Showing papers on "Magnetoresistance published in 1998"
TL;DR: The magnetic coupling in all semiconductor ferromagnetic/nonmagnetic layered structures, together with the possibility of spin filtering in RTDs, shows the potential of the present material system for exploring new physics and for developing new functionality toward future electronics.
Abstract: REVIEW Semiconductor devices generally take advantage of the charge of electrons, whereas magnetic materials are used for recording information involving electron spin. To make use of both charge and spin of electrons in semiconductors, a high concentration of magnetic elements can be introduced in nonmagnetic III-V semiconductors currently in use for devices. Low solubility of magnetic elements was overcome by low-temperature nonequilibrium molecular beam epitaxial growth, and ferromagnetic (Ga,Mn)As was realized. Magnetotransport measurements revealed that the magnetic transition temperature can be as high as 110 kelvin. The origin of the ferromagnetic interaction is discussed. Multilayer heterostructures including resonant tunneling diodes (RTDs) have also successfully been fabricated. The magnetic coupling between two ferromagnetic (Ga,Mn)As films separated by a nonmagnetic layer indicated the critical role of the holes in the magnetic coupling. The magnetic coupling in all semiconductor ferromagnetic/nonmagnetic layered structures, together with the possibility of spin filtering in RTDs, shows the potential of the present material system for exploring new physics and for developing new functionality toward future electronics.
4,339 citations
TL;DR: In this paper, an ordered double perovskite (Sr2FeMoO) was shown to exhibit intrinsic tunnelling-type magnetoresistance at room temperature.
Abstract: Colossal magnetoresistance—a huge decrease in resistance in response to a magnetic field—has recently been observed in manganese oxides with perovskite structure. This effect is attracting considerable interest from both fundamental and practical points of view1. In the context of using this effect in practical devices, a noteworthy feature of these materials is the high degree of spin polarization of the charge carriers, caused by the half-metallic nature of these materials20,21; this in principle allows spin-dependent carrier scattering processes, and hence the resistance, to be strongly influenced by low magnetic fields. This type of field control has been demonstrated for charge-carrier scattering at tunnelling junctions2,3 and at crystal-twin or ceramic grain boundaries4,5, although the operating temperature of such structures is still too low (⩽150 K) for most applications. Here we report a material—Sr2FeMoO6, an ordered double perovskite6—exhibiting intrinsic tunnelling-type magnetoresistance at room temperature. We explain the origin of this behaviour with electronic-structure calculations that indicate the material to be half-metallic. Our results show promise for the development of ordered perovskite magnetoresistive devices that are operable at room temperature.
2,065 citations
01 May 1998
TL;DR: A review of the topics of colossal magnetoresistance, charge ordering and related phenomena exhibited by oxides, and contributions covering the present status of the subject can be found in this paper,.
Abstract: An aspect of metal oxides, colossal magnetoresistance exhibited by certain manganese oxides, in particular rare-earth manganates of perovskite structure, has received much attention in recent years. Some of these oxides show 100 per cent magnetoresistance, and have potential for technological applications. This text begins with a review of the topics of colossal magnetoresistance, charge ordering and related phenomena exhibited by oxides, and presents contributions covering the present status of the subject.
1,094 citations
TL;DR: In this paper, a self-consistent Born approximation of the density of states and the conductivity of undoped systems in magnetic fields is proposed, where the quantum theory provides results quite different from the results of Boltzmann transport theory even in the absence of a magnetic field.
Abstract: In a self-consistent Born approximation, the density of states and the conductivity are calculated in a two-dimensional graphite sheet in magnetic fields. Two different cases of scatterers are considered, the short-range case where the range is smaller than the lattice constant and the long-range case where it is comparable or slightly larger. The quantum theory provides results quite different from the results of Boltzmann transport theory even in the absence of a magnetic field. In high magnetic fields, the conductivity exhibits a series of peaks, whose values depend only on the natural constants and the Landau level index. The conductivity of undoped systems is always given by a universal conductivity \(e^{2}/\pi^{2}\hbar\) independent of a magnetic field.
508 citations
TL;DR: In this paper, the effective potential of an impurity in a k · p scheme is derived in two-dimensional graphite sheet, and the crossover between these two regimes occurs around the range smaller than the lattice constant.
