Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics.

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Spintronics: Fundamentals and applications

A spin valve is a layered structure of magnetic and non-magnetic (spacer) materials whose electrical resistance depends on the spin state of electrons passing through the device and so can be controlled by an external magnetic field. The discoveries of giant magnetoresistance and tunnelling magnetoresistance in metallic spin valves have revolutionized applications such as magnetic recording and memory, and launched the new field of spin electronics--'spintronics'. Intense research efforts are now devoted to extending these spin-dependent effects to semiconductor materials. But while there have been noteworthy advances in spin injection and detection using inorganic semiconductors, spin-valve devices with semiconducting spacers have not yet been demonstrated. pi-conjugated organic semiconductors may offer a promising alternative approach to semiconductor spintronics, by virtue of their relatively strong electron-phonon coupling and large spin coherence. Here we report the injection, transport and detection of spin-polarized carriers using an organic semiconductor as the spacer layer in a spin-valve structure, yielding low-temperature giant magnetoresistance effects as large as 40 per cent.

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Giant magnetoresistance in organic spin-valves

The ability to manipulate electron spin in organic molecular materials offers a new and extremely tantalizing route towards spin electronics, both from fundamental and technological points of view. This is mainly due to the unquestionable advantage of weak spin–orbit and hyperfine interactions in organic molecules, which leads to the possibility of preserving spin-coherence over times and distances much longer than in conventional metals or semiconductors. Here we demonstrate theoretically that organic spin valves, obtained by sandwiching an organic molecule between magnetic contacts, can show a large bias-dependent magnetoresistance and that this can be engineered by an appropriate choice of molecules and anchoring groups. Our results, obtained through a combination of state-of-the-art non-equilibrium transport methods and density functional theory, show that although the magnitude of the effect varies with the details of the molecule, large magnetoresistance can be found both in the tunnelling and the metallic limit.

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Towards molecular spintronics.

High power pulsed magnetron sputtering (HPPMS) is an emerging technology that has gained substantial interest among academics and industrials alike. HPPMS, also known as HIPIMS (high power impulse ...

High power pulsed magnetron sputtering: A review on scientific and engineering state of the art

A variety of techniques are available enabling both invasive measurement, where the monitoring device is installed in the medium of interest, and noninvasive measurement where the monitoring system observes the medium of interest remotely. In this article we review the general techniques available, as well as specific instruments for particular applications. The issues of measurement criteria including accuracy, thermal disturbance and calibration are described. Based on the relative merits of different techniques, a guide for their selection is provided.

Review of temperature measurement

Room temperature spin polarized injection in organic semiconductor

A nonresonant microwave absorption has been observed at fields below the thermodynamic critical field, H/sub c//sub 1//sup (//sup T//sup )/, in the new copper oxide superconductors. This is associated with flux slippage and allows an estimation of the average area of the uniform phase in the superconducting glass state.

Low-field microwave absorption in the superconducting copper oxides

Growth mechanisms of poly-crystalline thin films, P. Barna and M. Adamik the SQUID magnetometer - an application of thin film superconductors, M.S. Colclough present status of the thin film industry, M. Croset energetic condensation during thin film growth, J. Cuomo characterization of thin films by spectroscopic ellipsometry, B. Drevillon organizational aspects in Langmuir Blodgett thin films, P. Ganguly heteroepitaxy of stable and unstable Fe silicides, H. von Kanel et al optoelectronic thin film devices with conjugated polymers and oligomers, G. Leising bombardment stabilization of c-BN, R. Messier et al pulsed electron beam ablation, G. Muller and C. Schultheiss thin films for large area electronics, D. Pribat et al XRD line broadening and texture analysis of thin films, P. Scardi self-polarization nature of ferro-electric thin films, I.M. Sem et al fundamental properties and developments of metallic and semiconducting thin film nanoparticles, A. Stella orientation-controlled organic thin films, H. Yanagi.

Science and technology of thin films

The Raman spectra of the charge-ordered manganite ${\mathrm{Pr}}_{0.65}{\mathrm{Ca}}_{0.35}{\mathrm{MnO}}_{3}$ were studied as functions of temperature and excitation energy and compared to magnetic moment and electrical conductivity behaviors. Both the charge ordering ( ${T}_{\mathrm{co}}\ensuremath{\approx}225\mathrm{K}$) and the antiferromagnetic transitions ( ${T}_{N}\ensuremath{\approx}175\mathrm{K}$) affect the spectral shape and intensity, indicating strong charge-lattice and spin-lattice couplings. Below ${T}_{\mathrm{co}}$ a transition from dynamic Jahn-Teller distortions to a collective static distortion takes place. A change of the spectra is observed on increasing the excitation energy above 2.5 eV and it is attributed to a resonant polaron excitation.

Francesco Cino Matacotta

Papers

Room temperature spin polarized injection in organic semiconductor

Low-field microwave absorption in the superconducting copper oxides

Science and technology of thin films

Jahn-teller dynamics in charge-ordered manganites from raman spectroscopy

Infrared photoinduced absorption in the YBa2Cu3O7−y high Tc superconducting system