As a recent successfully exfoliated non-van der Waals layered material, AgCrSsub.2 has received a lot of attention. Motivated by its structure-related magnetic and ferroelectric behavior, a ...theoretical study on its exfoliated monolayer AgCrsub.2Ssub.4 has been carried out in the present work. Based on density functional theory, the ground state and magnetic order of monolayer AgCrsub.2Ssub.4 have been determined. The centrosymmetry emerges upon two-dimensional confinement and thus eliminates the bulk polarity. Moreover, two-dimensional ferromagnetism appears in the CrSsub.2 layer of AgCrsub.2Ssub.4 and can persist up to room temperature. The surface adsorption has also been taken into consideration, which shows a nonmonotonic effect on the ionic conductivity through ion displacement of the interlayer Ag, but has little impact on the layered magnetic structure.
Mixed-valent Basub.2Mnsup.2+Mnsub.2 sup.3+(SeOsub.3)sub.6 crystallizes in a monoclinic P2sub.1/c structure and has honeycomb layers of Mnsup.3+ ions alternating with triangular layers of Mnsup.2+ ...ions. We established the key parameters governing its magnetic structure by magnetization M and specific heat Csub.p measurements. The title compound exhibits a close succession of a short-range correlation order at Tcorr = 10.1 ± 0.1 K and a long-range Néel order at TN = 5.7 ± 0.1 K, and exhibits a metamagnetic phase transition at T < TN with hysteresis most pronounced at low temperatures. The causes for these observations were found using the spin exchange parameters evaluated by density functional theory calculations. The title compound represents a unique case in which uniform chains of integer spin Mnsup.3+ (S = 2) ions interact with those of half-integer spin Mnsup.2+ (S = 5/2) ions.
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