AndyJP
Subscriber
>Yes, I realize the limitations of HFSS regarding pinning and modes, but in certain regimes the magnetostatic approximation is still good, and that's what I'm interested in.nHow can you be sure? The band is fine. But without certainty in pinning, the mode can be wrong; so the impedance will also be wrong. And you are interested particularly in impedance.n>do you mean cut the film width at 45 degrees (taper)?nSorry, I am not doing film research for many years and lost some of my paper folders. But I can insure you, that is a common practice... it was in 90s.nActually, I am astonished how many decorated physicists do not know this old trick; I've seen it at MMM sympo where a professor was explaining it as his new invention, and we could not understand each other when I asked, so, what's new about that?nI guess, this effect was discovered when early researchers used shorter strips cut from the edge of 3-4 GGG waffers; so it came naturally without any effort.n>What do you mean I can't put them in project variable formulation but only in the material editor?nWell, it seems I was wrong, or the feature was introduced lately, so I missed it. I had an impression that any constant in the project variables is evaluated at runtime in the context and the scope of the model editor, with the global scope $. So defining a primitive with a vertex (2mm +X-Z^2, 4mm, sqrt(Y))... is really insanen   [error] Part Box1: Operation CreateBox uses intrinsic variable X. However, intrinsic variables cannot be used in this context. nThat's what I thought. But it seems like the project variable is not just calculated at runtime, but may be stored and used as a metacode, where XYZ are actually some smart objects available to other tools.nThis is amaizing since no prefix like $, and no evaluating function like getc_oordinate_X() are used.nSo, at your place I would just try defining the function in the material editor (in its scope), avoiding accessing XYZ objects from the project var editor. And see what happens; will it be different or the same.n>because the response of the transducer greatly changes your ability to launch spin waves efficientlynThere is an equivalent circuit with the transducer, and the load impedance of the spin wave mode. The latter is a real value, a resistor. It may be calculated analytically using https://link.springer.com/article/10.1007/BF00941342 (sorry, I have it in Russian scans only); there should be translations or equivalent works in English from Patton, Shirinivasyan, Ishak, Stashkevich or other big people from the spin-wave club. The current strip models are simple like in https://www.amazon.com/Magnetization-Oscillations-Waves-Alexander-Gurevich/dp/0849394600, for coplanar, it is more complicated, but I don't think there is no solution ready for use.... And I never thought that a coplanar may be better for launching a spin-wave. A micro-wire should have the widest band. And an array of wires is easier to control/design.nThe worst part of coplanar... you treat the spin-wave at um scale, but the coplanar works at mm scale. So from the position of spin wave, you excite it in non-shielded film, but it propagates then in a shielded film. So there is a transition with different modes and impedances on the edge of the CPW ground-plane. Therefore the problem is more than just a radiation impedance.n>Are you saying that then in my example of $aa, it does not have units of 1/mmnI am not saying that, but it happens quite often, and I personally check the conversions with a dummy box coordinates, or use excessive formulation with depersonification of variables first, then multiplying by the unit last.n