Berlin 2024 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 15: Topological Insulators and Weyl Semimetals (joint session MA/TT)
MA 15.9: Vortrag
Dienstag, 19. März 2024, 11:45–12:00, H 2013
Interplay of magnetism and band topology in Eu1−xCaxMg2Bi2 (x=0, 0.5, 0.67) from first principles study — •Amarjyoti Choudhury, Narayan Mohanta, and Tulika Maitra — IIT Roorkee,India
The recent discovery of time-reversal symmetry-breaking magnetic Weyl semimetals (WSMs) has sparked extensive research in quantum topological materials. We systematically studied magnetic orders, electronic structure, and the interplay between magnetic order and band topology in EuMg2Bi2 (EMB) and its Ca-doped variant using density functional theory (DFT). Our investigation reveals various magnetic order-driven topological phases, such as a topological insulator in the A-type antiferromagnetic (A-AFM) phase with Eu moments along the b, a Dirac semimetal in the A-AFM phase with Eu moments along the c direction, and a Weyl semimetal in the ferromagnetic (FM) phase with Eu moments along the c direction. These phases are energetically close and tunable by external factors like magnetic field or chemical substitution. In the FM state of EuMg2Bi2, we identify an ideal Weyl semimetal with a single pair of Weyl points (WPs) close to the Fermi level along Γ-A direction. Doping with 50% and 67% Ca at Eu sites moves the WPs even closer to the Fermi level, making it highly desirable for applications. Additionally, the separation between WPs decreases in doped compounds, impacting anomalous Hall conductivity (AHC). Our first-principles calculation of AHC shows high peak values at these WPs, decreasing with Ca doping, indicating Ca as a potential external handle to tune AHC in this system.
Keywords: AFM Topological Insulator; Dirac semimetal,Weyl semimetal; Topological phases are magnetic order driven; A single pair of Weyl points in FMc state; anomalous Hall conductivity (AHC)