| Summary: | 碩士 === 輔仁大學 === 物理學系 === 84 === Epitaxial Co/Cr(Mo,V) thin films, bilayered films and
multilayers have been successfully grown on the MgO(100) and
MgO(110) substrates by molecularbeam epitaxy (MBE). The magnetic
and transport properties have been studied,especially emphasized
on the magnetic anisotropy and magnetoresistance. According to
the reflection high energy electron diffraction (RHEED)
patternsand x-ray diffraction (XRD) measurements,the
crystalstructure of the films depends on the orientation of the
buffer layer and substrate. The magnetic properties of all these
samples were studied by using a superconducting quantum
interference device (SQUID) magnetometer. The magnetoresistive
properties were measured by the standard four probe technique
between 10 K to 300 K. According to the above measurements
and analysis,the bilayered films and multilayers which have the
same structure of the same unit cells show the similar magnetic
anisotropy and magnetoresistance. For hcp-Co/Cr(211) bilayers
and multilayers grown on MgO(110),the enhancement of anisotropic
magnetoresistance (AMR) as high as 8~12% can be observed along
the easy axis(c axis) at 10 K. It explained why we can not see
obvious giant magnetoresistance (GMR) effect in Co/Cr multilayer
system and also provided one way to know the sources of
magnetoresistance.
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