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Coulomb blockade anisotropic magnetoresistance: Singleelectronics meets spintronics  [PDF]
J. Wunderlich,T. Jungwirth,B. Kaestner,A. C. Irvine,K. Wang,N. Stone,U. Rana,A. D. Giddings,A. B. Shick,C. T. Foxon,R. P. Campion,D. A. Williams,B. L Gallagher
Physics , 2006,
Abstract: Single-electronics and spintronics are among the most intensively investigated potential complements or alternatives to CMOS electronics. Single-electronics, which is based on the discrete charge of the electron, is the ultimate in miniaturization and electro-sensitivity. Spintronics, which is based on manipulating electron spins,delivers high magneto-sensitivity and non-volatile memory effects. So far, major developments in the two fields have followed independent paths with only a few experimental studies of hybrid single-electronic/spintronic devices. Intriguing new effects have been discovered in such devices but these have not, until now, offered the possibility of useful new functionalities. Here we demonstrate a device which shows a new physical effect, Coulomb blockade anisotropic magnetoresistance, and which offers a route to non-volatile, low-field, and highly electro- and magneto-sensitive operation. Since this new phenomenon reflects the magnetization orientation dependence of the classical single-electron charging energy it does not impose constraints on the operational temperature associated with more subtle quantum effects, such as resonant or spin-coherent tunneling.
Flexible isotopy classification of flexible links  [PDF]
Johan Bj?rklund
Mathematics , 2012,
Abstract: In this paper we define and study flexible links and flexible isotopy in projective space. Flexible links are meant to capture the topological properties of real algebraic links. We classify all flexible links up to flexible isotopy using Ekholms interpretation of Viros encomplexed writhe.
Spintronics?  [PDF]
M. I. Dyakonov
Physics , 2004,
Abstract: This is a brief review of spin physics in semiconductors, as well as of the historic roots of the recent very active research of spin-related phenomena. The perspectives of "spintronics" are also discussed.
Spintronics with NSN Junction of one-dimensional quantum wires : A study of Pure Spin Current and Magnetoresistance  [PDF]
Sourin Das,Sumathi Rao,Arijit Saha
Physics , 2007, DOI: 10.1209/0295-5075/81/67001
Abstract: We demonstrate possible scenarios for production of pure spin current and large tunnelling magnetoresistance ratios from elastic co-tunnelling and crossed Andreev reflection across a superconducting junction comprising of normal metal-superconductor-normal metal, where, the normal metal is a one-dimensional interacting quantum wire. We show that there are fixed points in the theory which correspond to the case of pure spin current. We analyze the influence of electron-electron interaction and see how it stabilizes or de-stabilizes the production of pure spin current. These fixed points can be of direct experimental relevance for spintronics application of normal metal-superconductor-normal metal junctions of one-dimensional quantum wires. We also calculate the power law temperature dependence of the crossed Andreev reflection enhanced tunnelling magnetoresistance ratio for the normal metal-superconductor-normal metal junction.
Charge-transfer polaron induced negative differential resistance and giant magnetoresistance in organic spintronics: A Su-Schrieffer-Heeger model study  [PDF]
J. H. Wei,S. J. Xie,L. M. Mei,J. Berakdar,YiJing Yan
Physics , 2005, DOI: 10.1088/1367-2630/8/5/082
Abstract: Combining the Su-Schrieffer-Heeger model and the non-equilibrium Green's function formalism, we investigate the negative differential resistance effect in organic spintronics at low temperature and interprete it with a self-doping picture. A giant negative magnetoresistance exceeding 300% is theoretically predicted as the results of the negative differential resistance effects.
Perspectives in spintronics: magnetic resonant tunneling, spin-orbit coupling, and GaMnAs  [PDF]
C. Ertler,A. Matos-Abiague,M. Gmitra,M. Turek,J. Fabian
Physics , 2008, DOI: 10.1088/1742-6596/129/1/012021
Abstract: Spintronics has attracted wide attention by promising novel functionalities derived from both the electron charge and spin. While branching into new areas and creating new themes over the past years, the principal goals remain the spin and magnetic control of the electrical properties, essentially the I-V characteristics, and vice versa. There are great challenges ahead to meet these goals. One challenge is to find niche applications for ferromagnetic semiconductors, such as GaMnAs. Another is to develop further the science of hybrid ferromagnetic metal/semiconductor heterostructures, as alternatives to all-semiconductor room temperature spintronics. Here we present our representative recent efiorts to address such challenges. We show how to make a digital magnetoresistor by combining two magnetic resonant diodes, or how introducing ferromagnetic semiconductors as active regions in resonant tunneling diodes leads to novel efiects of digital magnetoresistance and of magnetoelectric current oscillations. We also discuss the phenomenon of tunneling anisotropic magnetoresistance in Fe/GaAs junctions by introducing the concept of the spin-orbit coupling field, as an analog of such fields in all-semiconductor junctions. Finally, we look at fundamental electronic and optical properties of GaMnAs by employing reasonable tight-binding models to study disorder efiects.
