Mean Free Path Effects on the Current Perpendicular to the Plane Magnetoresistance of Magnetic Multilayers

Bozec, D.; Howson, M. A.; Hickey, B. J.; Shatz, Smadar; Wiser, Nathan; Tsymbal, Evgeny Y.; Pettifor, D. G.

doi:10.1103/physrevlett.85.1314

Cited by 50 publications

(60 citation statements)

References 25 publications

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“…In this Appendix we outline the results obtained, considering tests of both 2CSR and VF. This distinction is important, because two coupled groups [114,[117][118][119] have argued that a number of observed deviations from the 2CSR should be attributed not to effects of finite l sf via the VF model, but rather to mfp-effects (although we shall see that the two groups apply different mfp-models). We consider several experiments sequentially.…”

Section: Appendix C Consideration Of Mean-free-path Effects In Cpp Tmentioning

confidence: 96%

Spin-diffusion lengths in metals and alloys, and spin-flipping at metal/metal interfaces: an experimentalist’s critical review

Bass¹,

Pratt²

2007

J. Phys.: Condens. Matter

551

585

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In magnetoresistive (MR) studies of magnetic multilayers composed of combinations of ferromagnetic (F) and non-magnetic (N) metals, the magnetic moment (or related 'spin') of each conduction electron plays a crucial role, supplementary to that of its charge. While initial analyses of MR in such multilayers assumed that the direction of the spin of each electron stayed fixed as the electron transited the multilayer, we now know that this is true only in a certain limit. Generally, the spins 'flip' in a distance characteristic of the metal, its purity, and the temperature. They can also flip at F/N or N1/N2 interfaces. In this review we describe how to measure the lengths over which electron moments flip in pure metals and alloys, and the probability of spin-flipping at metallic interfaces. Spinflipping within metals is described by a spin-diffusion length, l M sf , where the metal M = F or N. Spin-diffusion lengths are the characteristic lengths in the current-perpendicular-to-plane (CPP) and lateral non-local (LNL) geometries that we focus upon in this review. In certain simple cases, l N sf sets the distance over which the CPP-MR and LNL-MR decrease as the N-layer thickness (CPP-MR) or N-film length (LNL) increases, and l F sf does the same for increase of the CPP-MR with increasing F-layer thickness. Spin-flipping at M1/M2 interfaces can be described by a parameter, δ M1/M2 , which determines the spin-flipping probability, P = 1 -exp(-δ). Increasing δ M1/M2 usually decreases the MR. We list measured values of these parameters and discuss the limitations on their determinations. OrganizationThis review is organized as follows. Section I provides a brief history and overview, defines the lengths of interest, briefly explains the physics underlying the spin-diffusion lengths that are the focus of the review, and discusses caveats on theoretical analysis and limitations on the measurements of the parameters of interest: the transport mean-free-path, λ t ; the spin-diffusion length in non-magnetic (N) metals or alloys, l N sf ; the spin-diffusion length in ferromagnetic (F) metals or alloys, l F sf ; and the interfacial spin-flip parameter, δ, where the spin-flipping probability is P = 1 -exp(-δ). Section II describes the different ways in which these parameters have been measured, and gives more specifics of their limitations. Section III contains four tables. Table I should be unique to each sample at 4.2K, but should be intrinsic in sufficiently high purity samples at 293K. Table III lists values of l F sf in ferromagnetic metals and alloys, mostly at 4.2K. Table IV lists values of δ N1/N2 for several N1/N2 metal pairs at 4.2K. Each table is preceded by some comments about the results. Section IV contains a brief summary and our conclusions. I. History, Overview, Definitions, and Caveats and Limitations. IA. History and Overview.The discovery in 1988 of Giant Magnetoresistance (GMR) in ferromagnetic/non-magnetic (F/N) metallic multilayers [1] [2] stimulated the growth of a new subfield of transport stud...

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Section: Appendix C Consideration Of Mean-free-path Effects In Cpp Tmentioning

confidence: 96%

Spin-diffusion lengths in metals and alloys, and spin-flipping at metal/metal interfaces: an experimentalist’s critical review

Bass¹,

Pratt²

2007

J. Phys.: Condens. Matter

551

585

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“…1c) have been studied thoroughly by the Michigan State University collaboration [39] and others [37,38,118,235,236] in perpendicular (CPP) spin valves. These experiments provided a large body of evidence for the two-channel (i.e.…”

Section: Angular Magnetoresistancementioning

confidence: 99%

Non-collinear magnetoelectronics

2006

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The electron transport properties of hybrid ferromagnetic|normal metal structures such as multilayers and spin valves depend on the relative orientation of the magnetization direction of the ferromagnetic elements. Whereas the contrast in the resistance for parallel and antiparallel magnetizations, the so-called Giant Magnetoresistance, is relatively well understood for quite some time, a coherent picture for non-collinear magnetoelectronic circuits and devices has evolved only recently. We review here such a theory for electron charge and spin transport with general magnetization directions that is based on the semiclassical concept of a vector spin accumulation. In conjunction with first-principles calculations of scattering matrices many phenomena, e.g. the currentinduced spin-transfer torque, can be understood and predicted quantitatively for different material combinations.

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“…The theory of the giant magnetoresistance (GMR) is still developing [1,2] and a number [3] of recent papers have interesting predictions about the nature of the electronic states in multilayers. In particular, the band structure that gives rise to spin-dependent scattering is thought to be responsible [4] for the spin-dependent confinement of electrons to specific layers within the system.…”

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confidence: 99%

Experimental Evidence for Electron Channeling in Fe/Au (100) Superlattices

et al. 2001

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'Experimental evidence for electron channeling in Fe/Au (100) superlattices.', Physical review letters., 86 (25).pp. 5787-5790.Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

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Mean Free Path Effects on the Current Perpendicular to the Plane Magnetoresistance of Magnetic Multilayers

Cited by 50 publications

References 25 publications

Spin-diffusion lengths in metals and alloys, and spin-flipping at metal/metal interfaces: an experimentalist’s critical review

Spin-diffusion lengths in metals and alloys, and spin-flipping at metal/metal interfaces: an experimentalist’s critical review

Non-collinear magnetoelectronics

Experimental Evidence for Electron Channeling in Fe/Au (100) Superlattices

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