Abstract
Magnetic properties can be manipulated to enhance certain functionalities by tuning different material processing parameters. Here, we present the controllable magnetization steps of hysteresis loops in double-perovskite single crystals of Eu2CoMnO6. Ferromagnetic order emerges below TC ≈ 122 K along the crystallographic c axis. The difficulty in altering Co2+ and Mn4+ ions naturally induces additional antiferromagnetic clusters in this system. Annealing the crystals in different gas environments modifies the mixed magnetic state, and results in the retardation (after O2-annealing) and bifurcation (after Ar-annealing) of the magnetization steps of isothermal magnetization. This remarkable variation offers an efficient approach for improving the magnetic properties of double-perovskite oxides.
Highlights
Magnetic oxides composed of metal cations and oxygen anions are extensively studied due to the abundance of the elements and stability of the compounds
The incomplete alteration of Co2+ and Mn4+ ions naturally results in additional antiferromagnetic clusters which correspond to anti-sites of ionic disorders and/or antiphase boundaries that lead to C o2+–Co2+ or M n4+–Mn4+ pairs[24,25]
We have confirmed that the ferromagnetic order in ECMO single crystals appears along the crystallographic c axis at TC = 122 K
Summary
Magnetic oxides composed of metal cations and oxygen anions are extensively studied due to the abundance of the elements and stability of the compounds. Double-perovskite oxides, in which transition metal ions are alternatingly located in octahedral oxygen environments, have been broadly investigated because of their fascinating magnetic properties These properties include exchange b ias[6,7,8], magnetocaloric effect[9,10,11,12], and m ultiferroicity[13,14,15,16,17]. In Gd2CoMnO6 and Tb2CoMnO6, the orders of large rare-earth magnetic moments of Gd3+ and Tb3+ at TGd = 21 K and TTb = 15 K, respectively, reveal the giant anisotropic magnetocaloric effects[9,10,32] It is evident from the previous investigations that a detailed understanding of distinct magnetic phases and interactions is essential for examining functional properties in double perovskites. Our results establish that the atmospheric environments in post-annealing play an important role in modifying the magnetic properties in mixed-valent double-perovskite magnets
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