Size and shape effects on the order–disorder phase transition in CoPt nanoparticles
Source abstract
Abstract
Chemically ordered bimetallic nanoparticles are promising candidates for magnetic-storage applications. However, the use of sub-10 nm nanomagnets requires further study of possible size effects on their physical properties. Here, the effects of size and morphology on the order-disorder phase transition temperature of CoPt nanoparticles (T(C)(NP)) have been investigated experimentally, using transmission electron microscopy, and theoretically, with canonical Monte Carlo simulations. For 2.4-3-nm particles, T(C)(NP) is found to be 325-175 degrees C lower than the bulk material transition temperature, consistent with our Monte Carlo simulations. Furthermore, we establish that T(C)(NP) is also sensitive to the shape of the nanoparticles, because only one dimension of the particle (that is, in-plane size or thickness) smaller than 3 nm is sufficient to induce a considerable depression of T(C)(NP). This work emphasizes the necessity of taking into account the three-dimensional morphology of nano-objects to understand and control their structural properties.
Source: europepmc · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Magnetic properties of thin films · nanoparticles nucleation surface interactions · Theoretical and Computational Physics
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (35)
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1. Plumer, M. L., Van Ek, J. & Weller, D. The Physics of Ultra-High-Density Magnetic Recording (Springer, 2001).10.1007/978-3-642-56657-8 ↗
2. Sellmyer, D. J., Yu, M. & Kirby, R. D. Nanostructured magnetic films for extremely high density recording. Nanostruct. Mater. 12, 1021–1026 (1999).10.1016/S0965-9773(99)00291-3 ↗
3. Yu, M., Liu, Y. & Sellmyer, D. J. Nanostructure and magnetic properties of composite CoPt:C films for extremely high-density recording. J. Appl. Phys. 87, 6959–6961 (2000).10.1063/1.372899 ↗
4. Himpsel, F. J., Ortega, J. E., Mankey, G. J. & Willis, R. F. Magnetic nanostructures. Adv. Phys. 47, 511–597 (1998).10.1080/000187398243519 ↗
5. Weller, D. & Moser, A. Thermal effect limits in ultrahigh-density magnetic recording. IEEE Trans. Magn. 35, 4423–4439 (1999).10.1109/20.809134 ↗
6. Ariake, J., Chiba, T., Watanabe, S., Honda, N. & Ouchi, K. Magnetic and structural properties of Co–Pt perpendicular recording media with large magnetic anisotropy. J. Magn. Magn. Mater. 287, 229–233 (2005).10.1016/j.jmmm.2004.10.037 ↗
7. Klemmer, T., Hoydick, D., Okumura, H., Zhang, B. & Soffa, W. A. Magnetic hardening and coercivity mechanisms in L10 ordered FePd ferromagnets. Scr. Metallurg. Mater. 33, 1793–1805 (1995).10.1016/0956-716X(95)00413-P ↗
8. Sakuma, A. First principle calculation of the magnetocrystalline anisotropy energy of FePt and CoPt ordered alloys. J. Phys. Soc. Jpn 63, 3053–3058 (1994).10.1143/JPSJ.63.3053 ↗
9. Christodoulides, J. A. et al. CoPt and FePt thin films for high density recording media. J. Appl. Phys. 87, 6938–6940 (2000).10.1063/1.372892 ↗
10. Sato, K., Bian, B. & Hirotsu, Y. Fabrication of oriented L10–FePt and FePd nanoparticles with large coercivity. J. Appl. Phys. 91, 8516–8518 (2002).10.1063/1.1456446 ↗
11. Sato, K. & Hirotsu, Y. Magnetoanisotropy, long-range order parameter and thermal stability of isolated L10 FePt nanoparticles with mutual fixed orientation. J. Magn. Magn. Mater. 272–276, 1497–1499 (2004).10.1016/j.jmmm.2003.12.1044 ↗
12. Yasuda, H. & Mori, H. Effect of cluster size on the chemical ordering in nanometer-sized Au-75 at.%Cu alloy clusters. Z. Für Phys. D 37, 181–186 (1996).10.1007/s004600050026 ↗
13. Miyazaki, T. et al. Size effect on the ordering of L10 FePt nanoparticles. Phys. Rev. B 72, 144419 (2005).10.1103/PhysRevB.72.144419 ↗
14. Takahashi, Y. H., Ohkubo, T., Ohnuma, M. & Hono, K. Size effect on the ordering of FePt granular films. J. Appl. Phys. 93, 7166–7168 (2003).10.1063/1.1555895 ↗
