Possible existence of a new type of left-handed materials in coupled ferromagnetic bilayer films

Unique properties of microwave in interlayer exchange-coupled trilayer ferromagnetic films associated with negative imaginary part of permeability

“…It is also found that the permeability of trilayer (or multilayer) film may be remarkably influenced by IEC [24][25][26][27]. For instance, in trilayer ferromagnetic film, the imaginary part of permeability of one ferromagnetic layer is unusually smaller than zero near resonance frequency of optic mode [27], i.e., the ferromagnetic layer may be taken as an active medium, and used to demonstrate unique electromagnetic properties predicted previously [13][14][15].…”

“…(2a) and (2b) based on the simple forward difference method with a time step of 10 À3 ns, which is sufficiently small to avoid numerical instability. Finally, the elements m ixx of permeability tensor of the ith ferromagnetic layer are defined by [14,27] …”

“…Left-handed material (LHM) has been received much attention due to its highly unusual electromagnetic properties and promise for new applications [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. In a paper published in 1968 [1], Veselago predicted that, in the medium having simultaneously negative (real parts of) permeability and permittivity, triple of vectors of electric field E * , magnetic field H * , and wave vector Reðk * Þ of electromagnetic wave (EMW) form a left-handed orthogonal set.…”

“…On the other hand, it is found that metamaterials may hold negative imaginary part of either effective permeability or effective permittivity [11,12]. In addition, the active media are proposed as a new type of LHM, and a lot of unique electromagnetic properties of LHM made of active media have been theoretically predicted [13][14][15]. However, the feasible active LHMs are still scarce.…”

Coupling of microwave magnetic dynamics in thin ferromagnetic films to stripline transducers in the geometry of the broadband stripline ferromagnetic resonance

“…The microwave conductivity contribution to the stripline broadband ferromagnetic resonance (FMR) response of highly-conducting (metallic) magnetic multilayers and nanostructures of sub-skin-depth thicknesses has attracted significant attention in recent years [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. It has been shown that these effects are important when the microwave magnetic field is incident on only one of the two surfaces of a planar metallic material (see e.g.…”