Master Project Midway progress report Quantifying the strength

Master Project Midway progress report Quantifying the strength of the magnetization pinning by Fe. Mn on Permalloy (Ni 80 Fe 20) thin films Steven Verstoep – 7 th of May 2008 1/13

Background Spin switch transistor GOAL: Find out if spin state pinning really works. 2/13

Outline Background (Just did that) Measurement Techniques – MFM Current Results Outlook – Anisotropic Magneto Resistance Theory Current Results Outlook Sample Holders Questions 3/13

MFM: Current Results 1/3 Magnetic Field by Single Dipole of Sample Simulation of MFM Force on Cantilever in Y-Direction Phase of Cantilever @ Resonance Phase of Cantilever @ -100 Hz 4/13

MFM: Current Results 2/3 Floppy 1. 3 bit/(100 um)2 sv 080227 floppy. 003 155 x 155 um Hard Disk 4. 4 bit/(um)2 sv 080227 hd. 006 5 x 5 um Height Range: 400 nm Height Range: 10 nm Phase Range: 6* Phase Range: 5* Scan height 40 nm 5/13

MFM: Current Results 3/3 3 D Height Range: 800 nm 2 D 50 nm Permalloy structures 2, 4, 6 um width sv 080311 py 50 nm_struc tures. 001 & sv 080311 py 50 nm_struc tures. 002 Phase Range: 3* Scan height: 100 nm 6/13

MFM: Outlook 1/2 Observe Magnetic Domains on Pinned Permalloy. Samples Py(6)Fe. Mn(10) Prepared: – Strips 4 x 40 um – Strips 2 x 40 um – Strips 1 x 40 um Do MFM in Leiden – Resurrect Scanner: As a “J-Scanner” (150 x 150 um) Preferred Or as an “E-Scanner” (15 x 15 um) Remove magnetic Holder – Use Helmholtz Coils Do MFM in Leuven – Use Helmholtz Coils – @ 10 K 7/13

MFM: Outlook 2/2 Are “Oortjes” real? – Examine in Electron Microscope 8/13

AMR: Theory Peaks at Magnetization switching. Gerard Verbiest: “Calculation of stray fields from small Permalloy strips and their effect in Permalloy / Nb bilayers. ” Wikipedia: The effect is attributed to a larger probability of s-d scattering of electrons in the direction of magnetic field. The net effect is that the electrical resistance has maximum value when the direction of current is parallel to the applied magnetic field. where μ = carrier mobility. Solving for the velocity, we find: http: //en. wikipedia. org//wiki/Magnet oresistance 9/13

AMR: Current Results 1/1 4 -Point Measurement on Unstructured 5 x 10 mm Sample B parallel to I Py(6)Fe. Mn(~30) 10 K P 1: H = 200 Oe P 2: H = 568 Oe Bias = 384 Oe Coercive Field = 184 Oe 10/13

AMR: Outlook 1/1 AMR on structured Sample Py(6)Fe. Mn(~30) Measure Magnetization: Structured & Unstructured 11/13

Sample Holder Molybdeen Idiot proof Suitable for: – – – Aceton Chemical cleaning Plasmalab Ion Beam (Maybe) Microscope Disadvantages: – Scratches – Contamination (Sputter, Resist) 12/13

Summary Goal: is spin pinning absolute Measure by – Observing domains in strips by MFM – Measuring Magneto resistance – Measuring Magnetization Sample: Py(6)Fe. Mn(10) Questions? 13/13