series of environmental conditions to improve reproducibility
of results.
Topographical information regarding the physical structure
of the heads was obtained using a ThermoMicroscope
AFM operated in contact mode. Image enhancement was
restricted to the use of shading and levelling algorithms.
Various methods for measuring PTR using the AFM have
been employed, usually dictated by the software available
with the instrument being used. The method [14] used for
this work required that a 0th order flatten be applied to the
raw image. Secondly a 2nd order XY plane fit auto on
the AlTiC surface. The profile of the head generated by the
AFM has two curvature components: (1) the form of the
head; (2) the bow created by the AFM scanner. If the tape is
assumed to follow the form of the head, then the AlTiC TBS
on both sides of the head can be used to generate a profile of
surface that can be subtracted from the entire image. This
routine not only subtracts the head form, but also subtracts
the scanner bow (which is generally uniform). A second
order plane fit provides the ability to subtract a sphere/
parabola from the image. The scan direction was the same as
the tape cycling direction during acquisition of the AFM
image. A scan rate of 0.4 Hz was used and 512 data points
were collected along each of the 512 scan lines. Great care
was taken in obtaining raw data from AFM. All the PTR
values reported here is the six elements average values. The
standard error in PTR values is less than 2 nm.
Auger electron spectroscopy (AES) was used to analyse
the heads. AES enabled elemental compositions to be
determined at different points on the surface of the heads
with better than 1 mm resolution. Further chemical examination
of the tape samples was conducted by means of Xray
photoelectron spectroscopy (XPS) for the virgin tape
and worn tape in different environment conditions. Both
analyses were conducted in a VG ESCALAB 200D electron
spectrometer equipped with a hemispherical sector energy
analyser. Mg Ka X-radiation was employed for the XPS
examination, at source excitation energy of 15 keV and
emission current of 20 mA. Analyser pass energy of 20 eV
with step size of 0.1 eV and dwell time of 100 ms was used
throughout. The area of XPS analysis was chosen to be
1 mm2 for each analysis of tape samples. The analysis area
was chosen in the middle area of the tape.
Relative atomic concentrations were calculated for each
sample from the intensities of the major photoelectron or
Auger spectral lines by means of codes incorporated in the
VG Eclipse V2.0 instrument data system. The base pressure
within the spectrometer during examinations was always
better than 5!10K7 Pa and this ensured that all signals
recorded were from the sample surface.
Olympus optical microscopy is used to examine the head
surface. There is an Olympus digital camera fitted on the
optical microscopy. So the images of the head could be
taken and stored in the computer. The maximum magnification
of the image is 400 times, it is clearly seen the 1 mm
object, such as the grains of the ceramic and the pole and
shared pole of the heads.