Omnidirectional spin-wave nanograting coupler

Luis Lizardi

Metamaterials

! Photonic Crystals ! Light(photons)

! Magnonic Crystals ! Spin Waves(magnons)

uNot be observed in the nature

uPeriodic patterning at the nanoscale uControl!!

Magnonics and technology

! Current semiconductor technology

! SW in cellular nonlinear networks

! Low power consumption

! Source of short-wavelength SW

Some magnonic grating couplers

Py nanowire(green) and CoFeB(blue) 1D Device

Py(green) 2D Device

Some magnonic grating couplers

Py thin film with Co nanodisks BGC

CoFeB thin film with Py nanodisks BGC

and their specifications

Con campo Sin campo

Evidence of grating-coupler modes

! Angular dependence spin-wave spectroscopy and back-folded dispersion relation

Evidence of grating-coupler modes

! Excitation spectrum I(k) of a BCG with a =800 nm in a in-plane field.

Evidence of grating-coupler modes

! Isofrequency lines in reciprocal space(photonics v/s SWs) Kalinikos, B. A. & Slavin, A. N. Theory of dipole-exchange spin wave spectrum for ferromagnetic films with mixed exchange boundary conditions. J. Phys. C Solid State Phys. 19, 70137033 (1986).

o Pronounced anisotropy for SW o In-plane magnetic field H

Evidence of grating-coupler modes

! Angular dependence of spin-wave dispersion relations f(k)

SW emission in non high-symmetry directions

! Multidirectional SW detection for different BGCs

SWs for perpendicular magnetization

! 1.8 T applied perpendicular to the plane

! BGC with a = 800 nm

! Solid(dashed) arrows indicate resonance also seen in in-plane (only in out-og-plane)

Proposed device in magnon spintronic

Field dependent SW espectroscopy and SEM image of a BGC

Conclusions and Questions

! The NG method can be directly integrated on a chip

! Dont require electrical contacts to nanopillars

! Can generate plane wave with stable phase

! Works without restriction in both in-plane and out-of-plane fields(compared with NOs)

! The stable phase is relevant for operating CNNs