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Investigation of Cu 80 (Sm 0.17 Co 0.83 ) 10 Fe 10 ribbons with magnetoresistive properties

Investigation of Cu 80 (Sm 0.17 Co 0.83 ) 10 Fe 10 ribbons with magnetoresistive properties. R. Lardé J.M. Le Breton, F. Richomme, A. Hauet, O. Crisan, J. Teillet GPM UMR CNRS 6634 Université de ROUEN, France A. Maignan CRISMAT UMR CNRS 6508 ISMRA CAEN, France. PLAN OF THE TALK.

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Investigation of Cu 80 (Sm 0.17 Co 0.83 ) 10 Fe 10 ribbons with magnetoresistive properties

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  1. Investigation of Cu80(Sm0.17Co0.83)10Fe10 ribbons with magnetoresistive properties R. Lardé J.M. Le Breton, F. Richomme, A. Hauet, O. Crisan, J. Teillet GPM UMR CNRS 6634 Université de ROUEN, France A. Maignan CRISMAT UMR CNRS 6508 ISMRA CAEN, France

  2. PLAN OF THE TALK I – Introduction - Aims of the study - Samples preparation II – Structural investigation of Cu80(Sm0.17Co0.83)10Fe10 - X-ray diffraction analyses - Mössbauer analyses III – Magnetic and transport properties IV – Conclusion

  3. I- INTRODUCTION INTRODUCTION - Aims of the study - Samples preparation

  4. Aims of the study I- INTRODUCTION Elaboration of granular alloys Cu80(Sm0.17Co0.83)10Fe10 consisting in magnetic clusters (SmCo5 , -Fe) embedded in a Cu matrix Cu SmCo5 -Fe Investigation of the structural, magnetic and magnetoresistive properties - X-ray diffraction - Mössbauer spectrometry - T.E.M analyses - magnetization and resistivity measurements Fundamental study of effect of adding SmCo5 phase on the magnetoresistance

  5. Samples preparation ribbon Copper wheel I- INTRODUCTION Melt spinning method - Cu roller (= 400 mm, Vmax=60 m/s) - Initial constituents : pure Cu, Fe and SmCo5 - Obtained ribbons : thickness of 15-20 m width of 2-3mm Annealing treatments - Performed in a resistive furnace under vacuum - Annealing at 400, 450, 520 and 650°C for 1h

  6. II- STRUCTURAL INVESTIGATION STRUCTURAL INVESTIGATION

  7. X-ray diffraction After quenching 3 crystalline phases: fcc-Cu, bcc-Fe and hcp-SmCo5 Phase separation during quenching Upon annealing Structural refinement up to 450°C Oxidation of SmCo5 phase above 520°C II- STRUCTURAL INVESTIGATION Cu80(Sm0.17Co0.83)10Fe10 Sm2O3 SmCo5

  8. Transmission Electron Microscopy 50 nm II- STRUCTURAL INVESTIGATION Cu80(Sm0.17Co0.83)10Fe10 After annealing at 450°C Nanometric precipitates dispersed in Cu matrix Size of the precipitates: <10 nm

  9. Mössbauer analyses Bhf= 35.5 T Bhf= 35 T Bhf= 35 T Bhf= 34.9 T Upon annealing up to 450°C The -Fe(Co) line width decreases The paramagnetic component decreases structural refinement Upon annealing up to 650°C Bhf of -Fe(Co) increases up to 36 T oxidation of SmCo5 Bhf= 36 T II- STRUCTURAL INVESTIGATION Cu80(Sm0.17Co0.83)10Fe10 After quenching 88% magnetic Fe with Bhf >33T As-quenched formation of -Fe(Co) 12% of paramagnetic Fe Fe atoms dispersed in Cu Tan= 400°C Tan= 450°C Tan= 520°C Tan= 650°C

  10. III- MAGNETIC AND TRANSPORT PROPERTIES MAGNETIC AND TRANSPORT PROPERTIES

  11. ZFC/FC magnetization curves III- MAGNETIC AND TRANSPORT PROPERTIES ZFC curve (increasing temperature) H=30Oe Progressive deblocking of SPM particles -Fe(Co) at low T ; SmCo5 at high T As-quenched Tcri FC curve (decreasing temperature) Blocking of SPM -Fe(Co) below Tcri due to magnetic interactions between SmCo5 and -Fe(Co) particles H=30Oe Tan= 400°C Cu80(Sm0.17Co0.83)10Fe10 Tcri Increase of magnetization H=30Oe Formation of SPM particles from diluted magnetic atoms Tcri Tan= 450°C Increase of the particle size

  12. M(H) magnetization curves As-quenched Tan= 450°C After quenching Rapid saturation of 98% of total magnetization at 1 T Low Hc ( 100-200 Oe) III- MAGNETIC AND TRANSPORT PROPERTIES Cu80(Sm0.17Co0.83)10Fe10 M(emu/g) H (Oe) 300 K FM contribution After annealing at 450°c Increase of Ms (Ms = M(H=5T)) Saturation of 95% of total magnetization at 1 T followed by a small slope in high field FM + SPM contribution

  13. Resistivity Vs Temperature curves As-quenched Resistivity drop Resistivity () III- MAGNETIC AND TRANSPORT PROPERTIES Cu80(Sm0.17Co0.83)10Fe10 Upon annealing Elimination of defects, strain relaxation Purification of the Cu matrix decrease of the spin independent contribution to the resistivity

  14. MR curves at 5K III- MAGNETIC AND TRANSPORT PROPERTIES Cu80(Sm0.17Co0.83)10Fe10 After quenching Linear decrease of MR with H No saturation observed As-quenched Upon annealing Initial steep decrease in MR Rapid rotation of the magnetization of the magnetic clusters Long MR tail Paramagnetic or superparamagnetic fluctuations Mrmax =16% at 7T (Tan= 400°C) Optimum annealing conditions

  15. IV- CONCLUSION CONCLUSION

  16. Structural characterization Melt spinning - Nanostructured granular alloys -Fe(Co) and SmCo5 magnetic clusters dispersed in Cu matrix Annealing treatment - Structural refinement - Oxidation of SmCo5 at annealed temperature higher than 450°C IV- CONCLUSION Magnetoresistive behaviour Cu80(Sm0.17Co0.83)10Fe10 ribbons Significant MR observed in the presence of hard magnetic phase Existence of optimum annealing temperature The contribution to the MR of magnetic clusters formed during quenching seems weak contrary to that formed after annealing

  17. The end

  18. MR curves at 300K III- MAGNETIC AND TRANSPORT PROPERTIES Cu80(Sm0.17Co0.83)10Fe10 Tan= 450°C At 300K the magnetoresistance amplitude is reduce

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