Materials for Femtospin Project Colin Forbes [email protected].
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Transcript of Materials for Femtospin Project Colin Forbes [email protected].
Introduction
• Brief Overview of Key materials
• Material sequencing
• Overview of experimental results
• Future
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
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
Experimental Analysis
• 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
XRD Analysis Gd20Fe70Co10 (50nm)
• No crystalline structure• Amorphous surface
Heated VSM GdFeCo alloys
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
• 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
BH Looper AnalysisTa(5nm)/[Gd(20%)/Fe90Co10](40nm)/Ta(5nm) in
Plane
Ta(5nm)/[Gd(25%)/Fe90Co10](40nm)/Ta(5nm) in Plane
VSM Analysis of Gd/FeCo multilayers
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
• Decrease in both saturation & coercivity general trend• Not what was expected – in plane to perpendicular
anisotropy switching expected at compositional temp
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
