Thin film magnetoresistors in memory, storage, and related applications

Thompson, David A.; Romankiw, L. T.; Mayadas, A. F.

doi:10.1109/tmag.1975.1058786

Cited by 183 publications

(63 citation statements)

References 41 publications

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“…At such a high field the magnetization is expected to be parallel to the applied field. We found that R xx shows a cos 2 θ dependence and R xy follows a sinθcosθ dependence which is consistent with the AMR theory for a single domain ferromagnetic film 1 .We can see that the presence of Antiphase Boundaries (APBs) still does not alter the single-domain state-like behaviour of the film. APBs are an intrinsic consequence of the nucleation and growth mechanism in the film 10 .…”

Section: Resultssupporting

confidence: 86%

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Planar Hall effect in magnetite (100) films

Jin

Ramos

Yinqing

et al. 2006

Journal of Applied Physics

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Abstract.Giant Planar Hall effect (GPHE) has been observed in epitaxial magnetite (100) films grown on MgO substrates. The effect is manifested as jumps in the transverse resistivity when the film is subjected to a swept, in-plane magnetic field. The jumps are two orders of magnitude higher than previously observed in metallic ferromagnets.Recently, the same effect has been reported for other materials, but unlike our results, they present GPHE at low temperature only. The magnitude of the GPHE observed at room temperature has potential applications such as magnetic sensors and nonvolatile memory elements.

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Section: Resultssupporting

confidence: 86%

“…In the ferromagnetic films, the resistivity depends on the angle between the magnetization M and the current density J. For a single domain film, the electric field is given by 1 :…”

Section: Introductionmentioning

confidence: 99%

Planar Hall effect in magnetite (100) films

Jin

Ramos

Yinqing

et al. 2006

Journal of Applied Physics

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“…This is analogous to anisotropic magneto-resistance (AMR) [4], an important technology in magnetic field sensing applications [5] and of a similarly relativistic magnetic origin, but in this different fundamental electrical circuit element.…”

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confidence: 99%

Anisotropic magnetocapacitance in ferromagnetic-plate capacitors

et al. 2015

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The capacitance of a parallel plate capacitor can depend on applied magnetic field. Previous studies have identified capacitance changes induced via classical Lorentz force or spin-dependent Zeeman effects. Here we measure a magnetization direction dependent capacitance in parallel-plate capacitors where one plate is a ferromagnetic semiconductor, gallium manganese arsenide. This anisotropic magneto-capacitance is due to the anisotropy in the density of states dependent on the magnetization through the strong spin-orbit interaction.Capacitance, the ability of a body to retain charge is defined by the relation 1/C g = dV e /dq, the ratio of the change in electrostatic potential to the amount of charge added. In a simple parallel plate capacitor one normally calculates this capacitance through the change in electrostatic potential by integrating the electric field E due to charges on the surface of two metallic plates over the separating distance d. However, corrections to this electrostatic picture can be important, and other contributions to the change in potential when additional charge is added must be taken into account. It is often helpful to reformulate these corrections as effective series capacitances in series with a geometrical capacitance expected from the classical picture [1][2][3]. In particular, the effect of change in chemical potential due to the finite density of states can be important in low dimensional systems. This has been exploited for example in two-dimensional electron gases where the additional chemical contribution to the potential, the electron compressibility, allows probing of Landau levels in the density of states in the quantum Hall regime [2].In this Letter, we exploit this kind of capacitance correction to demonstrate an anisotropic magnetocapacitance (AMC). This is analogous to anisotropic magneto-resistance (AMR) [4], an important technology in magnetic field sensing applications [5] and of a similarly relativistic magnetic origin, but in this different fundamental electrical circuit element.In general, magnetic effects on transport properties such as AMR can be ascribed to three different categories: ordinary (orbital), due to the Lorentz force; spindependent, due to splitting of spin sub-bands through ferromagnetism or the Zeeman effect; and extraordinary, relativistic in origin through the spin-orbit interaction. Some well known examples of these effects in resistance are Lorentz magneto-resistance, giant magnetoresistance (GMR) [6], and AMR [7] respectively. Classifying magneto-capacitance along similar lines, both ordinary and spin-dependent effects have been observed previously. Changes in capacitance as a function of in-plane magnetic field have been measured in two-dimensional electron gases and attributed to combined Lorentz force and quantum confinement effects [8,9]; spin dependent effects have been considered theoretically [10], and experimentally measured due to the Zeeman splitting in Pd plate capacitors [11] and in magnetic tunnel junctions several measurements ...