Tunneling Anisotropic Magnetoresistance in Co/AlOx/Au Tunnel Junctions  [PDF]
R. S. Liu,L. Michalak,C. M. Canali,L. Samuelson,H. Pettersson
Physics , 2008, DOI: 10.1021/nl072985p
Abstract: We observe spin-valve-like effects in nano-scaled thermally evaporated Co/AlOx/Au tunnel junctions. The tunneling magnetoresistance is anisotropic and depends on the relative orientation of the magnetization direction of the Co electrode with respect to the current direction. We attribute this effect to a two-step magnetization reversal and an anisotropic density of states resulting from spin-orbit interaction. The results of this study points to future applications of novel spintronics devices involving only one ferromagnetic layer.
1500-fold Tunneling Anisotropic Magnetoresistance in a (Ga,Mn)As stack  [PDF]
C. Rüster,C. Gould,T. Jungwirth,J. Sinova,G. M. Schott,R. Giraud,K. Brunner,G. Schmidt,L. W. Molenkamp
Physics , 2004, DOI: 10.1103/PhysRevLett.94.027203
Abstract: We report the discovery of a super-giant tunneling anisotropic magnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure. The effect arises from a strong dependence of the electronic structure of ferromagnetic semiconductors on the magnetization orientation rather than from a parallel or antiparallel alignment of the contacts. The key novel spintronics features of this effect are: (i) both normal and inverted spin-valve like signals; (ii) a large non-hysteretic magnetoresistance for magnetic fields perpendicular to the interfaces; (iii) magnetization orientations for extremal resistance are, in general, not aligned with the magnetic easy and hard axis. (iv) Enormous amplification of the effect at low bias and temperatures.
Superconducting Spintronics  [PDF]
Jacob Linder,Jason W. A. Robinson
Physics , 2015, DOI: 10.1038/nphys3242
Abstract: Traditional studies that combine spintronics and superconductivity have mainly focused on the injection of spin-polarized quasiparticles into superconducting materials. However, a complete synergy between superconducting and magnetic orders turns out to be possible through the creation of spin-triplet Cooper pairs, which are generated at carefully engineered superconductor interfaces with ferromagnetic materials. Currently, there is intense activity focused on identifying materials combinations that merge superconductivity and spintronics to enhance device functionality and performance. The results look promising: it has been shown, for example, that superconducting order can greatly enhance central effects in spintronics such as spin injection and magnetoresistance. Here, we review the experimental and theoretical advances in this field and provide an outlook for upcoming challenges in superconducting spintronics.
Oxide spintronics  [PDF]
Manuel Bibes,Agnes Barthelemy
Physics , 2007, DOI: 10.1109/TED.2007.894366
Abstract: Concomitant with the development of metal-based spintronics in the late 1980's and 1990's, important advances were made on the growth of high-quality oxide thin films and heterostructures. While this was at first motivated by the discovery of high-temperature superconductivity in perovskite Cu oxides, this technological breakthrough was soon applied to other transition metal oxides, and notably mixed-valence manganites. The discovery of colossal magnetoresistance in manganite films triggered an intense research activity on these materials, but the first notable impact of magnetic oxides in the field of spintronics was the use of such manganites as electrodes in magnetic tunnel junctions, yielding tunnel magnetoresistance ratios one order of magnitude larger than what had been obtained with transition metal electrodes. Since then, the research on oxide spintronics has been intense with the latest developments focused on diluted magnetic oxides and more recently on multiferroics. In this paper, we will review the most important results on oxide spintronics, emphasizing materials physics as well as spin-dependent transport phenomena, and finally give some perspectives on how the flurry of new magnetic oxides could be useful for next-generation spintronics devices.
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