Impact of new magnetoresistive materials on magnetic recording heads (invited)

Brug, J. A.; Tran, Loc; Bhattacharyya, Manoj K.; Nickel, Janice H.; Anthony, Thomas; Jander, Albrecht

doi:10.1063/1.361763

Cited by 37 publications

(8 citation statements)

References 22 publications

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“…If a higher FMR frequency is used, the resonance will occur at higher field, but the line will be further broadened. In spin valves, 19 for which there is a great deal of technical interest, 22 FMR measurements of the antiferromagnet-pinned film are further complicated by the presence of a strong resonance from the free film that tends to swamp the signal from the pinned film.…”

Section: Measurements Near Perpendicular Resonancementioning

confidence: 99%

Ferromagnetic resonance studies of NiO-coupled thin films ofNi80Fe20

et al. 1998

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This paper describes ferromagnetic resonance ͑FMR͒ and magnetoresistive measurements of thin magnetic films coupled to antiferromagnetic films. First, FMR results for films of Ni 80 Fe 20 show that coupling to NiO produces the angular variation in the resonance field of the type expected for unidirectional exchange anisotropy. However, unidirectional anisotropy values measured by in-plane ferromagnetic resonance are roughly 20% less than the loop shift measured via magnetoresistance. The difference is attributed in part to asymmetry in the coercivity. Second, in addition to the unidirectional anisotropy, coupling to NiO produces an isotropic negative resonance field shift that is larger than the exchange anisotropy field. This isotropic field shift is not consistent with models of exchange anisotropy in which the ferromagnet spins couple to a static antiferromagnet spin structure. It is consistent with the existence of a rotatable anisotropy, explained in terms of the energetics of domain configurations in the NiO. Third, using unpinned films as references, unidirectional anisotropy is measured for the first time with the magnetization rotated out of the film plane, and is found to be in reasonable agreement with in-plane measurements.

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Section: Measurements Near Perpendicular Resonancementioning

confidence: 99%

Ferromagnetic resonance studies of NiO-coupled thin films ofNi80Fe20

et al. 1998

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“…The problem of spatially limiting Notch activation is partially solved through activity of fringe genes (9), which modulate the sensitivity of Notch for its ligands and contribute to spatially limiting Notch activity (8,10). Certain features of the abnormal wings in flies mutant for the nubbin gene suggested a possible role for Nubbin protein in spatially limiting Notch activity at the DV boundary of the wing (11,12). The nubbin gene encodes a POU domain protein that is expressed in the developing wing primordium (11) (Fig.…”

Section: Fig 3 (A) Common Base Characteristics Of Thementioning

confidence: 99%

“…1A). The row of sensory bristles that makes up the wing margin is disorganized in nubbin mutant wings (11), suggesting a defect in Wingless or Notch activity. In preparations where the wing margin is viewed edge on, this disorganization reflects a broadening of the region where bristles form (Fig.…”