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“…More recently, PHE has also been found in crystalline La 2=3 Fe 1=3 MnO 3 [8] and as a very large effect at low temperatures in the dilute magnetic semiconductor (Ga,Mn)As [9]. The transverse resistance xy characterizing the PHE and the longitudinal resistivity xx denoting the AMR are given by [10] xy ¼ ð k À ? Þ sinÈ cosÈ…”

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confidence: 99%

Origin of the Planar Hall Effect in NanocrystallineCo60Fe20B20

et al. 2011

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An angle dependent analysis of the planar Hall effect (PHE) in nanocrystalline single-domain Co 60 Fe 20 B 20 thin films is reported. In a combined experimental and theoretical study we show that the transverse resistivity of the PHE is entirely driven by anisotropic magnetoresistance (AMR). Our results for Co 60 Fe 20 B 20 obtained from first principles theory in conjunction with a Boltzmann transport model take into account the nanocrystallinity and the presence of 20 at. % boron. The ab initio AMR ratio of 0.12% agrees well with the experimental value of 0.22%. Furthermore, we experimentally demonstrate that the anomalous Hall effect contributes negligibly in the present case. DOI: 10.1103/PhysRevLett.107.086603 PACS numbers: 72.25.Ba, 71.70.Ej, 72.15.Gd Electron transport effects employing the electronic spin degree of freedom lie at the heart of spintronics and its applications not only in information technology [1] but more increasingly also in sensorics for biomedical purposes, where the utmost sensitivity for detecting minute magnetic stray fields is needed. The planar Hall effect (PHE) and the anomalous Hall effect (AHE) as well as tunneling magnetoresistance are promising phenomena for realizing highly sensitive sensors. From a materials point of view, nanocrystalline Co 60 Fe 20 B 20 (CoFeB) attracts growing attention since it combines large saturation magnetization with low coercivity [2,3], both favoring high sensitivities.PHE and AHE are both observed as a voltage transverse to the applied current [4,5] in contrast to the anisotropic magnetoresistance (AMR), which is measured in the longitudinal geometry. For PHE the magnetization M lies in the plane spanned by the current density j ¼ je x and the direction e y of the transverse voltage measurement, and for AHE the component of M perpendicular to j and e y matters. Although AMR has been known since Thomson's-later known as Lord Kelvin-observations in 1856 [6], PHE was discovered only a century later in polycrystalline permalloy [7]. More recently, PHE has also been found in crystalline La 2=3 Fe 1=3 MnO 3 [8] and as a very large effect at low temperatures in the dilute magnetic semiconductor (Ga,Mn)As [9]. The transverse resistance xy characterizing the PHE and the longitudinal resistivity xx denoting the AMR are given by [10] xy ¼ ð k À ? Þ sinÈ cosÈwhere k ( ? ) is the resistivity along (perpendicular to) the direction of the in-plane component of M, and È is the angle enclosed by j and M. A transverse voltage arises whenever the current is neither perpendicular nor parallel to the magnetization. Even though the AMR is a subtle spin-orbit effect, quantitatively reliable predictions from first principles based on the density functional theory (DFT) can be made [11,12]. In this Letter, we elucidate the role of AMR in the PHE in nanocrystalline Co 60 Fe 20 B 20 thin films experimentally and by ab initio calculations. We measure AMR and PHE in longitudinal and transverse four-probe transport experiments. The single-domain behavior enforced by an ...

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Thin film magnetoresistors in memory, storage, and related applications

Cited by 183 publications

References 41 publications

Planar Hall effect in magnetite (100) films

Planar Hall effect in magnetite (100) films

Anisotropic magnetocapacitance in ferromagnetic-plate capacitors

Origin of the Planar Hall Effect in NanocrystallineCo60Fe20B20

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