Abstract: The effective potential of an impurity in a k · p scheme is derived in two-dimensional graphite sheet. When the potential range is smaller than the lattice constant, it has an off-diagonal matrix element between K and K ′ points comparable to the diagonal element. With the increase of the range, this off-diagonal element decreases rapidly and the diagonal element for envelopes at A and B sites becomes identical. The crossover between these two regimes occurs around the range smaller than the lattice constant. In the latter regime, back scattering between states with + k and - k vanishes identically for the bands crossing the Fermi level in the absence of a magnetic field, leading to an extremely large conductivity. The absence of the back scattering disappears in magnetic fields, giving rise to a huge positive magnetoresistance.
415 citations
TL;DR: Experimental, phenomenological, and theoretical analyses are given of the dependence on strain of the ferromagnetic Tc of the colossal magnetoresistance (CMR) rare earth manganese perovskites as discussed by the authors.
Abstract: Experimental, phenomenological, and theoretical analyses are given of the dependence on strain of the ferromagnetic Tc of the colossal magnetoresistance (CMR) rare earth manganese perovskites. It is found that Tc is extremely sensitive to biaxial strain; by implication other physical properties are also. The results indicate that biaxial strain is an important variable which must be considered in the design of devices based on thin films and provide evidence in favor of the relevance of the Jahn–Teller electron-phonon coupling to the CMR phenomenon.
369 citations
TL;DR: In this paper, the temperature dependence of spin-polarized tunneling is investigated between 77 and 420 K for various ferromagnetic tunnel junctions, and the dominant one is elastic, spinpolarised tunneling between the two spin electrodes, each with an electron polarization $P$ that decreases with increasing temperature.
Abstract: The temperature dependence of spin-polarized tunneling is investigated between 77 and 420 K for various ferromagnetic tunnel junctions. Both the junction resistance and the magnetoresistance decrease with increasing temperature $T.$ The experimental results are successfully described by a model that includes two current contributions. The dominant one is elastic, spin-polarized tunneling between the two ferromagnetic electrodes, each with an electron polarization $P$ that decreases with $T$ due to thermally excited spin waves according to $P\ensuremath{\propto}(1\ensuremath{-}\ensuremath{\alpha}{T}^{3/2}),$ i.e., in the same way as the surface magnetization. A smaller second conductance is due to assisted, spin-independent tunneling which we find to be proportional to ${T}^{1.35\ifmmode\pm\else\textpm\fi{}0.15}.$
360 citations
TL;DR: In this article, a surface and/or interface related dead-layer is inferred from the thickness dependent resistance and magnetoresistance of uniform, ultra-thin films of La 0.67, Sr 0.33 and NdGaO_3.
Abstract: To understand the near-interface magnetism in manganites, uniform, ultra-thin films of La_{0.67}Sr_{0.33}MnO_3 were grown epitaxially on single crystal (001) LaAlO_3 and (110) NdGaO_3 substrates. The temperature and magnetic field dependent film resistance is used to probe the film's structural and magnetic properties. A surface and/or interface related dead-layer is inferred from the thickness dependent resistance and magnetoresistance. The total thickness of the dead layer is estimated to be $\sim 30 \AA$ for films on NdGaO_3 and $\sim 50 \AA$ for films on LaAlO_3.
358 citations
TL;DR: In this article, the magnetoresistance behavior of Fe3O4 in polycrystalline thin film, powder compact, and single-crystal form is compared and it is shown that negative magnetoreduction with peaks at the coercive field, observed in thin films and powder compacts but not in the single crystal, is due to fieldinduced alignment of the magnetization of contiguous grains.
Abstract: The magnetoresistance behavior of Fe3O4 in polycrystalline thin film, powder compact, and single-crystal form are compared. Negative magnetoresistance with peaks at the coercive field, observed in thin films and powder compacts but not in the single crystal, is due to field-induced alignment of the magnetization of contiguous grains. The effect is associated with intergranular transport of spin-polarized electrons.
355 citations
Journal Article•
TL;DR: In this paper, the first-principles band calculation predicts that the half metallic ground state with the ferrimagnetic coupling of Fe and Re spins is obtained for polycrystalline ceramics with Curie temperature above 400 K. The experimental results of electronic and magnetic properties are in accord with this picture.
