Magnetoresistance and Magnetic Properties of Co(tCo)/Cu Multilayer Films
Conrad Rizal
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING, UNIVERSITY OF BRITISH COLUMBIA, VANCOUVER, BC, V6T-1Z4, CANADA
INTRODUCTION
EXPERIMENTAL PROCEDURES
EXPERIMENTAL RESULTS
MR RATIO vs. STRAIN
Research Background
The electroytic bath consisted
of CoSO4.7H2O, CuSO4.2H2O,
Na3C6H5O7, and NaCl.
● M-H Curves of the As-deposited Films
● M-H Curves of Strained Co/Cu
Multilayer Films
● Torque Measurement
● Co Layer Thickness Dependence of MR Ratio
● H Dependence of MR Ratio
● H Dependence of Magnetization Curves
● Relationship Between the MR
ratio and Strain
MR ratio and remnant magnetization as a function of strain.
Magnetoresistance Effect
Giant Magnetoresitance Effect
Cu buffer layers, each 15 nm
thick, were vapor deposited on the
polyamide substrate.
Magnetic Anisotropy
Purpose of the Experiment
Experimental Details
Pulse Electrodeposition
BACKGROUND
GENERATION OF MAGNETIC
ANISOTROPY
Oblique Angle Incidence
Magnetic Annealing
Application of Magnetic Field
Introduction to Strain
The electrical resistivity was measured by the four-probe method.
The magnetic field dependence of
MR ratio was examined by varying
the relative direction between the
field, H, and current, I.
The composition of Co and Cu in
the film was determined by energy
dispersive X-ray analysis.
MR RATIO AS A FUNCTION OF
THE Co LAYER THICKNESS
MAGNETIZATION CURVES: ASDEPOSITED SAMPLE
CONCLUSIONS
Magnetization curves were measured using a vibrating sample
magnetometer (VSM).
MAGNETIC
FIELD
DENCE OF MR RATIO
MAGNETORESISTANCE
EFFECT IN MULTILAYER FILMS
Occurs in coupled magnetic layers.
MAGNETIZATION
STRAINED SAMPLE
The resistance (in magnetic field)
depends on the relative orientation
of the magnetization.
CURVES:
A SET OF MAGNETIZATION
CURVES AS A FUNCTION OF
Co LAYER THICKNESS (AT THE
CONSTANT STRAIN VALUE)
OBJECTIVES
GIANT MAGNETORESISTANCE
EFFECT IN MANETIC MULTILAYER FILMS
The figure below shows the GMR
effect in magnetic multilayer films
(a) To grow nano-order Co/Cu
multilayer films (on a polyamide
substrate) and apply strain to induce magnetic anisotropy, and (b)
To study electrical and magnetic
properties.
DEPEN-
A series of studies on the electrochemically grown ferromagnetic Co(tCo)/Cu multilayer grown
on the polyamide substrate (1.69
cm2) is presented. The induced
uniaxial magnetic anisotropy was
observed because of the effect of
strain in all the multilayer films.
The multilayer [Co 1.0 nm /Cu 1.5
nm]50 showed a minimum hysteresis loss. The MR ratio was ~3.4%
at 1 kOe. A remarkable difference
of MR ratio was observed, corresponding to the orientation of magnetization curves.
These Co/Cu multilayer films with
remarkable anisotropy properties
have potential application as magnetic sensors.
ACKNOWLEDGEMENTS
PULSE ELECTRODEPOSITION
METHOD
TORQUE MEASUREMENT
A sample in the form of a disc was
suspended in the magnetic field.
A torque curve as a function of the
measurement angle was derived.
The author acknowledges Prof.
Emeritus Ueda, Yuji of Department
of Electrical and Electronic Engineering, Muroran Institute of Technology, Hokkaido, Japan for valuable discussions. This work was
supported in part by the National Science and Engineering Research Council (NSERC) Scholarship of Government of Canada.