Electronic devices that use the spin degree of freedom hold unique prospects for future technology. The performance of these 'spintronic' devices relies heavily on the efficient transfer of spin polarization across different layers and interfaces. This complex transfer process depends on individual material properties and also, most importantly, on the structural and electronic properties of the interfaces between the different materials and defects that are common to real devices. Knowledge of these factors is especially important for the relatively new field of organic spintronics, where there is a severe lack of suitable experimental techniques that can yield depth-resolved information about the spin polarization of charge carriers within buried layers of real devices. Here, we present a new depth-resolved technique for measuring the spin polarization of current-injected electrons in an organic spin valve and find the temperature dependence of the measured spin diffusion length is correlated with the device magnetoresistance.R ecently great efforts have been undertaken to use the spin degree of freedom in electronic devices. These activities are fuelled by the potential prospects of spin-electronic (or 'spintronic') devices for example in terms of increased processing speed and integration, non-volatility, reduced power consumption, multifunctionality and their suitability for quantum computing 1 . The most common method for using the spin in devices is based on the alignment of the electron spin ('up' or 'down') relative to either a reference magnetic field or the magnetization orientation of a ferromagnetic layer. Device operation normally proceeds with measuring a quantity such as the electrical current that depends on how the degree of spin alignment is transferred across the device. The so-called 'spin valve' is a prominent example of such a spin-enabled device that has already revolutionized hard-drive read heads and magnetic memory 1 . The efficient transfer of spin polarization in real device structures remains one of the most difficult challenges in spintronics, because it is dependent on more than just the properties of the individual materials that comprise the device.Recently 2,3 , the use of organic materials in spintronics has become of significant interest, primarily owing to their ease and small cost of processing and electronic and structural flexibility. Furthermore, the extremely long spin coherence times found in organic materials offer considerable advantages over other materials 3 . This favourable property is related to two factors, first the weak spin-orbit coupling of light elements such as carbon and second to the small nuclear hyperfine interaction 4,5 . The latter arises because the electron transport in π-conjugated molecules is normally confined to molecular states, delocalized to the carbon rings, the predominant isotope of which, 12 C, has zero nuclear spin 4 .A common way to measure spin diffusion is based on time-resolved optical techniques, where spin-polarized charge carrie...

Artificial multilayers offer unique opportunities for combining materials with antagonistic orders such as superconductivity and ferromagnetism and thus to realize novel quantum states. In particular, oxide multilayers enable the utilization of the high superconducting transition temperature of the cuprates and the versatile magnetic properties of the colossal-magnetoresistance manganites. However, apart from exploratory work, the in-depth investigation of their unusual properties has only just begun. Here we present neutron reflectometry measurements of a [Y(0.6)Pr(0.4)Ba(2)Cu(3)O(7) (10 nm)/La(2/3)Ca(1/3)MnO(3) (10 nm)](10) superlattice, which reveal a surprisingly large superconductivity-induced modulation of the vertical ferromagnetic magnetization profile. Most surprisingly, this modulation seems to involve the density rather than the orientation of the magnetization and is highly susceptible to the strain, which is transmitted from the SrTiO(3) substrate. We outline a possible explanation of this unusual superconductivity-induced phenomenon in terms of a phase separation between ferromagnetic and non-ferromagnetic nanodomains in the La(2/3)Ca(1/3)MnO(3) layers.