Abstract: Intergrain tunneling magnetoresistance (TMR) subsisting up to room temperature has been observed for polycrystalline ceramics of ${\\mathrm{Sr}}_{2}{\\mathrm{FeReO}}_{6},$ which has ordered double perovskite structure with Curie temperature above 400 K. The first-principles band calculation predicts that ${\\mathrm{Sr}}_{2}{\\mathrm{FeReO}}_{6}$ shows the half metallic ground state with the ferrimagnetic coupling of Fe and Re spins. The experimental results of electronic and magnetic properties are in accord with this picture. In fact, the magnitude of intergrain TMR with the magnetic field of 7 T at 4.2 and 300 K is as large as 21 and 7%, respectively, reflecting high spin polarization of carriers.
341 citations
TL;DR: In this article, the half-metallic ferromagnetic powders of the halfmetallic granular metal are dielectric granular metals and the negative magnetoresistance is due to tunneling between contiguous magnetagnetic particles along a critical path with a spin-dependent Coulomb gap.
Abstract: Cold-pressed powders of the half-metallic ferromagnet ${\mathrm{CrO}}_{2}$ are dielectric granular metals. Hysteretic magnetoresistance with maxima at the coercive field arises from interparticle contacts. Dilution with insulating antiferromagnetic ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ powder reduces the conductivity by 3 orders of magnitude, but enhances the magnetoresistance ratio which reaches 50% at 5K. The negative magnetoresistance is due to tunneling between contiguous ferromagnetic particles along a critical path with a spin-dependent Coulomb gap.
TL;DR: In this paper, the authors investigated the magnetic-field-induced phase transitions of the charge carriers and found that the destruction of the real-space ordering is accompanied with a structural phase transition as well as with the magnetic phase transition and the colossal magnetoresistance effect.
Abstract: We have investigated the magnetic-field-induced phase transitions of ${R}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ($R=\mathrm{Pr}$ and Nd, $x=0.50,$ 0.45 and 0.50, 0.45, 0.40) by measurements of magnetization, magnetoresistance, and magnetostriction utilizing a nondestructive long-pulse magnet (generating up to 40 T). We observed processes where magnetic fields destroy the real-space ordering of the charge carriers and cause insulator-to-metal phase transitions over the whole temperature region below about 250 K. We found that the destruction of the charge ordering is accompanied with a structural phase transition as well as with the magnetic phase transition and the colossal magnetoresistance effect. The different profiles of the temperature vs transition field curve depending on the carrier concentration $x$ may be ascribed to the difference in the entropy between the commensurate and the discommensurate charge-ordered state. It turned out that the stability of the charge-ordered state is strongly correlated with the colinear antiferromagnetic ordering of the localized Mn moments.
TL;DR: In this paper, the Coulomb blockade regime was used to analyze electron tunneling in a double junction consisting of two ferromagnetic electrodes, with a small metal grain in between, and the corresponding oscillation period depends on the charging energy.
Abstract: Electron tunneling in a double junction consisting of two ferromagnetic electrodes, with a small ferromagnetic metallic grain in between, is analyzed theoretically in the Coulomb blockade regime. A new phenomenon, that of oscillations in tunneling magnetoresistance due to discrete charging effects, is predicted. The corresponding oscillation period depends on the charging energy, and the oscillations disappear when both junctions have the same spin asymmetry. The interplay of the oscillations and a nonoscillatory voltage dependence of the magnetoresistance is also analyzed.
TL;DR: In this paper, the authors discuss the different factors which govern the magnetic and transport properties of manganites with perovskite structure: carrier concentration, average size of the interpolated cation, and mismatch effect on the A-site.
Abstract: Manganites with the perovskite structure represent a very important family of oxides which are extensively studied for their colossal magnetoresistance (CMR) properties In the present review we discuss the different factors which govern the magnetic and transport properties of these materials: carrier concentration, average size of the interpolated cation, and mismatch effect on the A-site Three types of oxides are mainly examined: (i) the hole doped manganites Ln07A03MnO3 (A = Ca, Sr, Ba), (ii) the “charge ordered” Ln05A05MnO3 manganites, and (iii) the electron doped manganites Ca1-xLnxMnO3 and Ca1-xThxMnO3 The relationships between structural and magnetic transitions are discussed, and particular attention is paid to charge ordering phenomena The doping of the Mn sites by various elements (Al, Ga, In, Ti, Sn, Fe, Cr, Co, Ni) is systematically examined The beneficial effect of “Cr, Co, Ni” elements, which induce CMR properties in these perovskites, is emphasized
TL;DR: In this paper, the effect of domain walls on electron transport has been investigated in microfabricated Fe wires (0.65 to 20 mm linewidths) with controlled stripe domains.
