Structural and Magnetic Features of Fe-Based Multilayers with Thick Non-Magnetic Layers
- PDF / 1,724,213 Bytes
- 5 Pages / 414.72 x 648 pts Page_size
- 102 Downloads / 174 Views
739 Mat. Res. Soc. Symp. Proc. Vol. 403 01996 Materials Research Society
Ar pressure was 0.3Pa. Film thickness was monitored by the quartz oscillation method. Deposition conditions were arranged so as to form well-defined columnar structures in an attempt to introduce structural inhomogenities in films during film deposition. Film structures were characterized by field-emission scanning electron microscopy (FE-SEM) mainly. Magnetic properties were measured using a vibrating sample magnetometer.
alnico magnet
v,
rotatable substrate holder
I
"~target shutter '~Ar
plasma 4-
gas
substrates
RESULTS AND DISCUSSION -- VU•
,l
•
Fe films prepared in this apparatus showed Fig. I Schematic diagram of a double a uniaxial magnetic anisotropy of about 2X fig.S atic dir of apdoubl 3 fing-target-type dc sputtering apparatus. in the film planes. A schematic 104Jim diagram of the parts arrangement and a typical surface morphology observed by FE-SEM are shown in Fig.2. Each column formed an asymmetric shape in the film plane as shown in Fig.2. The magnetic anisotropy in the film originated from such columnar structure. The magnetic field due to magnets did not influence the magnetic anisotropy in this preparation condition. The detailed relation between the magnetic anisotropy and the columnar structure has been discussed by Hoshi et al. [3]. The formation of asymmetric column in the film plane is due to the arrangement of the sputtering apparatus as shown in Fig.2. The sputtered particles are distributed conically around the target center. The sputtered particles or atoms are deposited on the substrate as a function of the incident angle. If substrate temperature is low enough compared to the melting point of the deposited metals, surface 145cm
a)
magnetic fiel'd magnets
b)
c) Fig.2 Schematic diagram of parts arrangement of sputtering apparatus and typical surface morphology observed by FE-SEM. This is the surface of Fe 500nm. Acceleration voltage was 5kV.
Fig.3 Typical surface morphology of Fe films observed by FE-SEM. The thicknesses of Fe films are a) 50nm, b) 80nm, c) 200nm.
740
diffusion is limited and the shadowing effect is dominant, resulting in the formation of the asymmetric columns [3]. The asymmetric column had long and short axes in the film plane. The direction along the long axis corresponded to that of the easy axis in the film plane. The direction of the short axis made an angle of 90 degrees to that of the long axis and corresponded to the direction of the hard axis. The lengths of the long and the short axis changed with increasing of film thickness as shown in Fig.3. Those are morphologies of surfaces of Fe films observed by FE-SEM for various film thicknesses. Here, we mention briefly our previous report [2, 4]. We investigated the dependence of coercivity on the structural features of b) Fe/Ag and Fe/Ta nonmagnetic layer multilayers. In that study, the Fe layers in Fe F layer 2 the multilayer were not
coupled
mag-
Fe
______-_
t nonmagnetic layer -netically because they nm etl were sep
Data Loading...
