The failure of a silver nanowire (AgNW) random network due to high electric current density is described. The AgNW network breaks down as result of electromigration and Joule heating at junctions, which leads to destroyed interconnections between AgNWs. The AgNW network is not completely destroyed after breakdown, but instead is able to undergo multiple breakdowns after being cooled down, with increased resistance and reduced breakdown current density. The breakdown current density of AgNW network is J(max) = 25 A cm(-2) for a network with R(s) ~ 40 Ω sq(-1) outperforming a CuNW network. An effective electrical annealing method is demonstrated to decrease network resistance by 18% by periodically applying high current that is slightly lower than breakdown current with a period of 1 min for a few cycles.
We experimentally show the effect of enhanced spin-orbit and RKKY induced torques on the current-induced motion of a pair of domain walls (DWs), which are coupled antiferromagnetically in synthetic antiferromagnetic (SAF) nanowires. The torque from the spin Hall effect (SHE) rotates the Néel DWs pair into the transverse direction, which is due to the fact that heavy metals of opposite spin Hall angles are deposited at the top and the bottom ferromagnetic interfaces. The rotation of both DWs in non-collinear fashion largely perturbs the antiferromagnetic coupling, which in turn stimulates an enhanced interlayer RKKY exchange torque that improved the DW velocity. The interplay between the SHE-induced torque and the RKKY exchange torque is validated via micromagnetic simulations. In addition, the DW velocity can be further improved by increasing the RKKY exchange strength.
We performed temperature-dependent optical pump -THz emission measurements in Y3Fe5O12 (YIG)|Pt from 5 K to room temperature in the presence of an externally applied magnetic field. We study the temperature dependence of the spin Seebeck effect and observe a continuous increase as temperature is decreased, opposite to what is observed in electrical measurements where the spin Seebeck effect is suppressed as 0 K is approached. By quantitatively analysing the different contributions we isolate the temperature dependence of the spin-mixing conductance and observe features that are correlated to the bands of magnon spectrum in YIG.The longitudinal spin Seebeck effect (LSSE) 1 describes the transfer of a spin current from a magnetic insulator driven by a temperature gradient. An adjacent heavy metal (HM) layer with large spin orbit coupling is typically used to convert the spin current into an electrical signal via the inverse spin Hall effect (ISHE). 2,3 The LSSE has been measured in a variety of different materials such as ferromagnets 1,4,5 , anti-ferromagnets 6,7 and paramagnets. 8 Magnetic insulators (MI) such as Y3Fe5O12 (Yttrium Iron Garnet -YIG) are particularly interesting for studies on the LSSE since the absence of electron charge transport allows the roles of magnons and phonons to be identified in the spin transfer. 1,3,9,10 Temperature, thickness and magnetic field dependence studies have contributed to a phenomenological picture of magnon-driven spin current. [11][12][13][14][15] A temperature gradient across the magnetic insulator thickness leads to the diffusion of thermal magnons that accumulate at the interface with the HM. 16,17 The temperature dependence of the magnon propagation length m results in a characteristic peak in the SSE signal at low temperature when the thickness of the MI is comparable to m . 12 Low frequency magnons play a dominant role due to their large population and
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