Browsing by Author "Jaime, Marcelo"
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Item Magnetic Nanopantograph in the SrCu₂(BO₃)₂ Shastry-Sutherland Lattice(National Academy of Sciences, 2015-02-02) Radtke, Guillaume; Saúl, Andrés; Dabkowska, Hanna A.; Salamon, Myron B.; Jaime, Marcelo; 0000 0001 0965 7058 (Salamon, MB); 79014293 (Salamon, MB); Salamon, Myron B.Magnetic materials having competing, i.e., frustrated, interactions can display magnetism prolific in intricate structures, discrete jumps, plateaus, and exotic spin states with increasing applied magnetic fields. When the associated elastic energy cost is not too expensive, this high potential can be enhanced by the existence of an omnipresent magnetoelastic coupling. Here we report experimental and theoretical evidence of a nonnegligible magnetoelastic coupling in one of these fascinating materials, SrCu₂(BO₃)₂ (SCBO). First, using pulsed-field transversal and longitudinal magnetostriction measurements we show that its physical dimensions, indeed, mimic closely its unusually rich field-induced magnetism. Second, using density functional-based calculations we find that the driving force behind the magnetoelastic coupling is the CuOCu superexchange angle that, due to the orthogonal Cu²⁺ dimers acting as pantographs, can shrink significantly (0.44%) with minute (0.01%) variations in the lattice parameters. With this original approach we also find a reduction of ~10% in the intradimer exchange integral J, enough to make predictions for the highly magnetized states and the effects of applied pressure on SCBO.Item Missing Magnetism in Sr₄Ru₃O₁₀: Indication for Antisymmetric Exchange Interaction(Nature Publishing Group, 2018-09-24) Weickert, Franziska; Civale, Leonardo; Maiorov, Boris; Jaime, Marcelo; Salamon, Myron B.; Carleschi, Emanuela; Strydom, Andre M.; Fittipaldi, Rosalba; Granata, Veronica; Vecchione, Antonio; Salamon, Myron B.Metamagnetism occuring inside a ferromagnetic phase is peculiar. Therefore, Sr₄Ru₃O₁₀, a T_C = 105 K ferromagnet, has attracted much attention in recent years, because it develops a pronounced metamagnetic anomaly below T_C for magnetic fields applied in the crystallographic ab-plane. The metamagnetic transition moves to higher fields for lower temperatures and splits into a double anomaly at critical fields H_{c1} = 2.3 T and H_{c2} = 2.8 T, respectively. Here, we report a detailed study of the different components of the magnetization vector as a function of temperature, applied magnetic field, and varying angle in Sr₄Ru₃O₁₀. We discover for the first time a reduction of the magnetic moment in the plane of rotation at the metamagnetic transition. The anomaly shifts to higher fields by rotating the field from H ⟂ c to H ∥ c. We compare our experimental findings with numerical simulations based on spin reorientation models taking into account magnetocrystalline anisotropy, Zeeman effect and antisymmetric exchange interactions. While Magnetocrystalline anisotropy combined with a Zeeman term are sufficient to explain a metamagnetic transition in Sr₄Ru₃O₁₀, a Dzyaloshinskii-Moriya term is crucial to account for the reduction of the magnetic moment as observed in the experiments.