magnetic pinning geometry for sensing with magnetic domain walls

Magnetic pinning geometry for sensing with magnetic domains walls

Héctor Corte-León1, Vahid Nabaei2,3, Alessandra Manzin2, Jon Fletcher1, Patryck Kryzstecko4, Hans Schumacher4, and Olga Kazakova1

1National Physical Laboratory, Hampton Road, Teddington, TW11 0LW, UK.2Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, I-10135, Italy3Dipartimento Energia, Politecnico di Torino, Torino, I-10129, Italy4Physikalisch-Technische Bundesanstalt, Braunschweig, D-38116, Germany

Project motivation and objectives Design and fabrication Identification of stable states Electrical transport

State space Conclusion

Project motivation and objectives Design and fabrication Identification of stable states Electrical transport

State space Conclusion

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Project motivation and objectives

DW electronics

Magnetization carries the information.

Practically no heating.

Very stable states.

Simpler designs

D.A. Allwood, G. Xiong, C. C. Faulkner, D. Atkinson, D. Petit, R. P. Cowburn, Science 309, 1688 (2005)

L. Thomas, S-H. Yang, K-S. Ryu, B. hughes, C. Rettner, D-S. Wang, C-H Tsai, K-H. Shen, S. Parkin, IEDM, 24.2 (2011)

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Project motivation and objectives

P. Vavassori, Donolato et al, Appl. Phys. Lett. 93, 203502 (2008)

Biosensors and manipulators

Nanobead transport and detection.

Cell manipulation.

Standarization needed.

E. Rapoport, Appl. Phys. Lett. 100, 082401 (2012)

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Proposed structure for nanobead detection

Domain Walls attract nanobeads.

Nanobead modifies local magnetic field.

Resistance is affected by Domain Wall through Anisotropic Magnetoresistance effect.

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Project motivation and objectives

Donolato et al, Nanotechnology 20 385501 (2009)

Project motivation and objectives Design and fabrication Identification of stable states Electrical transport

State space Conclusion

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Design and fabrication

L-shape nanostructure of Py (Ni20Fe80)

Si/SiO2 substrate

Pt protective layer on top of Py

Gold contacts

Project motivation and objectives. Design and fabrication. Identification of stable states. Electrical transport.

State space. Conclusion.

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Identification of stable states

Using a Magnetic Force Microscope and an electromagnetic coil we are able to trap and remove DW in the corner of the device.

Magnetic Field

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Identification of stable states 4 States were identified at zero field.

Project motivation and objectives Design and fabrication Identification of stable states Electrical transport

State space Conclusion

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Transport measurements

Anisotropic magnetoresistance.Resistance of a material depends on the interaction between

magnetization and electrical current.

R=R┴+∆Rcos2

Magnetic Material

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Transport measurements

Setup.AC current,10A.

Voltage across corner.

Measure ∆R

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Magnetic Field

Transport measurements

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B(mt)

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State space

4 stable states identified at zero field.

Device is set into one of these 4 states.

Starting with a well defined state, measure the evolution of the device when applying magnetic field in different directions.

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State space

[1,1] [-1,-1]

[-1,1] [1,-1]

[1,1][-1,-1]

[1,-1][-1,1]

[-1,1]

[-1,-1]

[1,-1][-1,1]

[1,-1]

[1,1]

[1,-1]

[-1,-1]

[-1,1]

[1,1][1,1]

[-1,1][1,-1]

[-1,-1]

57.6

57.1

57.35

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State space

1

2

23 3

4

5 ≡1

12 3

4 5≡1Res

ista

nce

()

Time (a.u.)

4

57.6

57.1

57.35

Extracted

Measured

Project motivation and objectives Design and fabrication Identification of stable states Electrical transport

State space Conclusion

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Conclusion

Domain wall pining geometry has been tested with AMR.

Stable states have been identified. Low/high resistance states correspond to

presence/absence of the domain wall. Complete state space map has been measured. Noise analysis is used for determination of the best

working parameters.

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Future experiments:Bead Detection

Focus Ion Beam and micromanipulators.

Beads placed manually one by one.

Superparamagnetic Dynal® beads.

Magnetic Nanobead experiments will quantify the sensing properties of the structure.

Thanks to everyone.