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Perpendicularly magnetized Mn-based binary alloy epitaxial films on GaAs - Jianhua Zhao - Vendredi 30 octobre 2015 à 10 h

INSP - 4 place Jussieu - 75252 PARIS Cedex 05 - Barre 22-12 - 4e étage, salle 426

Jianhua Zhao - State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences


Ferromagnetic films with both high perpendicular anisotropy and good compatibility with semiconductors have great potential not only in semiconductor spintronic devices, like spin light-emitting diodes, spin field-effect transistors, and lateral spin valves with perpendicular spin injectors, but also in high-density integration of metallic spintronic functional devices like nonvolatile magnetoresistive random access memory (MRAM) on semiconductor circuits. Furthermore, ferromagnetic films with high perpendicular magnetic anisotropy (PMA) and magnetic energy product could be admirable for ultrahigh-density magnetic recording and permanent magnets. As the most promising candidates for such potential application, perpendicularly magnetized Mn-based binary alloys, like L10-MnGa and L10-MnAl have attracted special attention in recent years. However, although the growth and characterization of them have been studied intensively on various substrates in the past decades, only a few films on GaAs or MgO experimentally demonstrated PMA and relatively small coercivity (Hc). The quest for L10-MnGa and L10-MnAl films with the fascinating theory-predicted properties remains a major challenge [1].

Recently we have successfully grown high-quality Mn-based binary alloy, L10-MnxGa and L10-MnxAl single crystalline films with giant PMA on GaAs by molecular-beam epitaxy. In this presentation, After a brief introduction to their fascinating room-temperature magnetic properties, including ultrahigh coercivity, giant perpendicular anisotropy and large energy products [2,3], I will introduce how to tailor their magnetism by adjusting the composition, growth parameters and post-growth annealing conditions [3,4]. Then, I will present the anomalous transport behaviors in L10-Mn1.5Ga with variable chemical ordering [5]. Finally, I will mention the orbital two-channel Kondo effect existing in ferromagnetic L10-MnAl [6]. Our experimental data indicate that these two noble-metal-free and rare-earth-free perpendicularly magnetized materials could be used not only in semiconductor spintronic devices with high thermal stability and magnetic noise immunity, but also in ultrahigh-density magnetic storage and permanent magnets.

References : [1] L. J. Zhu, and J. H. Zhao, Appl. Phys. A 111 (2013) 379
[2] L. J. Zhu, S. H. Nie, K. K. Meng, D. Pan, J. H. Zhao and H. Z. Zheng, Adv. Mater. 24(2012) 4547
[3] L. J. Zhu, D. Pan, S. H. Nie, J. Lu and J. H. Zhao, Appl. Phys. Lett. 102 (2013) 132403
[4] S. H. Nie, L. J. Zhu, J. Lu, D. Pan, H. L. Wang, X. Z. Yu, J. X. Xiao and J. H. Zhao, Appl. Phys. Lett. 102 (2013) 152405
[5] L. J. Zhu, D. Pan and J. H. Zhao, Phys. Rev. B 89 (Rapid Communication) (2014) 220406(R)
[6] L. J. Zhu, S. H. Nie, P. Xiong, P. Schlottmann and J. H. Zhao, Nat. Commun. (under consideration)