Abstract: The effect of domain walls on electron transport has been investigated in microfabricated Fe wires (0.65 to 20 mm linewidths) with controlled stripe domains. Magnetoresistance (MR) measurements as a function of domain wall density, temperature, and the angle of the applied field are used to determine the low field MR contributions due to conventional sources in ferromagnetic materials and that due to the erasure of domain walls. A negative domain wall contribution to the resistivity is found. This result is discussed in light of a recent theoretical study of the effect of domain walls on quantum transport. [S0031-9007(98)06392-3]
TL;DR: In this paper, the conductivity and magnetoresistance of poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDT/PSS) have been studied as a function of temperature.
TL;DR: In this article, an array of semimetallic Bi nanowires have been successfully fabricated by electrodeposition, each nanowire consists of elongated Bi grains along the wire direction.
Abstract: Arrays of semimetallic Bi nanowires have been successfully fabricated by electrodeposition. Each nanowire consists of elongated Bi grains along the wire direction. Very large positive magnetoresistance of 300% at low temperatures and 70% at room temperature with quasilinear field dependence has been observed. These features are desirable for wide-range field sensing applications.
TL;DR: In this paper, the top and bottom Fe3O4 layers were grown on MgO substrates with a CoCr2O4 buffer layer to achieve different coercivities.
Abstract: Micron-size magnetic tunnel junctions consisting of ferromagnetic Fe3O4 electrodes, with MgO as a barrier layer, have been fabricated on (100) MgO substrates. Reflection high-energy electron diffraction and transmission electron microscopy studies reveal that the Fe3O4/MgO/Fe3O4 trilayers grown by pulsed laser deposition are heteroepitaxial with abrupt interfaces. To achieve different coercivities for the top and bottom Fe3O4 layers, the trilayers are grown on MgO substrates with a CoCr2O4 buffer layer. The junctions exhibit nonlinear current–voltage characteristics and changes in junction resistance with applied field corresponding to the coercivities of the two magnetic layers. However, the observed magnetoresistance (∼0.5% at 300 K, ∼1.5% at 150 K) is much lower than would be expected for a highly spin-polarized system. Possible reasons for the reduced magnetoresistance are discussed.
TL;DR: In this paper, the tunneling magnetoresistance (TMR) values were obtained by vacuum anneal (at temperatures from 100 to 240 °C for over 5 h) of junctions prepared with as-deposited TMR of 21%±1.7%, and an as deposited resistance area product of 25±6 kΩ×μm2.
Abstract: Spin tunnel junctions with tunneling magnetoresistance of 36.5%±0.5%, resistance-area product of 35±6 kΩ×μm2, and junction area between 6 and 75 μm2 were fabricated. The barrier height is 2.5±0.3 eV and the barrier thickness is 7.7±0.3 A. Large tunneling magnetoresistance (TMR) values are obtained by vacuum anneal (at temperatures from 100 to 240 °C for over 5 h) of junctions prepared with as-deposited TMR of 21%±1.7%, and an as-deposited resistance-area product of 25±6 kΩ×μm2. Two regimes occur during anneal. The first one occurs for anneals up to 200 °C where TMR and junction resistance increase, but the barrier parameters are unaltered. The second occurs above 200 °C, where TMR increases faster, together with an increase in barrier height. At 240 °C, TMR starts to decrease. Rutherford backscattering analysis indicates an asymmetry in the oxygen distribution in the as-deposited barrier. The oxygen distribution becomes homogeneous for anneals above 150 °C.
TL;DR: In this paper, the voltage dependence of magnetoresistance in spin dependent tunneling (SDT) junctions was studied experimentally and theoretically, and a phenomenological model based on a spin-independent two-step tunneling via defect states in the barrier, in addition to the spin-dependent direct tunneling, was proposed to account for the MR-V dependence.
