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Investigation of Cu80(Sm0.17Co0.83)10Fe10 ribbons
with magnetoresistive properties
R. Lardé
J.M. Le Breton, F. Richomme, A. Hauet, O. Crisan, J. Teillet
GPM UMR CNRS 6634 Université de ROUEN, France
A. Maignan
CRISMAT UMR CNRS 6508 ISMRA CAEN, France
PLAN OF THE TALK
I – Introduction
- Aims of the study
- Samples preparation
II – Structural investigation of Cu80(Sm0.17Co0.83)10Fe10
- X-ray diffraction analyses
- Mössbauer analyses
III – Magnetic and transport properties
IV – Conclusion
I- INTRODUCTION
INTRODUCTION
- Aims of the study
- Samples preparation
I- INTRODUCTION
Aims of the study
Elaboration of granular alloys Cu80(Sm0.17Co0.83)10Fe10
consisting in magnetic clusters (SmCo5 , -Fe) embedded in a Cu matrix
Cu
SmCo5
-Fe
Investigation of the structural, magnetic and magnetoresistive properties
- X-ray diffraction
- Mössbauer spectrometry
- T.E.M analyses
- magnetization and resistivity measurements
Fundamental study of effect of adding SmCo5 phase on the magnetoresistance
I- INTRODUCTION
Samples preparation
Melt spinning method
- Cu roller (= 400 mm, Vmax=60 m/s)
- Initial constituents : pure Cu, Fe and SmCo5
- Obtained ribbons : thickness of 15-20 m
width of 2-3mm
Annealing treatments
- Performed in a resistive furnace under vacuum
- Annealing at 400, 450, 520 and 650°C for 1h
ribbon
Copper wheel
II- STRUCTURAL INVESTIGATION
STRUCTURAL
INVESTIGATION
II- STRUCTURAL INVESTIGATION
Cu -Fe
X-ray diffraction
Cu
Cu
Cu80(Sm0.17Co0.83)10Fe10
Cu
-Fe
Cu
-Fe
Tan=650°C
Sm2O3
Tan=520°C
Tan=450°C
Tan=400°C
As-cast
15
20
25
30
After quenching
35
 (°)
40
45
50
55
60
3 crystalline phases: fcc-Cu, bcc-Fe and hcp-SmCo5
Phase separation during quenching
Upon annealing
Structural refinement up to 450°C
Oxidation of SmCo5 phase above 520°C
SmCo5
II- STRUCTURAL INVESTIGATION
Transmission Electron Microscopy
Cu80(Sm0.17Co0.83)10Fe10
After annealing at 450°C
Nanometric precipitates
dispersed in Cu matrix
Size of the precipitates: <10 nm
50 nm
Mössbauer analyses
II- STRUCTURAL INVESTIGATION
V e l o c i t y
- 1 0
0
(
m
m
/
s
)
Cu80(Sm0.17Co0.83)10Fe10
+ 1 0
After quenching
1 . 0 0
88% magnetic Fe with Bhf >33T
As-quenched
formation of -Fe(Co)
0 . 9 9
1 . 0 0
Bhf= 34.9 T
12% of paramagnetic Fe
Fe atoms dispersed in Cu
Tan= 400°C
0 . 9 9
1 . 0 0
Bhf= 35 T
Tan= 450°C
Upon annealing up to 450°C
The -Fe(Co) line width decreases
Ab s o r p t i o n
0 . 9 8
1 . 0 0
Bhf= 35 T
The paramagnetic component decreases
structural refinement
Tan= 520°C
(
0 . 9 9
1 . 0 0
Bhf= 35.5 T
Upon annealing up to 650°C
%
Bhf of -Fe(Co) increases up to 36 T
)
Tan= 650°C
0 . 9 8
Bhf= 36 T
oxidation of SmCo5
III- MAGNETIC AND TRANSPORT PROPERTIES
MAGNETIC
AND
TRANSPORT PROPERTIES
III- MAGNETIC AND TRANSPORT PROPERTIES
ZFC curve (increasing temperature)
Progressive deblocking of SPM particles
0.15
H=30Oe
0.14
0.13
-Fe(Co) at low T ; SmCo5 at high T
As-quenched
0.12
Tcri
0.11
0.10
FC curve (decreasing temperature)
0.09
Blocking of SPM -Fe(Co) below Tcri due to magnetic interactions
between SmCo5 and -Fe(Co) particles
0.08
0.07
-
50
100
150
200
250
300
T(°K)
0.2
0.19
H=30Oe
0.18
Tan= 400°C
M (emu/g)
0.17
0.16
Cu80(Sm0.17Co0.83)10Fe10
Tcri
0.15
0.14
0.13
0.12
0.11
0.1
0
50
100
150
200
250
300
Increase of magnetization
T (°K)
0.25
H=30Oe
0.23
0.21
Formation of SPM particles from diluted magnetic atoms
Tcri
0.19
M (emu/g)
M (emu/g)
ZFC/FC magnetization curves
Tan= 450°C
Increase of the particle size
0.17
0.15
0.13
0.11
0.09
0.07
0
50
100
150
T (°K)
200
250
300
M(H) magnetization curves
III- MAGNETIC AND TRANSPORT PROPERTIES
Cu80(Sm0.17Co0.83)10Fe10
40.00
30.00
20.00
As-quenched
Tan= 450°C
10.00
-5.E+04 -4.E+04
-3.E+04 -2.E+04
-1.E+04
0.E+00
1.E+04
-10.00
2.E+04
H (Oe)
3.E+04
4.E+04
5.E+04
-20.00
-30.00
300 K
-40.00
After quenching
Rapid saturation of 98% of total magnetization at 1 T
FM contribution
Low H ( 100-200 Oe)
c
After annealing at 450°c
Increase of Ms (Ms = M(H=5T))
Saturation of 95% of total magnetization at 1 T followed by a small slope in high field
FM + SPM contribution
III- MAGNETIC AND TRANSPORT PROPERTIES
Resistivity Vs Temperature curves
Cu80(Sm0.17Co0.83)10Fe10
0.03
Brut
As-quenched
Résistance (ohm)
0.025
0.02
Resistivity drop
0.015
1h 400°c
0.01
1h 450°c
0.005
1h 520°c
0
0
50
100
150
200
250
300
T (K)
Upon annealing
Elimination of defects, strain relaxation
Purification of the Cu matrix
decrease of the spin independent contribution to the resistivity
III- MAGNETIC AND TRANSPORT PROPERTIES
MR curves at 5K
Cu80(Sm0.17Co0.83)10Fe10
After quenching
H (Oe)
-50000
-30000
-10000
10000
30000
50000
70000
0
As-quenched
As-cast
-2
-4
-10
No saturation observed
Upon annealing
-6
-8
Linear decrease of MR with H
520°C
Initial steep decrease in MR
MR (%)
-70000
Rapid rotation of the magnetization
of the magnetic clusters
450°C
-12
-14
400°C
Long MR tail
Paramagnetic or superparamagnetic
fluctuations
-16
MR 
( R( H )  R(0))
*100
R(0)
Mrmax =16% at 7T (Tan= 400°C)
Optimum annealing conditions
IV- CONCLUSION
CONCLUSION
IV- CONCLUSION
Structural characterization
Melt spinning
- Nanostructured granular alloys
-Fe(Co) and SmCo5 magnetic clusters dispersed in Cu matrix
Annealing treatment
- Structural refinement
- Oxidation of SmCo5 at annealed temperature higher than 450°C
Magnetoresistive behaviour
Cu80(Sm0.17Co0.83)10Fe10 ribbons
Significant MR observed in the presence of hard magnetic phase
Existence of optimum annealing temperature
The contribution to the MR of magnetic clusters formed during quenching seems weak
contrary to that formed after annealing
The end
III- MAGNETIC AND TRANSPORT PROPERTIES
MR curves at 300K
Cu80(Sm0.17Co0.83)10Fe10
-70000
-50000
-30000
-10000
H (Oe)
10000
30000
50000
0
-0.2
Tan= 450°C
-0.4
-0.8
-1
MRG (%)
-0.6
-1.2
-1.4
-1.6
-1.8
-2
At 300K the magnetoresistance amplitude is reduce
70000