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Observations of Domain Motion in Magnetostrictive Materials Under Stress

Study on domain motion in magnetostrictive materials under various conditions like stress and field application. Analysis of changes in magnetization based on external forces. Findings on reversibility of magnetization changes.

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Observations of Domain Motion in Magnetostrictive Materials Under Stress

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  1. Magnetic Materials Group MOIF Observations of Domain Motion In Magnetostrictive Materials Under Stress Robert D. Shull & Alexander J. Shapiro National Institute of Standards and Technology Gaithersburg, Maryland Eckhard Quandt Center for Advanced European Studies and Research Ludwig-Erhard Allee 2, 53175 Bonn, Germany Manfred Wuttig Deptartment of Materials and Engineering University of Maryland, College Park, MD 20742

  2. Magnetic Materials Group (I). The Sample (II). How to Measure? (III). M Reversal in H┴ Deposited Films – via H┴ (IV). M Reversal in H45 Deposited Films – via H┴ (IV). M Reversal in H45 Deposited Films – via σ (IV). M Reversal in H┴ Annealed Films – via H┴ (IV). M Reversal in H┴ Annealed Films – via σ (V). M Reversal in H┴ Annealed Films – via H// (V). Summary OUTLINE

  3. Magnetic Materials Group SAMPLE } FeCo (9nm) 64 Repeats TbFe (7nm) BCC Si (300μm) Amorphous F F H┴ H//

  4. Magnetic Materials Group Teec-40 Thin Film 0.006 RT 0.004 0.006 0.002 0.004 0.002 Moment (kA.m2) 0 0 -0.002 -0.002 -0.004 -0.006 -0.004 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 moH(mT) -0.006 -6 -4 -2 0 2 4 6 moH(T)

  5. Magnetic Materials Group

  6. Magnetic Materials Group Stress Jig Light Beam Indicator Film FeCo (9 nm) TbFe (7 nm) Si (300 μm) MOIF Microscope Sample Domain Observation of TbFe/FeCo Under Stress and Field

  7. Magnetic Materials Group H┴ (100 Oe) - Deposited Film As Deposited After H┴= 0 H// = 132 Oe H┴ = -55 Oe ◘ H┴ Application: Vertical Walls form & move ◘H// Application: Walls fixed; M rotates

  8. Magnetic Materials Group H45° (100 Oe) - Deposited Film After H┴= 0 H// = 50 Oe H┴ = 50 Oe ◘ H┴ Application: Diagonal Walls form & move ◘H// Application: Walls move; M rotates

  9. Magnetic Materials Group ◘ σ Application: Diagonal Walls are fixed; M rotates to // ◘σ Removal: Walls still fixed; M rotates back H45° (100 Oe) - Deposited Film σ= 3 σ= 10 As Prepared H┴ = 50 Oe σ= 4 σ= 2 σ= 0

  10. Magnetic Materials Group H┴ (50 Oe) - Annealed Film H┴= -16 Oe H┴= -20 Oe H┴= -90 Oe H┴= 0 H┴= +19 Oe H┴= 0 ◘ H┴ Application: Walls move to form Single Domain ◘H┴ Reversal: Few Vertical Walls form & move

  11. Magnetic Materials Group As Prepared σ= 3 ◘ σ Application: Vertical Walls are fixed; M rotates to // ◘σ Removal: Walls still fixed; M rotates back σ= 6 σ= 1 H┴ (50 Oe) - Annealed Film

  12. Magnetic Materials Group H┴ (50 Oe) - Annealed Film H// = 0.5 Oe H// = 27 Oe H// = 40 Oe H// = 0 ◘ H// Application: Walls disappear; M rotates to Single Domain ◘H// Removal: Single Domain remains; slight M rotation

  13. Magnetic Materials Group SUMMARY Changes in the magnetization of multilayered magnetostrictive films depend on the INITIAL state & on the NATURE of the external force As expected for Positive magnetostriction, M aligns along the axis of stress just as M aligns along H when a magnetic field is applied End states are Different for σ & H// application! M is non-uniform during stress application, even at large stresses; M becomes uniform for large applied fields Changes in M are REVERSIBLE for stress application; Changes in M are NOT Reversible for field application

  14. Magnetic Materials Group

  15. Magnetic Materials Group H┴ (100 Oe) - Deposited Film As Deposited After H┴= 0 H// = 132 Oe H┴ = -55 Oe

  16. Magnetic Materials Group H45° (100 Oe) - Deposited Film After H┴= 0 H// = 50 Oe H┴ = 50 Oe

  17. Magnetic Materials Group H45° (100 Oe) - Deposited Film σ= 3 σ= 10 As Prepared After H┴= 0 H// = 50 Oe H┴ = 50 Oe σ= 4 σ= 2 σ= 0

  18. Magnetic Materials Group H┴ (50 Oe) - Annealed Film H┴= -16 Oe H┴= -20 Oe H┴= -90 Oe H┴= 0 H┴= +19 Oe H┴= 0

  19. Magnetic Materials Group H┴ (50 Oe) - Annealed Film As Prepared σ= 3 σ= 6 σ= 1

  20. Magnetic Materials Group H┴ (50 Oe) - Annealed Film H// = 0.5 Oe H// = 27 Oe H// = 40 Oe H// = 0

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