Zero temperature coefficient collapse field magnetic bubbles with 1.8-µm diameter

Abstract

Small diameter (1.8 μm) bubbles with zero temperature coefficients of bubble collapse field H 0 and bubble strip-out field H 2 were obtained in (Y Sm Lu Ca) 3-x Gd x (Fe Ge) 5 O 12 garnets. Doping with a small amount of Gd (x = 0.35) reduces the temperature variation of the saturation induction 4πM s to -0.16 percent/°C. Consequently the variations of H 0 and H 2 are flat in a wide temperature range (-20\deg \sim 100\deg C), while the strip width w changes at the rate of -0.15 percent/°C. The dynamic properties are almost the same as those in the pure case (x = 0). The initial wall mobility μw is 400 cm/s/Oe, and the saturation velocity is 60 m/s. The temperature variation of several properties in films of this system was compared with the temperature variation of those in films of the (Y Sm Lu) 3-x Gd x (Fe Ga) 5 O 12 system. The Ca-Ge substituted system is more suited to supporting bubbles with zero temperature coefficient collapse field.