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Large and Local Magnetoresistance in a State-of-the-Art Perpendicular Magnetic Medium
Morgan Williamson1,2, Cheng Wang3, Pin-Wei Huang3
1Physics Department, University of Texas at Austin, Austin, TX 78712, USA.
Nanotechnology, Science and Applications
|January 20, 2021
Summary
Researchers studied magnetotransport in CoPtCr films, finding negligible bulk magnetoresistance but over 10,000% giant-magnetoresistance-like effects at the nanoscale. This suggests potential for novel high-density magnetic recording applications.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Granular oxide-segregated CoPtCr films are crucial for high-density magnetic recording in hard disk drives.
- Understanding magnetotransport properties at different length scales is key to advancing magnetic storage technology.
Purpose of the Study:
- To investigate the magnetotransport properties of granular oxide-segregated CoPtCr films on both macroscopic and microscopic scales.
- To explore the potential of these films for novel magnetic recording concepts with high areal density.
Main Methods:
- Utilized epitaxy-like sputtering to deposit CoPtCr films with multiple perpendicularly magnetized granular layers.
- Performed bulk magnetoresistance measurements using the Van der Pauw geometry.
- Conducted local transport analysis via point-contact magnetoresistance measurements.
Main Results:
- Bulk film measurements exhibited negligible magnetoresistance (<0.02%).
- Point-contact measurements revealed significant giant-magnetoresistance-like changes exceeding 10,000% (ΔR/R).
Conclusions:
- The large local magnetoresistance is attributed to tunnel magnetoresistance between CoPtCr grains with varying coercivities.
- Tunneling transport was confirmed by observed current-voltage characteristics and bias-dependent magnetoresistance, with both decreasing under applied DC bias.
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