Green's function formalism for nonlocal elliptical magnon transport

We develop a nonequilibrium Green's function formalism to study magnonic spin transport through strongly anisotropic ferromagnetic insulator contacted by metallic leads. model the as finite-sized one-dimensional chain, with contacts at first and last sites that inject detect in form of magnons. In presence anisotropy, these magnons become elliptically polarized, conservation is broken. show this gives rise novel parasitic conductance, which becomes dominant high anisotropy. Moreover, state ferromagnet squeezed high-anisotropy regime. squeezing may be globally reduced application local bias.