With the inauguration of the small-angle instrument D11 of the Institute Laue–Langevin (ILL) in September 1972 neutron scattering revolutionized methods of contrast variation. Very soon D11 was ...oversubscribed by proposals relying on isotopic substitution of hydrogen isotopes. At the same time in Oxford first experiments of polarised neutron diffraction from dynamic polarised protons in lanthanum magnesium nitrate crystals demonstrated the great utility of this approach. In the early eighties a new type of polarised target material led to a boom of contrast variation by nuclear polarisation. The new samples of frozen solutions of macromolecules lent themselves to small-angle scattering. Often in collaboration with research centres of High Energy Physics various groups in Europe and Japan started experiments of polarized neutron scattering from dynamic polarised protons. Techniques of NMR and EPR considerably enlarged the spectrum of nuclear contrast variation. This is shown with time-resolved polarised neutron scattering from dynamic polarized proton spins of a free radical and of tyrosyl doped catalase using D22 at the ILL.
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Spin injection across the ferrimagnetic insulator (YIG)/normal metal (Au) interface was studied by ferromagnetic resonance. The spin mixing conductance was determined by comparing the Gilbert damping ...in bare YIG films with those covered by a Au/Fe/Au structure. The Fe layer in Au/Fe/Au acted as a spin sink as displayed by an increased Gilbert damping parameter α compared to that in the bare YIG. In particular, for the 9.0 nm YIG/2.0 nm Au/4.3 nm Fe/6.1 nm Au structure, the YIG and Fe films were coupled by an interlayer exchange coupling, and the exchange coupled YIG exhibited an increased Gilbert damping compared to the bare YIG. This relationship between static and dynamic coupling provides direct evidence for spin pumping. The transfer of spin momentum across the YIG interface is surprisingly efficient with the spin mixing conductance g(↑↓) ≃ 1.2 × 10(14) cm(-2).
Heinrich et al show that paramagnetic molecules on a superconducting substrate exhibit excited spin states with a lifetime of 10 ns. They ascribe this increase in lifetime by orders of magnitude to ...the depletion of electronic states around the Fermi level in the superconductor. This prohibits pathways of energy relaxation into the substrate and allows the magnetic molecule to be electrically pumped into higher spin states, making superconducting substrates prime candidates for spin manipulation. We further show that the proximity of the scanning tunnelling microscope tip modifies the magnetic anisotropy.
Strong damping enhancement in nm-thick yttrium iron garnet (YIG) films due to Pt capping layers was observed. This damping is substantially larger than the expected damping due to conventional spin ...pumping, is accompanied by a shift in the ferromagnetic resonance field, and can be suppressed by the use of a Cu spacer in between the YIG and Pt films. The data indicate that such damping may originate from the ferromagnetic ordering in Pt atomic layers near the YIG/Pt interface and the dynamic exchange coupling between the ordered Pt spins and the spins in the YIG film.
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•New fully biobased thermoplastic polyurethanes were synthesized and characterized.•Copolymers are synthesized with three different biobased building blocks.•Substitution of BDO by ...ISO altered the thermal behavior, and crystallinity.•All polymers showed hard and soft segments segregation.•Polyurethanes with low ISO contents show high elongations and modulus.
Different innovative macromolecular architectures have been elaborated and characterized. The synthesis of a set fully biobased thermoplastic polyurethanes (TPUs) was contingent on different renewable or potentially renewable building blocks such as 1,4-butanediol (BDO), isosorbide (ISO), and 2-heptyl-3,4-bis(9-isocyanatononyl)-1-pentylcyclohexane, the latter obtained after the chemical modification of a dimer fatty acid. These TPUs were prepared in a one-step bulk process using different hard segment (HS) species with varying ratios of ISO/BDO contents. The final molar masses were found to decrease when BDO was progressively exchanged by ISO, presumably due to the high dissymmetry and lesser reactivity of the latter species (bearing exo and endo groups) with respect to the former. This substitution (BDO vs. ISO) altered the crystallinity, the thermal transitions and the stability of the resulting polymers. TPUs with low ISO content present good mechanical performances with high elongation and Young’s Modulus. The deformation is however fully plastic, despite the “hard–soft” phase segregation proven by small-angle X-ray scattering analysis. These novel biobased materials are very attractive since they present highly tailorable properties by selecting appropriate HS content and suitable chemical structure.
Low-temperature spin-polarized scanning tunneling microscopy is employed to study spin transport across single cobalt-phthalocyanine molecules adsorbed on well-characterized magnetic nanoleads. A ...spin-polarized electronic resonance is identified over the center of the molecule and exploited to spatially resolve stationary spin states. These states reflect two molecular spin orientations and, as established by density functional calculations, originate from a ferromagnetic molecule-lead exchange interaction.
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