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The A1 to L1 0 Transformation in FePt Films with Ternary Alloying Additions: The Heats of Formation of Fe3Pt, FePt and FePt 3 Katayun Barmak, Carnegie-Mellon University , DMR 0804765.
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The A1 to L10 Transformation in FePt Films with Ternary Alloying Additions: The Heats of Formation of Fe3Pt, FePt and FePt3Katayun Barmak, Carnegie-Mellon University, DMR 0804765 L10 ordered FePt is currently the leading candidate material for ultrahigh density heat assisted magnetic recording (HAMR) and bit patterned magnetic recording (BPMR) media. Measurements of the heats of formation of phases in the Fe-Pt system and the sequence of formation of phases in multilayer films is of importance to alloy and process design for the production of these recording media. The measured values were found to agree within 10% with one of two sets of reported first principles calculated values. Independent of the overall film composition the reaction path included the formation of all the solid phases from the binary phase diagram, namely L12 Fe3Pt, L10 FePt, L12 FePt3 and the solid solution (Fe,Pt) also termed A1 FePt. In addition L12 Fe3Pt, metastable DO22 Fe3Pt was seen to form in the most Fe-rich multilayer. B. Wang, D. C. Berry, Y. Chiari, and K. Barmak, J. Appl. Phys. 109, 013903:1-8
Images taken from MRS Bulletin, 31 (2006). The A1 to L10 Transformation in FePt Films with Ternary Alloying Additions: The Heats of Formation of Fe3Pt, FePt and FePt3 Katayun Barmak, Carnegie-Mellon University, DMR 0804765 • Further increases in areal storage density of magnetic recording media require new alloys that have large magnetocrystalline anisotropy energy densities and thus allow smaller grains with thermally stable moments to be achieved – L10 ordered FePt is one such alloy • One of the coauthors on the recently published paper on this work, Ysela Chiari, was an undergraduate student who participated in an NSF-funded summer REU program. She carried out a number of the differential scanning calorimetry runs for the measurement of the heats of formation of the Fe-Pt compounds. K. Barmak Hard Disk Drive B. Wang, D. C. Berry, Y. Chiari, and K. Barmak, J. Appl. Phys. 109, 013903:1-8