9:30 AM - QT02.08.06
Epitaxial Growth of Mn3Sn on Sapphire Substrates Using Molecular Beam Epitaxy
Sneha Upadhyay1,Tyler Erickson1,David Ingram1,Fengyuan Yang2,Arthur Smith1
Ohio University1,The Ohio State University2
The Kagome antiferromagnet Mn3Sn has become fascinating in the current times because it’s one of the rare antiferromagnets that exhibits large anomalous Hall and Nernst effects. This opens a new area of research using functional antiferromagnets1, but this requires fabricating high-quality thin films. There are reports of the controlled growth of Mn3Sn on substrates like m-plane sapphire,2 MgO (111),3 Pt/Al2O3 (0001),4 and Si/SiO2,5 and surfaces have been prepared by cleaving bulk samples.6 For the grown films, one thing common in these reports is that all the samples were sputter deposited which often results in polycrystalline films. In this work, the goal is to grow a crystalline high quality Mn3Sn film using molecular beam epitaxy (MBE). Effusion cells are used for Mn and Sn sources which are calibrated using a quartz crystal thickness monitor. The growth is monitored in-situ using reflection high energy electron diffraction (RHEED) and measured ex-situ using X-ray diffraction and Rutherford backscattering. The samples are grown over a range of substrate temperatures (150-650 °C) and Mn:Sn flux ratios (1.0-4.0) and on different sapphire substrate orientations (c-plane, a-plane and m-plane) to develop an understanding of how to control the film orientation, crystalline quality, stoichiometry, and surface epitaxial smoothness. We also compare growth with and without using a 3 nm thick platinum buffer layer which was used recently by Cheng et al. to both achieve better epitaxial lattice match and to demonstrate a topological Hall effect.4 Our preliminary results show that highly crystalline thin films can be achieved via MBE growth at 650 °C with 3:1 stoichiometry and a highly streaky RHEED pattern showing 6-fold hexagonal crystal symmetry on c-plane sapphire substrates. Additional results pertaining to phase and crystallinity as a function of growth parameters will also be discussed.
1 Songtian Sonia Zhang, Jia-Xin Yin, Muhammad Ikhlas, Hung-Ju Tien, Rui Wang, Nana Shumiya, Guoqing Chang, Stepan S. Tsirkin, Youguo Shi, Changjiang Yi, Zurab Guguchia, Hang Li,Wenhong Wang, Tay-Rong Chang, Ziqiang Wang, Yi-feng Yang, Titus Neupert, Satoru Nakatsuji, and M. Zahid Hasan, "Many body resonance in a correlated topological Kagome Antiferromagnet", Physical Review Letters 125, 046401 (2020).
2 Seungjun Oh, Tadashi Morita, Tomoki Ikeda, Masakiyo Tsunoda, Mikihiko Oogane and Yasuo Ando,"Controlled growth and magnetic property of a-plane oriented Mn3Sn thin film", AIP Advances 9, 035109 (2019).
3 Tomoki Ikeda, Masakiyo Tsunoda, Mikihiko Oogane, Seungjun Oh, Tadashi Morita and Yasuo Ando, “Fabrication and evaluation of highly c-plane oriented Mn3Sn thin films ", AIP Advances 10, 015310 (2020)
4 Yang Cheng, Sisheng Yu, Menglin Zhu, Jinwoo Hwang, and Fengyuan Yang, "Tunable Topological Hall effects in noncollinear antiferromagnets Mn3Sn/Pt bilayers", APL Materials 9,051121 (2021).
5 Tomoya Higo, Danru Qu, Yufan Li, C. L. Chien, Yoshichika Otani, and Satoru Nakatsuji, "Anomalous Hall effect in thin films of the Weyl antiferromagnet Mn3Sn", Appl. Phys. Lett. 113, 202402 (2018).
6 Hung-Hsiang Yang, Chi-Cheng Lee, Yasuo Yoshida, Muhammad Ikhlas, Takahiro Tomita, Agustinus Nugroho, Taisuke Ozaki, Satoru Nakatsuji & Yukio Hasegawa, “Scanning tunneling microscopy on cleaved Mn3Sn (0001) surface”, Scientific Reports 9, 1 (2019).
*The authors acknowledge support from the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award No. DE-FG02-06ER46317.