materials for femtospin project colin forbes [email protected]
TRANSCRIPT
![Page 2: Materials for Femtospin Project Colin Forbes cforbes628@qub.ac.uk](https://reader034.vdocuments.mx/reader034/viewer/2022050802/56649da05503460f94a8b309/html5/thumbnails/2.jpg)
Introduction
• Brief Overview of Key materials
• Material sequencing
• Overview of experimental results
• Future
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Materials of interest
• GdFeCo ternary alloys with 20-25% Gd & Co = 10%
• Gd/(FeCo) multilayers– 20-25% volume fraction of Gd
• FePt(5nm)/Co(5,10-20nm) bilayers
• FeRh
• FeTb – TbFe2 and TbFe3 ordered phases
• Elemental RE– GdFe2 ordered phases
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Material Sequencing
1. GdFeCo ternary alloy
2. Gd/(FeCo) multilayers
3. FePt(5nm)/Co(5,10-20nm) bilayers
4.= FeTb, FeTb2, FeTb3
4.= FeRh4.= Gd & GdFe2
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Experimental Analysis
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• Ternary Alloy Depositions– GdFeCo
• Gd – 15 - 30%• Fe – 60 – 75% 50nm• Co – 10%
• SiO2 wafers used as substrates
• Depositions done at ambient temperatures
• Samples sent to Seagate
Ternary Alloy Samples
SiO2
Ta
GdxFe90-xCo10
Ta 5nm
50nm
5nm
Where x = 15 - 30
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XRD Analysis Gd20Fe70Co10 (50nm)
• No crystalline structure• Amorphous surface
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Heated VSM GdFeCo alloys
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Heated VSM
• 20% Gd has perpendicular anisotropy at room temperature while 25% Gd has in plane anisotropy
• Magnetic properties change with temperature• 25% Gd switches from in plane to perpendicular anisotropy at
≈300°C
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• Multilayers of Gd and Fe90Co10 - (40nm)
• Volume factor of Gd was either 20 or 25%• Single bilayer• Double bilayer• Quadruple bilayer
• Depositions at room temperature
• Samples sent to Seagate
Gd/(FeCo) Multilayer Samples
SiO2
Ta
Gd
Fe90Co10
Ta
SiO2
Ta
Gd
Fe90Co10
Ta
Gd
Fe90Co10
SiO2
Ta
Gd
Fe90Co10
Ta
Gd
Fe90Co10
Gd
Fe90Co10
5nm
40nm
5nm
Gd
Fe90Co10
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BH Looper AnalysisTa(5nm)/[Gd(20%)/Fe90Co10](40nm)/Ta(5nm) in
Plane
Ta(5nm)/[Gd(25%)/Fe90Co10](40nm)/Ta(5nm) in Plane
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VSM Analysis of Gd/FeCo multilayers
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Ta(5nm)/[Gd(4nm)FeCo(16nm)]2(40nm)/Ta(5nm) in Plane
Temp / °C Temp / °C
Temp / °C
Temp / °C
Heated VSM Measurements
Ta(5nm)/[Gd(5nm)FeCo(15nm)]2(40nm)/Ta(5nm) in Plane
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• Decrease in both saturation & coercivity general trend• Not what was expected – in plane to perpendicular
anisotropy switching expected at compositional temp
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Future
• Improve multilayer structures of Gd/(FeCo)– Vary Volume fraction– Magnetic Properties– Crystal structure– Temperature analysis
• Investigate FePt/Co – FePt(5nm)Co(5,10-20nm) bilayers
• FeRh
• FeTb, FeTb2, FeTb3
• Gd & GdFe2