Tubular Geometries

Experimental Observation of Flat Bands in One-Dimensional Chiral Magnonic Crystals

“…31,32 A frequency nonreciprocity can also originate from any symmetry-breaking mechanism along the thickness, such as different anisotropies at the bottom and top surfaces, 33 magnetization grading, 34 and dipolar coupling in bilayers 35−37 and curved surfaces. 38,39 However, such effects are negligible in ultrathin films.…”

“…In the past decade, the research field of magnonics has rapidly grown due to its potential for the development of innovative low-energy computing devices, where spin waves (SWs), the collective excitations of electron spins, are used to carry and process information. − Progress in this field mainly relies on the capability to control and manipulate the SW propagation, for the implementation of SW-based devices with unprecedented functionalities in information and communication technologies. − In this context, the exploitation of the interfacial Dzyaloshinskii–Moriya interaction (i-DMI), − namely the antisymmetric exchange interaction arising at the interface of a ferromagnetic film and a heavy-metal substrate with high spin–orbit coupling, − can represent an effective method for achieving a nonreciprocal SW propagation, opening the way toward unidirectional devices such as insulators and diodes for nanomagnonic circuits. − The nonreciprocal magnonic propagation, induced by the presence of i-DMI, has been primarily used to quantify the i-DMI strength, D , in continuous metallic films and multilayers. − In this respect, a small i-DMI has also been observed in magnetic garnet systems in contact with heavy metals, − which are auspicious materials for magnonic applications due to their low damping. Nevertheless, typical values of the i-DMI strength are still 2 orders of magnitude smaller than for conventional ferromagnets. , A frequency nonreciprocity can also originate from any symmetry-breaking mechanism along the thickness, such as different anisotropies at the bottom and top surfaces, magnetization grading, and dipolar coupling in bilayers − and curved surfaces. , However, such effects are negligible in ultrathin films.…”