Abstract: The voltage dependence of magnetoresistance in spin dependent tunneling (SDT) junctions was studied experimentally and theoretically. Different magnetoresistance (MR)-V dependence in various patterned junctions was observed and correlated with other technologically important parameters, including the magnitude of the MR, linearity of the current–voltage characteristic, temperature dependence of the junction resistance, and the MR. A phenomenological model based on a spin-independent two-step tunneling via defect states in the barrier, in addition to the spin-dependent direct tunneling, is proposed to account for the MR-V dependence. The MR ratio is determined by the ratio of the two currents. The MR-V dependence results from a stronger voltage dependence of the two-step tunneling current compared to that of the direct tunneling current. The same model also satisfactorily predicts other properties of SDT junctions. A high quality barrier is required to minimize the MR-V dependence and improve other junction properties. The approach to achieving desirable junction impedance for data storage applications is discussed.
TL;DR: In this paper, a first-order magnetostructural transition at TC≅240 K, from a high temperature paramagnetic to a low-temperature ferromagnetic phase, accompanied by a large drop in the resistivity was observed.
Abstract: Zero-field electrical resistivity over the temperature range of 4–300 K and magnetoresistance in magnetic fields of up to 12 T have been measured in Gd5(Si1.8Ge2.2). This system undergoes a first-order magnetostructural transition at TC≅240 K, from a high-temperature paramagnetic to a low-temperature ferromagnetic phase, accompanied by a large drop in the resistivity. The application of an external magnetic field above TC can induce this transition, and a giant negative magnetoresistance effect (Δρ/ρ≅−20%) is observed associated with this first-order field-induced transition.
TL;DR: In this paper, a pinned spin-dependent tunneling device was fabricated and tested in a mode suited for low-field sensing, achieving a sensitivity of 3%/Oe with negligible hysteresis.
Abstract: Pinned spin-dependent tunneling devices were fabricated and tested in a mode suited for low-field sensing. The basic structure of the devices was NiFeCo125/Al2O325/CoFe70/Ru9/CoFe70/ FeMn125 (in A). This structure had a tunneling resistivity of 110 MΩ μm2 and exhibited a 20% magnetoresistance when a field was swept along the easy direction of the soft electrode. High sensitivity, low hysteresis operation was achieved by applying a bias field orthogonal to the easy axis. A sensitivity of 3%/Oe with negligible hysteresis was observed using this mode of operation. A sensor using this type of material was designed to achieve a minimum resolvable field in the picotesla range. The sensor consists of a bridge with four elements, each having 16 tunnel junctions in series. A signal-to-noise ratio of 1:1 at 1 pT (10−8 Oe) is possible assuming achievable values for the tunneling resistivity, device size, bias level, and sensitivity.
TL;DR: In this article, the effects of interactions (dipolar and exchange) on the magnetic behavior of granular solid systems are examined using a Monte Carlo model capable of predicting the temperature and time dependence of the magnetic properties.
Abstract: The effects of interactions (dipolar and exchange) on the magnetic behavior of granular solid systems are examined using a Monte Carlo model capable of predicting the temperature and time dependence of the magnetic properties. Using this model the interaction effects on the magnetization and the magnetoresistance are studied. The results show that these properties depend critically on the strength and nature of the interactions. Magnetostatic interactions are found to decrease both remanence and coercivity and Hc is predicted to decrease linearly with concentration. It is shown that spatial disorder may be responsible for an increase of coercivity with exchange coupling which has been observed in some experimental studies. In systems with no hysteresis, magnetostatic interaction effects are found to increase the superparamagnetic transition temperature, in agreement with experimental data and previous analytical treatments. Calculations of the giant magnetoresistance (GMR) show that magnetostatic interact...
TL;DR: In this article, the spin spin of an electron tunneling in a junction made up of magnetic electrodes is studied and it is found that magnetic impurities give a contribution which increases the resistance and lowers the magnetoresistance, which saturates at low temperatures.
Abstract: Processes which flip the spin of an electron tunneling in a junction made up of magnetic electrodes are studied. It is found that (i) magnetic impurities give a contribution which increases the resistance and lowers the magnetoresistance, which saturates at low temperatures. The conductance increases at high fields. (ii) Magnon assisted tunneling reduces the magnetoresistance as ${T}^{3/2}$ and leads to a nonohmic contribution to the resistance which goes as ${V}^{3/2}.$ (iii) Surface antiferromagnetic magnons, which may appear if the interface has different magnetic properties from the bulk, gives rise to ${T}^{2}$ and ${V}^{2}$ contributions to the magnetoresistance and resistance, respectively. (iv) Coulomb blockade effects may enhance the magnetoresistance, when transport is dominated by cotunneling processes.
