Perpendicular giant magnetoresistances of Ag/Co multilayers

Pratt, W. P.; Lee, S. F.; Slaughter, J. M.; Loloee, R.; Schroeder, P. A.; Bass, J.

doi:10.1103/physrevlett.66.3060

Cited by 635 publications

(264 citation statements)

References 21 publications

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“…The predicted absence of a GMR in the usual sense [g(θ) is equal for θ = 0 and π] requires some clarification, as GMR has been observed in multilayers with superconducting contacts [19], in contrast to our predictions and those of Ref. [11].…”

Section: Scattering Matrices S E(h)e(h) Il(r)contrasting

confidence: 54%

Current-induced switching of magnetic domains to a perpendicular configuration

Waintal

Brouwer

2001

Phys. Rev. B

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In a ferromagnet-normal-metal-ferromagnet trilayer, a current flowing perpendicularly to the layers creates a torque on the magnetic moments of the ferromagnets. When one of the contacts is superconducting, the torque not only favors parallel or antiparallel alignment of the magnetic moments, as is the case for two normal contacts, but can also favor a configuration where the two moments are perpendicular. In addition, whereas the conductance for parallel and antiparallel magnetic moments is the same, signalling the absence of giant magnetoresistance in the usual sense, the conductance is greater in the perpendicular configuration. Thus, a negative magnetoconductance is predicted, in contrast with the usual giant magnetoresistance.PACS numbers: 75.70.Pa., 75.30.ds, 74.80Fp A system made of stacks of alternating ferromagnetic and non-magnetic metal layers shows Giant MagnetoResistance (GMR) [1]: When two consecutive magnetic layers have their magnetic moments aligned, the conductance is much bigger than when they are anti-aligned. A simple way to think about this effect is in term of two separate (i.e., incoherent) currents for the majority and minority electrons (electrons with spin parallel or antiparallel to the magnetic moment, respectively), and to view the ferromagnetic layers as spin filters that have different conductances for majority and minority electrons [2]. In the configuration where the magnetic moments are aligned, the majority electrons are well transmitted by both magnetic layers while the minority electrons are (mostly) reflected. When the moments are anti-aligned, the majority spin direction of one layer is the minority spin direction of its neighbor so that all the electrons are reflected. The role of the magnetic field is to align the initially anti-aligned magnetic moments, thus giving rise to an increase of the conductance.When the magnetic moments of the layers make an angle θ different from 0 or π, the simple "two-current" picture does not hold anymore; instead a description in terms of a coherent superposition of spin up and spin down is needed. While the component of the spin flux in the direction of the magnetic moment m of a ferromagnetic layer is conserved when an electric current is passed through the layer (since the fluxes of majority and minority spins are conserved individually), the spin flux perpendicular to m does not have to be conserved, as it depends on the coherence between majority and minority electrons. As first pointed out by Slonczewski [3] and Berger [4], the consequence of such a change of the magnetic moment carried by the current is that the current exerts a torque on the moments of the ferromagnets. This so-called "spin-transfer" torque vanishes at the two angles θ = 0 and θ = π, where the two current model applies. Experimentally, one studies a ferromagnet-normalmetal-ferromagnet (FNF) trilayer where one of the magnetic moments is held fixed, e.g. by using a thick ferromagnetic layer [5][6][7][8], while the other one is free to rotate. The current directi...

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Section: Scattering Matrices S E(h)e(h) Il(r)contrasting

confidence: 54%

Current-induced switching of magnetic domains to a perpendicular configuration

Waintal

Brouwer

2001

Phys. Rev. B

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“…The thickness must remain small compared to the distance over which the electrons remember their spin which for magnetic materials is on the order of one to twenty nanometers. For this reason, the first CPP-GMR measurements were performed using superconducting leads [4]. The first major application of CPP-GMR will probably be extremely small magnetic field sensors (∼10 nm), so small that their lateral dimensions are comparable to the film thickness.…”

Section: Spintronic Phenomenamentioning

confidence: 99%

Tunneling magnetoresistance from a symmetry filtering effect

Butler

2008

Science and Technology of Advanced Materials

135

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“…1͑c͔͒ like the perpendicular spin valves, studied thoroughly by Pratt and Bass c.s. 15 and others. 16,17 These studies provided a large body of evidence for the two-channel ͑i.e., spin-up and spindown͒ series resistor model and a wealth of accurate transport parameters such as the interface resistances for various material combinations.…”

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confidence: 99%

Universal angular magnetoresistance and spin torque in ferromagnetic/normal metal hybrids

et al. 2003

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The electrical resistance of ferromagnetic/normal-metal (F/N) heterostructures depends on the nature of the junctions that may be tunnel barriers, point contacts, or intermetallic interfaces. For all junction types, the resistance of disordered F/N/F perpendicular spin valves as a function of the angle between magnetization vectors is shown to obey a simple universal law. The spin-current induced magnetization torque can be measured by the angular magnetoresistance of these spin valves. The results are generalized to arbitrary magnetoelectronic circuits.

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Perpendicular giant magnetoresistances of Ag/Co multilayers

Cited by 635 publications

References 21 publications

Current-induced switching of magnetic domains to a perpendicular configuration

Current-induced switching of magnetic domains to a perpendicular configuration

Tunneling magnetoresistance from a symmetry filtering effect

Universal angular magnetoresistance and spin torque in ferromagnetic/normal metal hybrids

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