15. Sato, K., Hirotsu, Y., Mori, H., Wang, Z. & Hirayama, T. Long-range order parameter of single L10–FePd nanoparticle determined by nanobeam electron diffraction: Particle size dependence of the order parameter. J. Appl. Phys. 98, 024308 (2005).10.1063/1.1985973 ↗
16. Yang, B., Asta, M., Mryasov, O. N., Klemmer, T. J. & Chantrell, R. W. The nature of A1–L10 ordering transitions in alloy nanoparticles: A Monte Carlo study. Acta Mater. 54, 4201–4211 (2006).10.1016/j.actamat.2006.05.013 ↗
17. Chepulskii, R. V. & Butler, W. H. Temperature and particle-size dependence of the equilibrium order parameter of FePt alloys. Phys. Rev. B 72, 134205 (2005).10.1103/PhysRevB.72.134205 ↗
18. Muller, M. & Albe, K. Lattice Monte Carlo simulations of FePt nanoparticles: Influence of size, composition, and surface segregation on order–disorder phenomena. Phys. Rev. B 72, 094203 (2005).10.1103/PhysRevB.72.094203 ↗
19. Moskovkin, P. et al. Model predictions and experimental characterization of Co–Pt alloy clusters. Eur. Phys. J. D 43, 27–32 (2007).10.1140/epjd/e2007-00066-0 ↗
20. Moskovkin, P. & Hou, M. Metropolis Monte Carlo predictions of free Co–Pt nanoclusters. J. Alloys Compounds 434–435, 550–554 (2007).10.1016/j.jallcom.2006.08.178 ↗
21. Le Bouar, Y., Loiseau, A. & Finel, A. Origin of the complex wetting behaviour in Co–Pt alloys. Phys. Rev. B 68, 224203 (2003).10.1103/PhysRevB.68.224203 ↗
22. Dai, Z. R., Sun, S. & Wang, Z. L. Phase transformation, coalescence, and twinning of monodisperse FePt nanocrystals. Nano Lett. 1, 443–447 (2001).10.1021/nl0100421 ↗
23. Yu, A. C. C., Mizuno, M., Sasaki, Y., Kondo, H. & Hiraga, K. Structural characteristics and magnetic properties of chemically synthesized CoPt nanoparticles. Appl. Phys. Lett. 81, 3768–3770 (2002).10.1063/1.1521569 ↗
24. Wang, A., Li, T., Zhou, Y., Jiang, H. & Zheng, W. Coupled Co–Pt nanoparticles in C matrix. Mater. Sci Eng. B 103, 118–121 (2003).10.1016/S0921-5107(03)00158-2 ↗
25. Zinke-Allmang, M., Feldman, L. C. & Grabow, M. H. Clustering on surfaces. Surf. Sci. Rep. 16, 377–463 (1992).10.1016/0167-5729(92)90006-W ↗
26. Alloyeau, D., Langlois, C., Ricolleau, C., Le Bouar, Y. & Loiseau, A. A TEM in situ experiment as a guideline for the synthesis of as-grown ordered CoPt nanoparticles. Nanotechnology 18, 375301 (2007).10.1088/0957-4484/18/37/375301 ↗
27. Alloyeau, D. et al. STEM nanodiffraction technique for structural analysis of CoPt nanoparticles. Ultramicroscopy 108, 656–662 (2008).10.1016/j.ultramic.2007.10.006 ↗
28. Rosato, V., Guillopé, M. & Legrand, B. Thermodynamical and structural properties of fcc transition metals using a simple tight-binding model. Phil. Mag. A 59, 321–336 (1989).10.1080/01418618908205062 ↗
29. Rossi, G., Ferrando, R. & Mottet, C. Structure and chemical ordering in CoPt nanoalloys. Faraday Discuss. 138, 193–210 (2008).10.1039/B705415G ↗
30. Tournus, F. et al. Evidence of L10 chemical order in CoPt nanoclusters: Direct observation and magnetic signature. Phys. Rev. B 77, 144411 (2008).10.1103/PhysRevB.77.144411 ↗
31. Langlois, C. et al. Growth and structural properties of CuAg and CoPt bimetallic nanoparticles. Faraday Discuss. 138, 375–391 (2008).10.1039/B705912B ↗
32. Rellinghaus, B. et al. On the L10 ordering kinetics in Fe–Pt nanoparticles. IEEE Trans. Magn. 42, 3048 (2006).10.1109/TMAG.2006.880087 ↗
33. Alloyeau, D. et al. Comparing electron tomography and HRTEM slicing methods as tools to measure the thickness of nanoparticles. Ultramicroscopy 109, 788–796 (2009).10.1016/j.ultramic.2009.02.002 ↗
34. Cliff, G. & Lorimer, G. W. The quantitative analysis of thin specimen. J. Microsc. 1032, 203–207 (1975).10.1111/j.1365-2818.1975.tb03895.x ↗
35. Van Cappellen, E. The parameterless correction method in X-ray microanalysis. Microsc. Microanal. Microstruct. 1, 1–22 (1990).10.1051/mmm:01990001010100 ↗