Investigation of the growth of garnet films by liquid phase epitaxy
Liquid phase expitaxy was investigated to determine its applicability to fabricating magnetic rare earth garnet films for spacecraft data recording systems. Two mixed garnet systems were investigated in detail: (1) Gd-Y and (2) Eu-Yb-Y. All films were deposited on Gd3Ga5012 substrates. The uniaxial anisotropy of the Gd-Y garnets is primarily stress-induced. These garnets are characterized by high-domain wall mobility, low coercivity and modest anisotropy. Characteristic length was found to be relatively sensitive to temperature. The Eu-Yb-Y garnets exhibit acceptable mobilities, good temperature stability and reasonable quality factors. The uniaxial anisotropy of these garnets is primarily growth-induced. The system is well suited for compositional "tailoring" to optimize specific desirable properties. Liquid phase epitaxy can be used to deposit Gd3Ga5012 spacing layers on magnetic garnet films and this arrangement possesses certain advantages over more conventional magnetic filmspacing layer combinations. However, it cannot be used if the magnetic film is to be ion implanted.
Resonant Motion of Domain Walls in Yttrium Gadolinium Iron Garnets
The radio frequency (rf) susceptibility of a series of yttrium gadolinium iron garnets was investigated in the frequency range 40–160 MHz. Resonant behavior was observed for most compositions, and the effective mass of the domain walls and the Landau‐Lifshitz damping parameter were determined. The damping parameter was found to be approximately the same for the yttrium and gadolunium ions with the value λ ≃ 1.6×107 rad sec−1.
Domain Wall Dynamics Measured Using Cylindrical Domains
An experimental technique is presented for the measurement of the translational dynamic properties of a cylindrical domain held stable in a thin plate of uniaxial magnetic material by a bias field normal to the plate. A second field HROT, rotating in the plane of the plate at a frequency ω, saturates and rotates the magnetization in a circular Permalloy film parallel to and in close proximity with the plate. Interaction of the domain with the Permalloy disk pulls the domain underneath the edge of the disk and causes it to follow HROT around the circumference. The force driving the domain is proportional to the sine of the angle ψ by which the angular position of the domain lags behind HROT. For the rare‐earth orthoferrites, this drive force is balanced by a viscous drag proportional to ω and inversely proportional to wall mobility. For a sample of the mixed orthoferrite Sm0.55Tb0.45FeO3, measurements of ψ at frequencies up to 225 kHz by stroboscopic observation of the domain showed the linear dependence o...