192 research outputs found
Smart Tools for Smart Applications: New Insights into Inorganic Magnetic Systems and Materials
This Special Issue, consisting of four reviews and three research articles, presents some of the recent advances and future perspectives in the field of magnetic materials and systems, which are designed to meet some of our current challenge
Unidirectional spin Hall magnetoresistance in ferromagnet/normal metal bilayers
Magnetoresistive effects are usually invariant upon inversion of the
magnetization direction. In noncentrosymmetric conductors, however, nonlinear
resistive terms can give rise to a current dependence that is quadratic in the
applied voltage and linear in the magnetization. Here we demonstrate that such
conditions are realized in simple bilayer metal films where the spin-orbit
interaction and spin-dependent scattering couple the current-induced spin
accumulation to the electrical conductivity. We show that the longitudinal
resistance of Ta|Co and Pt|Co bilayers changes when reversing the polarity of
the current or the sign of the magnetization. This unidirectional
magnetoresistance scales linearly with current density and has opposite sign in
Ta and Pt, which we associate with the modification of the interface scattering
potential induced by the spin Hall effect in these materials. Our results
suggest a route to control the resistance and detect magnetization switching in
spintronic devices using a two-terminal geometry, which applies also to
heterostructures including topological insulators
Sensing of DVB-T signals for white space cognitive radio systems
In cognitive radio networks, systems operating in digital television white spaces are particularly interesting for practical applications. In this paper, we consider single- antenna and multi-antenna spectrum sensing of real DVB-T signals under different channel conditions. Some of the most important algorithms are considered and compared, including energy detection, eigenvalue based techniques and methods exploiting OFDM signal knowledge. The obtained results show the algorithm performance and hierarchy in terms of ROC and detection probability under fixed false alarm rate, for different channel profiles in case of true DVB-T signals
Sensing of DVB-T signals for white space cognitive radio systems
In cognitive radio networks, systems operating in digital television white spaces are particularly interesting for practical applications. In this paper, we consider single- antenna and multi-antenna spectrum sensing of real DVB-T signals under different channel conditions. Some of the most important algorithms are considered and compared, including energy detection, eigenvalue based techniques and methods exploiting OFDM signal knowledge. The obtained results show the algorithm performance and hierarchy in terms of ROC and detection probability under fixed false alarm rate, for different channel profiles in case of true DVB-T signal
Spin communication over 30 m long channels of chemical vapor deposited graphene on SiO
We demonstrate a high-yield fabrication of non-local spin valve devices with
room-temperature spin lifetimes of up to 3 ns and spin relaxation lengths as
long as 9 m in platinum-based chemical vapor deposition (Pt-CVD)
synthesized single-layer graphene on SiO/Si substrates. The spin-lifetime
systematically presents a marked minimum at the charge neutrality point, as
typically observed in pristine exfoliated graphene. However, by studying the
carrier density dependence beyond n ~ 5 x 10 cm, via
electrostatic gating, it is found that the spin lifetime reaches a maximum and
then starts decreasing, a behavior that is reminiscent of that predicted when
the spin-relaxation is driven by spin-orbit interaction. The spin lifetimes and
relaxation lengths compare well with state-of-the-art results using exfoliated
graphene on SiO/Si, being a factor two-to-three larger than the best values
reported at room temperature using the same substrate. As a result, the spin
signal can be readily measured across 30 m long graphene channels. These
observations indicate that Pt-CVD graphene is a promising material for
large-scale spin-based logic-in-memory applications
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