Effects of Cr, CrV, and CrTi underlayers on magnetic, structural, and materials reliability properties of CoPt thin films

Abstract

Co 80 Pt 20 thin films on Cr, Cr80V20, or Cr90Ti10 underlayers were studied to improve the magnetic properties for permanent magnetic stabilization layer application in anistropic magnetoresistance/giant magnetoresistance devices. A significant improvement of nearly 15% in coercivity was achieved for CoPt films on CrTi underlayer, when compared to either Cr or CrV underlayer. X-ray diffraction pattern analysis showed that CrTi underlayer increased the intensity of CoPt (10.0) indicating enhanced crystallographic in-plane texture. With CrTi underlayer, CoPt coercivity increased linearly as Mrt was reduced from 4.3 to as low as 0.4 memu/cm2. The squareness and S* values started to drop sharply when the Mrt of CoPt film decreased to below 1.0 memu/cm2. In addition to 15% higher coercivity, another important property of CrTi/CoPt was that for CrTi underlayer thickness between 3 and 20 nm very little change in the coercivity, squareness, and S* of CoPt layer was observed. The CoPt films showed excellent corrosion resistance towards high humidity and good thermal stability up to 300 °C. The CoPt films with the underlayer of CrTi and CrV showed slightly less corrosion resistance towards industrial pollutants than those with no underlayer and Cr underlayer.

Magnetic properties of ion beam deposited CoPt and CoCrPt films for hard bias application in high density magnetoresistive heads

“…This confirms that some of the grains have their c-axis gradually tilting away from the film surface with increasing &,. A high I-& value is obviously associated with a high CO( 1 OTO)/Co(OO02) difiaction intensity ratio, which is consistent with the previous investigation[ 1], [2]. The CO( 1010) preferred orientation favors in the growth of a CoCrPt film when it grows on a Cr layer with (21 1) orientation, as previously reported by Nakamura et a1.…”

“…CdCoPt films exhibit values of H, about 30% higher than those for Cr/CoCrPt films for a given Mfi. These H, values are also much higher than those previously reported from the conventional PVD films [2]. The saturation magnetization of CoPt films is 830 emu/cm3, about 40% higher than that of CoCrPt films [l].…”

“…3(b). The increase in H, with increasing is accompanied by an improvement in in-plane c-axis orientation, as inferred by an enhancement in (IOTO) texture along the film growth direction [1], [2]. A maximum in H, is reached at &,.=400A.…”

Ordering enhancement of Cu underlayer on CoPt thin films

“…Some authors have tried to developed FePt or CoPt granular films by using the underlayers of Ag, Cr, MgO, and SiO 2 , etc [9][10][11][12]. However, the annealing temperature for the ordering transformation is too high for the application of recording media.…”

Physics and Design of Hard Disk Drive Magnetic Recording Read Heads

“…These materials have a hexagonal close packed (hcp) crystal structure. When deposited on body-centered cubic (bcc) seed layers such as Cr or Cr alloys [59], they will grow with their magnetic easy axis, the crystallographic c-axis, in the plane, so that the hard-bias magnetization is pointing at the free layer. The hard-bias field, which scales with the hard-bias remanent magnetization-thickness product (Mr*t), is penetrating the free layer and is stabilizing it in a direction perpendicular to the reference layer.…”