Section: Fig 3 (A) Common Base Characteristics Of Thementioning

confidence: 99%

Room Temperature-Operating Spin-Valve Transistors Formed by Vacuum Bonding

Monsma

Vlutters

Lodder

1998

Science

209

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Functional integration between semiconductors and ferromagnets was demonstrated with the spin-valve transistor. A ferromagnetic multilayer was sandwiched between two device-quality silicon substrates by means of vacuum bonding. The emitter Schottky barrier injected hot electrons into the spin-valve base. The collector Schottky barrier accepts only ballistic electrons, which makes the collector current very sensitive to magnetic fields. Room temperature operation was accomplished by preparing Si-Pt-Co-Cu-Co-Si devices. The vacuum bonding technique allows the realization of many ideas for vertical transport devices and forms a permanent link that is useful in demanding adhesion applications.Ten years after its discovery (1), giant magnetoresistance (GMR) or, designated more appropriately, the spin-valve effect, has already shown its strength in applications such as read heads and magnetic random access memories (MRAMs). Driven by such lowfield applications, a search for higher sensitivities is continuing. In the spin-valve effect, majority carrier electrons with long mean free paths can travel with low resistance through a multilayer when a magnetic field aligns magnetizations of adjacent magnetic layers. In ordinary four-point resistance measurements with the current in plane (CIP), channeling, shunting, and diffusive surface scattering diminish and complicate the effect. Experiments with currents perpendicular to the planes (CPP) are very useful for fundamental studies of the electron transport process (2), yet application of the larger effect to sensors is cumbersome because of the very low resistances involved. We introduced the solidstate spin-valve transistor (SVT) structure as a spectroscopic tool to investigate transport properties of the CPP spin-valve effect and found a large, perpendicular, hot-electron spin-valve effect (3). In addition, we proposed to employ nonmagnetic and ferromagnetic tunnel barriers, of which experimental results were reported later (4). Such experiments had to be conducted at 77 K to decrease the collector leakage current with respect to the hot-electron current. Room-temperature (RT) operation requires a large emitter current density, reduction of the collector barrier area, increase of the collector barrier height, and enhancement of the base transport factor. In order to obtain sufficiently large injection current densities, a device-quality semiconductor layer would need to be grown on top of the metallic base. In practice, such layers grow poorly, so we instead turned to bonding the base between two crystalline substrates in air. This provided spontaneous adhesion based on van der Waals forces and hydrogen bonds between adsorbed water molecules. This bond was not strong enough, however, to allow lithographic processing. Our development of vacuum metal bonding during sputtering provided a superior bond and hot-electron transport in a nonmagnetic Si-Au-Ge metal base transistor (5). We have used this technique to prepare SVTs operating at RT. Because the RT operation now also p...

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“…The interest in such systems is related to the capability of controlling both the electrical conductivity and the magnetic character appropriately coupling different materials. Indeed multilayers have found application in magnetic recording systems and, more recently, in spintronic devices [4][5][6][7]. From a fundamental point of view the relationship between magnetism and structure is still an open question, which stimulated much theoretical research in the last decade [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Diode-pumped solid-state Nd³⁺:Ca₃Ga₂Ge₃O₁₂crystal lasers

et al. 2007

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The electronic structure and magnetic properties of 1 ML of iron on Cu(001) have been calculated using the embedding method within the density functional theory framework. The surface features will be described as concerns binding energies, dispersion and spin dependence. The changes in surface electronic states and magnetization, induced at the interface by the overlayer growth, will be evidenced, also analysing the electronic properties of the constituent elements of the system, clean substrate and unsupported iron monolayer. The different energy ranges of the two spin components in the Fe film reflect upon very different degrees of hybridization of these states with the substrate ones. This suggests that the overlayer states can be a spin fixed channel for conductivity, with interesting applications in devices in which the current should depend on the carriers' spin.

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Impact of new magnetoresistive materials on magnetic recording heads (invited)

Cited by 37 publications

References 22 publications

Ferromagnetic resonance studies of NiO-coupled thin films ofNi80Fe20

Ferromagnetic resonance studies of NiO-coupled thin films ofNi80Fe20

Room Temperature-Operating Spin-Valve Transistors Formed by Vacuum Bonding

Diode-pumped solid-state Nd³⁺:Ca₃Ga₂Ge₃O₁₂crystal lasers

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Impact of new magnetoresistive materials on magnetic recording heads (invited)

Cited by 37 publications

References 22 publications

Ferromagnetic resonance studies of NiO-coupled thin films ofNi80Fe20

Ferromagnetic resonance studies of NiO-coupled thin films ofNi80Fe20

Room Temperature-Operating Spin-Valve Transistors Formed by Vacuum Bonding

Diode-pumped solid-state Nd3+:Ca3Ga2Ge3O12crystal lasers

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Diode-pumped solid-state Nd³⁺:Ca₃Ga₂Ge₃O₁₂crystal lasers