Weak spin interactions in Mott insulating La2O2Fe2OSe2

Abstract

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Structural and magnetic characterization of iron oxyselenidesCe2O2Fe2OSe2andMcCabe1, Wills2, Chapon3 et al. 2014Phys. Rev. BSelf Cite139260View full textAdd to dashboardCite

“…Significant anisotropic peak broadening of magnetic Bragg reflections was observed for both Ce and Nd phases, similar to that observed for La 2 O 2 Fe 2 OSe 2 [25]. This could be modeled with an expression for antiphase boundaries perpendicular to the c axis [34,35], which gave a significantly improved fit to the data (Fig.…”

“…Interestingly, a similar 2-k model, composed of perpendicular AFM chains, has been predicted for the FeAs sheets in iron arsenides and oxyarsenides [27,28]. The recent studies on La 2 O 2 Fe 2 OSe 2 indicated the presence of antiphase boundaries or stacking faults perpendicular to the stacking direction and gave evidence for 2D-Ising-like magnetism within these sheets [25]. In the light of this work, it is timely to report a similar analysis on Ln 2 O 2 Fe 2 OSe 2 (Ln = Ce, Nd) analogs to test the robustness of the 2-k model to changes in Fe-O bond lengths and to a magnetic moment on the Ln site.…”

“…These Ln = Ce, Nd phases can be compared with Ln = La, Pr analogs and the expected decrease in unit cell parameters with decreasing Ln 3+ ionic radii is observed (1). [25]. For the Ce sample, at 96 K, some diffuse scattering is observed at a similar d spacing to the most intense magnetic Bragg reflection (see Supplemental Material [33]), suggesting some two-dimensional short-range ordering immediately above the transition to a three-dimensional AFM phase.…”

“…This has led to much research into the interplay between transition metal and lanthanide magnetic sublattices in these and related mixed-anion systems [7][8][9][10][11][12][13][14][15][16][17][18][19] [23] and a collinear model [10,22]. Recent work suggests that the 2-k model is the more likely [24][25][26]. In this magnetic structure (Fig.…”

Ising-nematic order in the bilinear-biquadratic model for the iron pnictides

“…Indeed, superconductivity was found to border a Mott insulating phase in alkaline iron selenides A 1−x Fe 2−y Se 2 (the "245" family, with A = K, Rb, Cs, or Tl) [24][25][26][27] . The Mott insulating ground state has also been identified in the iron oxychalcogenides La 2 O 3 Fe 2 (Se,S) 2 [28,29], R 2 O 3 Fe 2 Se 2 (here R = Ce,Pr,Nd,Sm) 30 , and Sr 2 F 2 Fe 2 OS 2 [31]. Further evidence in favor of proximity to the incipient Mott phase comes from the suppression of the Drude peak in optical conductivity measurements on iron pnictides 32,33 and the spectral weight transfer induced by temperature 34,35 .…”