Unusual Effects in Transport and Magnetism of Layered AFM Semimetals - The Emergence of Ferromagnetism Due to Nanodefects

Attend a research seminar exploring unusual transport and magnetic properties in layered antiferromagnetic semimetals, with particular focus on how nanodefects can induce ferromagnetism in these materials. Learn about the puzzling behaviors observed in stoichiometric semimetallic layered antiferromagnets including MnBi₂Te₄, EuRbFe₄As₄, EuIn₂As₂, EuCd₂As₂, EuSn₂As₂, EuFe₂As₂, EuSn₂P₂, and EuMg₂Bi₂, where electrons or Cooper pairs propagate through alternating magnetic fields of AFM-ordered host lattices. Discover the novel exchange splitting mechanism that explains the isotropic negative magnetoresistance correlated with magnetization observed in non-Weyl semimetals. Examine the weak nonlinearity and hysteresis in DC-magnetization measurements at low fields, along with the upturn in AC susceptibility at lowest temperatures. Explore transmission electron microscopy investigations of EuSn₂As₂ single crystals that revealed monolayer thick planar defects with local composition EuSnAs₂, containing extra Eu atoms and missing Sn atoms. Understand how these defects form supercells identified as Eu₇Sn₁₂As₁₄ with odd numbers of Eu atoms and non-zero magnetic moments. Review density functional theory calculations confirming ferromagnetic ordering in defect layers and learn about the two-phase model describing FM-defects embedded in AFM host lattices. Gain insights into how this parameter-free model successfully explains temperature and magnetic field dependencies observed in electron spin resonance measurements and other experimental features.