| 1. |
- Ferrari, A. C., et al.
(författare)
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Science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems
- 2015
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Ingår i: Nanoscale. - : Royal Society of Chemistry (RSC). - 2040-3372 .- 2040-3364. ; 7:11, s. 4598-4810
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Tidskriftsartikel (refereegranskat)abstract
- We present the science and technology roadmap for graphene, related two-dimensional crystals, and hybrid systems, targeting an evolution in technology, that might lead to impacts and benefits reaching into most areas of society. This roadmap was developed within the framework of the European Graphene Flagship and outlines the main targets and research areas as best understood at the start of this ambitious project. We provide an overview of the key aspects of graphene and related materials (GRMs), ranging from fundamental research challenges to a variety of applications in a large number of sectors, highlighting the steps necessary to take GRMs from a state of raw potential to a point where they might revolutionize multiple industries. We also define an extensive list of acronyms in an effort to standardize the nomenclature in this emerging field.
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| 2. |
- van den Berg, J. J., et al.
(författare)
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Spin transport in epitaxial graphene on the C-terminated (000(1)over-bar)-face of silicon carbide
- 2016
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Ingår i: Applied Physics Letters. - : AMER INST PHYSICS. - 0003-6951 .- 1077-3118. ; 109:1, s. 012402-
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Tidskriftsartikel (refereegranskat)abstract
- We performed a temperature dependent study of the charge and spin transport properties of epitaxial graphene on the C-terminated (000 (1) over bar) face of silicon carbide (SiC), a system without a carbon buffer layer between the graphene and the SiC. Using spin Hanle precession in the nonlocal geometry, we measured a spin relaxation length of lambda(S) = 0.7 lm at room temperature, lower than in exfoliated graphene. We show that the charge and spin diffusion coefficient, D-C and D-S, respectively, increasingly deviate from each other during electrical measurements up to a difference of a factor 4. Thus, we show that a model of localized states that was previously used to explain D-C not equal D-S, can also be applied to epitaxial graphene systems without a carbon buffer layer. We attribute the effect to charge trap states in the interface between the graphene and the SiC. Published by AIP Publishing.
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| 3. |
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| 4. |
- Dash, Saroj Prasad, 1975, et al.
(författare)
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Electric field effects on spin accumulation in Nb-doped SrTiO3 using tunable spin injection contacts at room temperature
- 2014
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 104:21
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Tidskriftsartikel (refereegranskat)abstract
- We report on features in charge transport and spin injection in an oxide semiconductor, Nb-doped SrTiO3. This is demonstrated using electrically tunable spin injection contacts which exploit the large electric field at the interface and its interplay with the relative permittivity of the semiconductor. We realize spin accumulation in Nb-doped SrTiO3 which displays a unique dependence of the spin lifetime with bias polarity. These findings suggest a strong influence of the interface electric field on the charge transport as well as on spin accumulation unlike in conventional semiconductors and opens up promising avenues in oxide spintronics.
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| 5. |
- Sharma, S., et al.
(författare)
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Anisotropy of spin polarization and spin accumulation in Si/Al2O3/ferromagnet tunnel devices
- 2012
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 86:16
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Tidskriftsartikel (refereegranskat)abstract
- The contribution of the spin accumulation to tunneling anisotropy in Si/Al2O3/ferromagnet devices was investigated. Rotation of the magnetization of the ferromagnet from in-plane to perpendicular to the tunnel interface reveals a tunneling anisotropy that depends on the type of the ferromagnet (Fe or Ni) and on the doping of the Si (n or p type). Analysis shows that different contributions to the anisotropy coexist. Besides the regular tunneling anisotropic magnetoresistance, we identify a contribution due to anisotropy of the tunnel spin polarization of the oxide/ferromagnet interface. This causes the spin accumulation to be anisotropic, i.e., dependent on the absolute orientation of the magnetization of the ferromagnet.
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| 6. |
- Sharma, S., et al.
(författare)
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Anomalous scaling of spin accumulation in ferromagnetic tunnel devices with silicon and germanium
- 2014
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Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 89:7
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Tidskriftsartikel (refereegranskat)abstract
- The magnitude of spin accumulation created in semiconductors by electrical injection of spin-polarized electrons from a ferromagnetic tunnel contact is investigated, focusing on how the spin signal detected in a Hanle measurement varies with the thickness of the tunnel oxide. An extensive set of spin-transport data for Si and Ge magnetic tunnel devices reveals a scaling with the tunnel resistance that violates the core feature of available theories, namely, the linear proportionality of the spin voltage to the injected spin current density. Instead, an anomalous scaling of the spin signal with the tunnel resistance is observed, following a power law with an exponent between 0.75 and 1 over 6 decades. The scaling extends to tunnel resistance values larger than 10(9) Omega mu m(2), far beyond the regime where the classical impedance mismatch or back flow into the ferromagnet play a role. This scaling is incompatible with existing theory for direct tunnel injection of spins into the semiconductor. It also demonstrates conclusively that the large spin signal does not originate from two-step tunneling via localized states near the oxide/semiconductor interface. Control experiments show that spin accumulation in localized states within the tunnel barrier or artifacts are also not responsible. Altogether, the scaling results suggest that, contrary to all existing descriptions, the spin signal is proportional to the applied bias voltage, rather than the (spin) current.
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