|CoFeB|MgO and Ru|CoEb|mgO junctions was quantitatively evaluated by the field dependence of the tunneling magnetoresistance for various bias voltages.
Abstract: We report a voltage-induced perpendicular magnetic anisotropy (PMA) change in sputter-deposited Ta|CoFeB|MgO and Ru|CoFeB|MgO junctions. The PMA change is quantitatively evaluated by the field dependence of the tunneling magnetoresistance for various bias voltages. We find that both the sign and amplitude of the voltage effect depend on the underlayer, Ta or Ru, below the CoFeB layer. The rf voltage-induced ferromagnetic resonance spectra also support the underlayer-material-dependent direction of the voltage torque. The present study shows that the underlayer is one of the key parameters for controlling the voltage effect.
TL;DR: In this paper, electrical spin injection from a ferromagnet to a bilayer graphene (BLG) through a monolayer (ML) of single-crystal hexagonal boron nitride (h-BN) was demonstrated.
Abstract: We demonstrate electrical spin injection from a ferromagnet to a bilayer graphene (BLG) through a monolayer (ML) of single-crystal hexagonal boron nitride (h-BN). A Ni81Fe19/ML h-BN/BLG/h-BN structure is fabricated using a micromechanical cleavage and dry transfer technique. The transport properties across the ML h-BN layer exhibit tunnel barrier characteristics. Spin injection into BLG has been detected through non local magnetoresistance measurements.
TL;DR: In this article, a comparison between the theoretical results and the PNR and magnetometry data shows that finite-size effects confine the wavelength and lead to a quantization of the number of turns in the helicoid.
Abstract: Magnetoresistance (MR), polarized neutron reflectometry (PNR), and magnetometry measurements in MnSi thin films and rigorous analytical solutions of the micromagnetic equations show that the field-induced unwinding of confined helicoids occurs via discrete steps. A comparison between the theoretical results and the PNR and magnetometry data shows that finite-size effects confine the wavelength and lead to a quantization of the number of turns in the helicoid. We demonstrate that the magnetic state of these finite helicoids can be read by electrical means.
TL;DR: In this article, the magnetotransport properties of individual Bi2Se3 nanoplates were investigated and it was shown that the linear magnetoresistance originates from a two-dimensional transport.
Abstract: We report the magnetotransport properties of individual Bi2Se3 nanoplates. The carrier Hall mobility is up to 104 cm2/Vs. A large positive linear magnetoresistance (MR) approaching to 400% without sign of saturation was observed at 14 T. By angular dependence measurements, we demonstrate that the linear MR originates from a two-dimensional transport. Furthermore, by comparing the Hall mobility and longitudinal resistance under different temperatures, we give very clear evidence that reveals the close relationship between magnetoresistance and mobility.
TL;DR: By using nonequilibrium Green's functions in combination with the density functional theory, the authors investigated the spin transport properties of manganese porphyrin-based spintronic devices.
Abstract: By using nonequilibrium Green's functions in combination with the density functional theory, we investigate the spin transport properties of manganese porphyrin-based spintronic devices constructed by two manganese porphyrin molecules connected with a p-phenylene-ethynylene group. The interesting spin filtering and magnetoresistance effects can be observed in the device. Particularly, when the overlap of π channels between manganese porphyrin and phenyl ring parts is broken, the spin filtering efficiency and magnetoresistance ratio of the device can be effectively increased. Meanwhile, the transition from a giant magnetoresistance molecular device to a tunnelling magnetoresistance molecular device can also be realized by this simple operation process. Moreover, electrically induced switching behavior based on negative differential resistance effects is also observed in our model. The mechanisms are proposed for these phenomena.