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

By J. Bass, W. Pratt. 2006

557 citations recorded by the source corpus.

In magnetoresistance (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. Spin-flipping within metals is described by a spin-diffusion length, lsfM, 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, lsfN 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 lsfF 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, δM1/M2, which determines the spin-flipping probability, P = 1−exp(−δ). Increasing δM1/M2 usually decreases the MR. We list measured values of these parameters and discuss the limitations on their determinations.

Subfields: Atomic and Molecular Physics, and Optics, Condensed Matter Physics

View Paper: https://www.semanticscholar.org/paper/15e7507211866758e05223250477227e8d38a19a

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In Atomic and Molecular Physics, and Optics

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Citations in the corpus

Shaped angular dependence of the spin-transfer torque and microwave generation without magnetic field (2007, methodology): “With respect to standard structures like Co/Cu/Co or Py/Cu/Py, the difference we have introduced is a large asymmetry between the spin diffusion lengths (SDL) in the magnetic layers, with a long SDL in Co ≈ 38 nm (at room temperature) and a short SDL in Py ≈ 4 nm [22-23].”
Transmission of electrical signals by spin-wave interconversion in a magnetic insulator (2010, background): “Extensive studies of conduction-electron spin currents in metals and semiconductors have clarified that the currents have a critical problem; they disappear within a very short distance, typically hundreds of nanometres 16 .”
Antiferromagnetic spintronics (2016, background): “This proportionality suggests that spin relaxation in these XMn alloys is mostly due to diffusion mechanisms (Bass and Pratt, 2007).”
Interface-Induced Phenomena in Magnetism (2016, unknown): “Al, for example, reported values vary from >100 μm in annealed bulk samples [Johnson and Silsbee, 1985; Bass and Pratt, 2007], to ≈100 nm to 1000 nm in polycrystalline films [Bass and Pratt, 2007; O’Brien et al., 2014].”