| Time：1121207 (Thur.) 12:20~13:20 Speaker：Madhav Prasad Ghimire Professor, Central Department of Physics, Tribhuvan University, Nepal & Leibniz IFW-Dresden, Germany Title：Electronic structure, Magnetism, and Topological Aspects of Double Perovskites and Layered Materials Abstract： In recent years, perovskite oxides have been widely investigated due to their interesting properties useful for possible applications, for example, in multifunctional devices. We propose several materials tailoring first on a Mott insulator, say Pr2MgIrO6 (PMIO), exploiting the cooperative effect from Coulomb interaction, spin-orbit coupling (SOC) and the crystal field [1]. In the first part of my talk, I will introduce our efforts in several group of double perovskite oxides A2M1−xM’xTO6 that we explore for the realization of the topological electronic structure derived from the transition metals [2, 3]. We demonstrated that replacing one of the magnetic ions, say Cr by Ni, or hole doping onto the A-site, one can achieve several half metals (HMs) which can be an ideal candidate for spintronics. I will highlight the role of density functional theory (DFT) in substantiating and clarifying the origin of these band features which supports our experimental findings, and further discuss how magnetic anisotropy energy varies with chemical doping. Second part of my talk willfocus on the identification/realization of topological phases in Bi14Rh3I9 and Bi12Rh3Sn3I9. The fundamental difference between Bi14Rh3I9 and Bi12Rh3Sn3I9 [4,5] lies in the composition and the arrangement of the anionic spacer. I will try to elaborate how the effects of iodine deposition as a sparse overlayer and of counter-doping by exchanging surface layer Bi atoms by Sn in Bi14Rh3I9 [4] can lead to novel topological phase. Additionally, I will discuss the cleavage energy can be estimated in 2D materials by DFT approach [6]. If time permits, I will briefly discuss how magnetization drives creation and annihilation of Weyl points Co3Sn2S2 [7], and the identification/observation of Dirac points and flat band in kagome metal FeSn [8]. At the end I will introduce our AMRL group’s recent progress on research in other fields. References : [1] Ghimire et al. Phys. Rev. B 93, 134421 (2016). [2] Feng et al., Phys. Rev. B 94, 235158 (2016); Feng et al., Phys. Rev. Mat. 3, 124404 (2019). [3] Bhandari et al., RSC Adv. 10, 16179 (2020). [4] M. P. Ghimire and M. Richter, Nano Lett. 17, 6303 (2017). [5] Anh et al., Chem. Eur. J. 26, 15549 (2020). [6] Rasche et al., Nano Lett. 22, 3550 (2022). [7] M. P. Ghimire, J. I. Facio et al., Phys. Rev. Res. 1 032044(R) (2022). [8] M. Kang, L. Ye, … M. P. Ghimire et al., Nat. Mater. 19 163-169 (2020). Place：F104, Gongguan Campus, NTNU |
