There has been recent controversy about the magnitude of spin-flipping in the heavy metal Pt, characterized by the spindiffusion length . We propose a resolution of this controversy, and also present evidence for the importance of a phenomenon neglected in prior studies of transport across sputtered Ferromagnet/Pt (F/Pt) interfaces, spin-flipping at the interface. The latter is characterized by an interface spin-flipping parameter, δ Co/Pt , that specifies the probability P = [1 -exp(δ)] of a conduction electron flipping its spin direction as it traverses a Co/Pt interface. From studies of the Current-Perpendicular-to-Plane (CPP) Resistances and Magnetoresistances of sputtered ferromagnetically coupled Co/Pt multilayers by themselves, and embedded within Py-based Double Exchange-biased Spin-Valves, we derive values at 4.2K of δ Co/Pt = 0.9 -. . , interface specific resistance, AR / * = 0.74 ± 0.15 fΩm 2 , and interface spin-scattering asymmetry, γ Co/Pt = 0.53 ± 0.12. This value of δ Co/Pt is much larger than ones previously found for five other interfaces involving Co but not Pt. To derive δ requires knowledge of for our sputtered Pt, which we obtain from separate measurements. Combining our results with those from others, we find that for Pt is approximately proportional to the inverse resistivity, 1/ρ Pt .

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We describe a technique, using the current-perpendicular-to-plane (CPP) geometry, to measure the parameter δ F/N , characterizing flipping of electron spins at a ferromagnetic/non-magnetic (F/N) metallic interface. The technique involves measuring the CPP magnetoresistance of a sample containing a ferromagnetically coupled [F/N] n multilayer embedded within the 20 nm thick central Cu layer of a symmetric Py-based, double exchange-biased spin-valve. To focus on δ F/N , the F-and N-layers are made thin compared to their spin-diffusion lengths. We test the technique using F/N = Co/Cu. Analysing with no adjustable parameters, gives inconsistency with δ Co/Cu = 0, but consistency with our prior value of δ Co/Cu = 0.25 ± 0.1. Taking δ Co/Cu as adjustable gives δ Co/Cu = 33 . 0

From measurements of the current-perpendicular-to-plane (CPP) total specific resistance (AR = area times resistance) of sputtered Pd/Ir multilayers, we derive the interface specific resistance, 2AR Pd/Ir = 1.02 ± 0.06 fΩm 2 , for this metal pair with closely similar lattice parameters. Assuming a single fcc crystal structure with the average lattice parameter, no-free-parameter calculations, including only spd orbitals, give for perfect interfaces, 2AR Pd/Ir (Perf) = 1.21 ± 0.1 fΩm 2 , and for interfaces composed of two monolayers of a random 50%-50% alloy, 2AR Pd/Ir (50/50) = 1.22 ± 0.1 fΩm 2 . Within mutual uncertainties, these values fall just outside the range of the experimental value. Updating to add f-orbitals gives 2AR Pd/Ir (Perf) = 1.10 ± 0.1 fΩm 2 and 2AR Pd/Ir (50-50) = 1.13 ± 0.1 fΩm 2 , values now compatible with the experimental one. We also update, with f-orbitals, calculations for other pairs.In electronic transport with current-flow perpen-dicular to the layer planes (CPP geometry) of a metallic multilayer, the interface specific resistance AR (area A through which the CPP-current flows times the sample resistance R) is a fundamental quantity. In the past few years, measurements of AR have been published for a range of metal pairs [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Special interest focuses upon pairs M1 and M2 that have the same crystal structure and closely the same lattice parameters a o -i.e., Δa/a o ≤ 1%, since AR for such pairs can be calculated with no free parameters. That is, taking a given crystal structure and a common a o as known, the electronic structures for M1 and M2 can be calculated without adjustment using the local density approximation, and then AR M1/M2 can be calculated without adjustment using a modified Landauer formula for either interfaces that are perfectly flat and not intermixed (perfect interfaces), or for interfaces composed of two or more monolayers (ML) of a 50%-50% random alloy (50-50 alloy) [16][17][18][19][20][21]. For all four such pairs (Ag/Au [18,20], Co/Cu [18,20,21], Fe/Cr [17,18], and Pd/Pt [12]) where experimental values of 2AR M1/M2 have been published, Table I shows that the previously calculated values for perfect and 2 ML thick alloyed interfaces of these pairs are not very different, and that the experimental values are generally consistent with both values to within mutual uncertainties.In contrast, when Δa/a o is ~ 10%, the agreement between experiment and theory is only semi-quantitativeexperiment and calculations differ by amounts as low as 50% to more than factors of two [11]. Moreover, a test [11] of decreasing the difference in lattice parameter from ~ 10% for Pd/Cu to ~ 5% for Pd/Ag and Pd/Au gave no improvement in agreement between experiment and theory. A subsequent comparison between calculations and experimental data on residual resistivities of a variety of impurities in different hosts showed that those calculations could be very sensitive to local strains [22]. Given these results, it seemed worthwhile to t...

Rice (Oryza sativa) plants expressing the XA21 cell-surface receptor kinase are resistant to Xanthomonas oryzae pv. oryzae (Xoo) infection. We previously demonstrated that expressing a chimeric protein containing the ELONGATION FACTOR Tu RECEPTOR (EFR) ectodomain and the XA21 endodomain (EFR:XA21) in rice does not confer robust resistance to Xoo. To test if the XA21 ectodomain is required for Xoo resistance, we produced transgenic rice lines expressing a chimeric protein consisting of the XA21 ectodomain and EFR endodomain (XA21:EFR) and inoculated these lines with Xoo. We also tested if the XA21:EFR rice plants respond to a synthetic sulfated 21 amino acid derivative (RaxX21-sY) of the activator of XA21-mediated immunity, RaxX. We found that five independently transformed XA21:EFR rice lines displayed resistance to Xoo as measured by lesion length analysis, and showed that five lines share characteristic markers of the XA21 defense response (generation of reactive oxygen species and defense response gene expression) after treatment with RaxX21-sY. Our results indicate that expression of the XA21:EFR chimeric receptor in rice confers resistance to Xoo. These results suggest that the endodomain of the EFR and XA21 immune receptors are interchangeable and the XA21 ectodomain is the key determinant conferring robust resistance to Xoo.