Measurements of the exchange stiffness of YIG films using broadband ferromagnetic resonance techniques

Abstract

Measurements of the exchange stiffness $D$ and the exchange constant $A$ of\nYttrium Iron Garnet (YIG) films are presented. The YIG films with thicknesses\nfrom 0.9 $\\mu$m to 2.6 $\\mu$m were investigated with a microwave setup in a\nwide frequency range from 5 to 40 GHz. The measurements were performed when the\nexternal static magnetic field was applied in-plane and out-of-plane. The\nmethod of Schreiber and Frait, based on the analysis of the perpendicular\nstanding spin wave (PSSW) mode frequency dependence on the applied out-of-plane\nmagnetic field, was used to obtain the exchange stiffness $D$. This method was\nmodified to avoid the influence of internal magnetic fields during the\ndetermination of the exchange stiffness. Furthermore, the method was adapted\nfor in-plane measurements as well. The results obtained using all methods are\ncompared and values of $D$ between $(5.18\\pm0.01) \\cdot 10^{-17}$T$\\cdot$m$^2$\nand $(5.34\\pm0.02) \\cdot 10^{-17}$ T$\\cdot$m$^2$ were obtained for different\nthicknesses. From this the exchange constant was calculated to be $A=(3.65 \\pm\n0.38)~$pJ/m.\n