Do you want to publish a course? Click here

Long Range Triplet Josephson Current and $0-pi$ Transition in Tunable Domain Walls

186   0   0.0 ( 0 )
 Added by Andreas Bill
 Publication date 2013
  fields Physics
and research's language is English




Ask ChatGPT about the research

The order parameter of superconducting pairs penetrating an inhomogeneous magnetic material can acquire a long range triplet component (LRTC) with non-zero spin projection. This state has been predicted and generated recently in proximity systems and Josephson junctions. We show using an analytically derived domain wall of an exchange spring how the LRTC emerges and can be tuned with the twisting of the magnetization. We also introduce a new kind of Josephson current reversal, the triplet $0-pi$ transition, that can be observed in one and the same system either by tuning the domain wall or by varying temperature.



rate research

Read More

463 - M. Houzet , A. I. Buzdin 2007
We study the Josephson current through a ferromagnetic trilayer, both in the diffusive and clean limits. For colinear (parallel or antiparallel) magnetizations in the layers, the Josephson current is small due to short range proximity effect in superconductor/ferromagnet structures. For non colinear magnetizations, we determine the conditions for the Josephson current to be dominated by another contribution originating from long range triplet proximity effect.
Recent experimental breakthrough in magnetic Weyl semimetals have inspired exploration on the novel effects of various magnetic structures in these materials. Here we focus on a domain wall structure which connects two uniform domains with different magnetization directions. We study the topological superconducting state in presence of an s-wave superconducting pairing potential. By tuning the chemical potential, we can reach a topological state, where a chiral Majorana mode or zero-energy Majorana bound state is localized at the edges of the domain walls. This property allows a convenient braiding operation of Majorana modes by controlling the dynamics of domain walls.
We theoretically study the Josephson effect in a superconductor/normal metal/superconductor ({it S}/{it N}/{it S}) Josephson junction composed of $s$-wave {it S}s with {it N} which is sandwiched by two ferromagnetic insulators ({it F}s), forming a spin valve, in the vertical direction of the junction. We show that the 0-$pi$ transition of the Josephson critical current occurs with increasing the thickness of {it N} along the junction. This transition is due to the magnetic proximity effect (MPE) which induces ferromagnetic magnetization in the {it N}. Moreover, we find that, even for fixed thickness of {it N}, the proposed Josephson junction with the spin valve can be switched from $pi$ to 0 states and vice versa by varying the magnetization configuration (parallel or antiparallel) of two {it F}s. We also examine the effect of spin-orbit scattering on the Josephson critical current and argue that the 0-$pi$ transition found here can be experimentally observed within the current nanofabrication techniques, thus indicating a promising potential of this junction as a 0-$pi$ switching device operated reversibly with varying the magnetic configuration in the spin valve by, e.g., applying an external magnetic field. %with the magnetization configuration in the spin valve. Our results not only provide possible applications in superconducting electronics but also suggest the importance of a fundamental concept of MPE in nanostructures of multilayer {it N}/{it F} systems.
A magnetic helix arises in chiral magnets with a wavelength set by the spin-orbit coupling. We show that the helimagnetic order is a nanoscale analog to liquid crystals, exhibiting topological structures and domain walls that are distinctly different from classical magnets. Using magnetic force microscopy and micromagnetic simulations, we demonstrate that - similar to cholesteric liquid crystals - three fundamental types of domain walls are realized in the helimagnet FeGe. We reveal the micromagnetic wall structure and show that they can carry a finite skyrmion charge, permitting coupling to spin currents and contributions to a topological Hall effect. Our study establishes a new class of magnetic nano-objects with non-trivial topology, opening the door to innovative device concepts based on helimagnetic domain walls.
343 - S. Hikino , S. Yunoki 2013
We theoretically study spin current through ferromagnet (F) in a Josephson junction composed of s-wave superconductors and two layers of ferromagnets. Using quasiclassical theory, we show that the long-range spin current can be driven by the superconducting phase difference without voltage drop. The origin of this spin current is due to spin-triplet Cooper pairs (STCs) formed by electrons of equal-spin, which are induced by proximity effect inside the F. We find that the spin current carried by the STCs exhibits long-range propagation in the F even where the Josephson charge current is practically zero. We also show that this spin current persists over a remarkably longer distance than the ordinary spin current carried by spin polarized conduction electrons in the F. Our results thus indicate the promising potential of Josephson junctions based on multilayer ferromagnets for spintronics applications with long-range propagating spin current.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا