Film e multistrati magnetici

INFM-L’AQUILA
FILM E MULTISTRATI MAGNETICI
Franco Lucari
4/4
UNIVERSITÀ DELL’AQUILA
• Film e multistrati magnetici
Università dell’Aquila - FIRB
Il gruppo è composto
da:
• Lucari Franco
• D’Orazio Franco
• Continenza
Alessandra
Utilizza alcuni borsisti
oltre a due tecnici:
• Giammaria Franco
• Rossi Lorella
Tematiche di interesse:
N. 1 e N. 4
Work packages:
WP1, WP3 e WP4
Le apparecchiature in dotazione
• Apparato di misura magneto-ottico per misure Faraday,
Kerr polare o longitudinale, MCD, MLD: campo
magnetico B≤5600 gauss, temperatura 4 ≤T≤300 K,
lunghezza d'onda 0.4≤l≤2.6 mm.
• Suscettometro Lakeshore 7030: frequenza 5≤n≤10000
Hz, temperatura 15 ≤T≤300 K, campo magnetico di
misura 0.1≤H≤25 Oe.
• Apparato di deposizione per sputtering (magnetron, 3
catodi)
• Magnetometro AGFM Princeton Instr., Campo B < 1.4 T
• Calcolatori
Apparecchiature a cui è possibile
accedere localmente
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•
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Diffrazione a raggi X
SEM (TEM?)
XPS
Microscopia a forza atomica
Microscopia a forza magnetica (?)
Apparecchiature da allestire in
parte finanziate da FIRB:
• Sistema d'immagine magnetica Kerr
• Apparecchiatura magneto-ottica in
situ sull'apparato di sputtering
• Criostato per Magnetometro AGFM
Materiali studiati
• Film e multistrati di:
Fe-Al, Co-Fe, Co-CoO, Ni-NiO
• Ge(Mn)
• CoPt
Magneto-Optical Kerr Effect
(MOKE) measurements
variable wavelength,
variable temperature,
Hysteresis loops
EXCHANGE-BIAS
COUPLING IN Co/CoO
BILAYERS
sample # substrate O2 Flux
(sccm)
1
glass
1
2
glass
2
3
glass
4
Si[100]
1
d-Co
(nm)
14.2
15.3
28.0
13.1
d-CoO
(nm)
4.5
4.0
4.9
Sample #3
q (°)
0.04
0.02
H (kOe)
0.00
200 K
-0.02
50 K ZFC
50 K FC
-0.04
-6
-4
-2
0
2
4
6
HEB (kOe)
1.5
1.0
Exchange-Bias
Field vs.
Temperature
#1
#2
#3
#4
0.5
0.0
HC (kOe)
0
2
ZFC
100
T (K)
200
FC
Coercive Field vs.
Temperature
1
0
0
T (K)
300
[Fex/Aly]N multilayers on
Si(100)
q K (°)
0.05
0.00
-10
-5
0
5
H (Oe)
10
-0.05
Longitudinal MOKE hysteresis on sample
[Fe/Al] x 4. The film is oriented with the easy
magnetization axis parallel to the H direction
[Fex/Aly]4
MR/MS
1.0
0.5
0.0
-30 0
F (°)
30
60
90 120 150 180
Loop squareness vs. the angle between the [011]
axis of the substrate and the magnetic field
direction
[Fex/Aly]N
Hc(Oe)
10
8
6
4
2
0
1
2
3
4
5
N
6
7
Coercive field as a function of the number of Fe/Al
layer pairs
[CoFe]
24 Oe
25 Oe
26 Oe
27 Oe
28 Oe
29 Oe
30 Oe
40 Oe
50 Oe
-150200 Oe
0.015
KR (°)
0.01
0.005
H (Oe)
0
-50
-0.005
50
-0.01
-0.015
T = 30 K - Minor Loops
150
MnxGe1-x
q (°)
0.03
Mn 2.7%
Mn 4.4%
Mn 5.3%
0.02
0.01
0.00
H (kOe)
-0.01
MOKE hysteresis
loop at Tmeas = 100 K for the
samples deposited atG T=
160 °C.
-0.02
-0.03
-6
-4
-2
0
2
4
6
Coercive field vs. Temperature
4
HC (kOe)
Temperature
dependence of the
coercive field for the
samples deposited at
TG = 160 °C.
Mn 2.7%
2
Mn4.4%
Mn 5.3% (Hcx10)
Mn 2.7% after aging
0
0
100
T (K)
200
300
Magnetization vs. Temperature
0.8
Temperature
dependence of MOKE
saturation normalized to
Mn concentration for the
samples deposited at
TG = 160 °C.
S/x
(°)
0.6
Mn 2.7%
0.4
Mn4.4%
Mn 5.3%
Mn 2.7% after aging
0.2
0
0
100
T (K)
200
300
Misure di Magnetizzazione
(Alternating Field
Magnetometer)
Hysteresis
and
Switching Field
Distribution
CoPt
T = 600°C, p = 4.7  10-7 mbar
Isothermal Remanent Magnetization
and
Demagnetization Remanence Curves
CoPt
T = 600°C, p = 4.7  10-7 mbar
Magnetization Decay
CoPt
T = 600°C, p = 4.7  10-7 mbar
Multiple Segments, Minor Loops, etc.
CoPt
T = 500°C, p = 3.6  10-7 mbar