Probing Magnetic Configurations in Co/Cu Multilayered NanowiresJared Wong, Peter Greene, Randy Dumas, and Kai Liu

Department of Physics, University of California, Davis, California, 95616, USAApplied Physics Letters 94,032504 (2009)

Fabrication via Electrodepostion

TEMCourtesy of Daniel Masiel and Nigel D.

Browning, UC Davis

Magnetic Properties

Reversal Mechanisms in Fe Nanodisks

Magnetoresistance Properties

Summary

H

H

-4 -2 0 2 4

-1.0

-0.5

0.0

0.5

1.0

[Co(10nm)/Cu(250nm)]5

Perpendicular to wire Parallel to wire

M/M

S

H (kOe)

-4 -2 0 2 4

-1.0

-0.5

0.0

0.5

1.0

[Co(55nm)/Cu(350nm)]4

Perpendicular to wire Parallel to wire

M/M

S

H (kOe)

0

0.5

1

1.5

-0.9 -0.6 -0.3 0 0.3 0.6 0.9

10 nm32 nm37 nm39 nm41 nm55 nm

W(M

/Ms)

/ W(0

)

M / Ms

M/MS

H

R. K. Dumas, et al,

PRB 75, 134405 (2007); APL 91, 202501 (2007).

2 ( , )1( , )

2R

RR

M H HH H

H H

FORC distribution

2R

C

H HH

2R

B

H HH

Local Coercivity:

Bias Field:

50nm diameter [Co(5nm)/Cu(8nm)]400

H (Oe)

H wiresH // wires

-5.0 -2.5 0.0 2.5 5.0

4.56

4.57

(a) Field Parallel to Wire

R (

Oh

m)

H (kOe)

Decreasing field Increasing field

-5.0 -2.5 0.0 2.5 5.0

4.54

4.55

4.56

4.57

(b) Field Perpendicular to Wire

R (

Oh

m)

H (kOe)

Decreasing field Increasing field

2cos)( RRR T R RR

GMRAMR

AMR

200nm diameter [Co(50nm)/Cu(10nm)]150

200nm diameter wires

Superposition of AMR (vortex core) and GMR

0.1

0.2

0.3

0.4

0.5

Wire

// Wire

0 10 20 30 40 50 60

Coe

rciv

ity

(kO

e)

Co Thickness (nm)

0

10

20

30

40

0 10 20 30 40 50 60

Rem

anen

ce (

%)

Co Thickness (nm)

• Investigated magnetization reversal mechanisms in Co nanodisks embedded in multilayered nanowires by changing the Co aspect ratio.

•Captured magnetic and magnetoresistance "fingerprints" of single domain vs. vortex state reversal:in 200 nm nanowires, single domain for Co thickness < 32nm and vortex state for Co thickness > 37 nm.

K. Liu et al, PRB 51, 7381 (1995).

CITRIS, NSF (Grant Nos. ECCS-0725902 and PHY-0649297) and the Alfred P. Sloan Foundation

[Co(10nm)/Cu(250nm]5 [Co(55nm)/Cu(350nm]4