TL;DR: A Boltzmann equation analysis of the transport properties of a model of electrons with a lifetime that is short everywhere except near the Brillouin-zone diagonals is presented in this paper.
Abstract: We present a Boltzmann equation analysis of the transport properties of a model of electrons with a lifetime that is short everywhere except near the Brillouin-zone diagonals. The assumed lifetime is directly implied by photoemission and $c$-axis transport data. We find quantitative agreement between calculations and ac and dc longitudinal and Hall resistivity, but the predicted longitudinal magnetoresistance disagrees with experiment. A possible microscopic origin of the anomalous lifetime is discussed.
TL;DR: In this paper, the magnetotransport properties of ultrafine single-crystalline Bi nanowire arrays embedded in a dielectric matrix were measured at low temperatures and the wire boundary scattering was shown to be the dominant scattering process for carriers.
Abstract: We have measured the magnetotransport properties of ultrafine single-crystalline Bi nanowire arrays embedded in a dielectric matrix. At low temperatures (T⩽50 K), the wire boundary scattering is shown to be the dominant scattering process for carriers. A reversal in the temperature dependence of the magnetoresistance was observed for wires with 65 nm average diameter relative to those with 109 nm average diameter when T⩽100 K. We attribute this difference to effects due to the quantization of the transverse momentum of the carriers, which results in a semimetal-semiconductor transition for Bi nanowires as the wire diameter becomes sufficiently small.
TL;DR: In this paper, the electron concentration of perovskites has been investigated and the effect of electron concentration on magnetoresistance has been shown to be the predominant one by comparing the effects of Ln3+ and Th4+ on the magnetoreduction.
Abstract: Magnetotransport properties of the Mn(IV)-rich perovskites Ca1-xLnxMnO3 and Ca1-xThxMnO3 (0 ≤ x ≤ 0.20) have been systematically investigated. Among the different factors governing their colossal magnetoresistance (CMR), we demonstrate that the electron concentration is the predominant one by comparing the effects of Ln3+ and Th4+, the optimal x value giving the highest magnetoresistance being twice for the former compared to the latter, in accordance with their respective oxidation states. CMR is linked to the ferromagnetism−antiferromagnetism competition that is maximum for xopt = 0.08 in the case of Th, whereas xopt increases from x = 0.135 for Pr to x = 0.16 for Ho.
Patent•
IBM1
TL;DR: In this paper, a magnetic tunnel junction (MTJ) magnetoresistive (MR) read head has one fixed and one sensing ferromagnetic layer on opposite sides of the tunnel barrier layer.
Abstract: A magnetic tunnel junction (MTJ) magnetoresistive (MR) read head has one fixed ferromagnetic layer and one sensing ferromagnetic layer on opposite sides of the tunnel barrier layer, and with a biasing ferromagnetic layer in the MTJ stack of layers that is magnetostatically coupled with the sensing ferromagnetic layer to provide either longitudinal bias or transverse bias or a combination of longitudinal and transverse bias fields to the sensing ferromagnetic layer. The magnetic tunnel junction in the MTJ MR head is formed on an electrical lead on a substrate and is made up of a stack of layers. The layers in the stack are an antiferromagnetic layer, a fixed ferromagnetic layer exchange biased with the antiferromagnetic layer so that its magnetic moment cannot rotate in the presence of an applied magnetic field, an insulating tunnel barrier layer in contact with the fixed ferromagnetic layer, a sensing ferromagnetic layer in contact with the tunnel barrier layer and whose magnetic moment is free to rotate in the presence of an applied magnetic field, a biasing ferromagnetic layer that has its magnetic moment aligned generally within the plane of the device and a nonmagnetic electrically conductive spacer layer separating the biasing ferromagnetic layer from the other layers in the stack. The self field or demagnetizing field from the biasing ferromagnetic layer magnetostatically couples with the edges of the sensing ferromagnetic layer to stabilize its magnetic moment, and, to linearize the output of the device. The electrically conductive spacer layer prevents direct ferromagnetic coupling between the biasing ferromagnetic layer and the other layers in the stack and allows sense current to flow perpendicularly through the layers in the MTJ stack.