Orthogonal Spin Arrangement in Quasi-Two-Dimensional La₂Co₂O₃Se₂

Abstract

The crystal, electronic, and magnetic structures of the cobalt oxyselenide La(2)Co(2)O(3)Se(2) were investigated through powder neutron diffraction measurements and band structure calculations. This oxyselenide crystallizes in a tetragonal layered structure with space group I4/mmm. The Co ion is sixfold-coordinated by two oxide ions and four selenide ions, and the face-sharing CoO(2)Se(4) octahedra form Co(2)OSe(2) layers. The band structure calculations revealed that the Co ion is in the divalent high-spin state. Rietveld analysis of the neutron diffraction profiles below 200 K demonstrated that the Co moments have a noncollinear antiferromagnetic structure with the propagation vector k = (½, ½, 0). The ordered magnetic moment was determined to be 3.5 μ(B) at 10 K, and the directions of the nearest-neighbor Co moments are orthogonal each other in the c plane.

Weak spin interactions in Mott insulating La2O2Fe2OSe2McCabe1, Stock2, Rodriguez3 et al. 2014Phys. Rev. B4527630View full textAdd to dashboardCite

“…The FM J 2 Fe-Se-Fe interactions, predicted by DFT, are consistent with the FM chain structure reported for Ce 2 O 2 FeSe 2 [43]. 2D exchange concomitant with magnetocrystalline anisotropy (due to partially unquenched orbital angular momentum) is likely to stabilize the 2-k structure [and the k = ( 1 2 1 2 0) structure reported for La 2 O 2 Co 2 OSe 2 ] [27,31]. This agrees with the Ising-like character suggested to constrain M 2+ moments to lie along perpendicular local axes within the ab plane for M = Fe, Co (i.e., along Fe-O bonds in La 2 O 2 Fe 2 OSe 2 ).…”

“…This magnetic order parameter is shown in Fig. 1(d) with critical exponent β Fe = 0.122(1), similar to the 2D-Ising-like behavior of La 2 O 2 Co 2 OSe 2 and BaFe 2 As 2 [31,32]. This is in contrast to the Mn analog with an exponent β = 0.24(3) [ Fig.…”

“…The magnetic Bragg reflections observed for La 2 O 2 Fe 2 OSe 2 are anisotropically broadened similarly to Sr 2 F 2 Fe 2 OS 2 , suggesting that both have similar magnetic microstructures. This peak broadening can be described by an expression for antiphase boundaries perpendicular to the c axis [29] [27,30,31].…”

Crystal field excitations and magnons: Their roles in oxyselenides Pr2O2M2OSe2(

“…The La 2 O 2 M 2 OSe 2 (M = Mn, Fe, Co) oxyselenides order antiferromagnetically on cooling (T N = 160-168 K, 89 K, and 220 K for Mn [13][14][15], Fe [16,17], and Co [18][19][20] analogues, respectively). There are three magnetic exchange interactions in the M 2 O layers: nearest-neighbor (nn) AFM exchange J 1 , next-nearest-neighbor (nnn) 180°M-O-M AFM exchange J 2 and nnn ∼ 97…”

Magnetism in La2O3(Fe1−xMnLei1, Božin2, Llobet3 et al. 2012Phys. Rev. B

“…2,3 Recently, a family of layered TMP oxychalcogenides Ln 2 O 3 TM 2 Ch 2 (Ln = rare earth, TM = transition metal, and Ch = S, Se) and its analogues A 2 F 2 TM 2 OCh 2 (A = Sr, Ba)(2322) has received more attention. [4][5][6][7][8][9][10][11][12][13][14][15][16] 2− layers transition metal atoms are located at the distorted octahedral environment due to the different distances of TM-Ch and TM-O, whereas the TM-Ch(O) octahedrons are face sharing. This distortion lifts the degeneracy of e g and t 2g levels in a non-distorted octahedral crystal field.…”