Weak Pair Exchange Interactions between Cobalt Ions in Quasi‐One‐Dimensional Antiferromagnet CsCoCl₃

Abstract

The EPR spectra of single Co2+ ions and Co2+-Co2+ pairs in CsMg,-,Co,Cl, (x = O.OOO1 to 0.04) in Xand Q-bands are investigated. One type of single Co2+ spectra and four types of additional spectra attributed to Co2+-Coz+ pairs coupled by weak spin-spin interaction are observed. Using computer simulation of EPR spectra the parameters of spin-spin interaction are determined. The observed EPR spectra and the expected pair Co2+-Co2+ interactions in CsMg, _,Co,Cl, are analysed. The exchange parameters for the nearest neighbour Coz+-Coz+ pairs in the ab-plane are estimated. Thenature of the exchange anisotropy is discussed. MeTOAOM 3nP B x-H Q-~pianaso~ax HCCJEAOBaHbI CIIeKTpbI 3nP ORHHOYHbIX UOHOB c O z + H IIap c o 2 + -coz + B CsMg, -,CO,c~, (x = 0,0001 A0 0,04). 06HapyXeHbI OaUH THE CIIeKTpOB OAUHOYHbIX UOHOB c O z ' H WTbIpe THIIa ,L(OIIOJIHWTeJIbHbIX CIIeKTpOB, OTHeCeHHbIX K IIapaM UOHOB cOz+-c02+, CBR3aHHbIX CJIa6bIM CIIHH-CnUHOBbIM B3aUMOAe$kTBHeM. BCIIOJlb3yR MaIIIUHHOe MOAeJIHpOBaHHe CIIeKTpOB 3nP OIIpeAeneHbI napaMeTpbI CnEiH+XIHHOBOTO B3aBMOAekTBUR. npOaHaJIH3UpOBaHbI B03MOXHbIe BapUaHTbI OTHeCeHHR Ha6JIlOoAaeMbI CneKTpOB K OXHAaeMbIM IIapHbIM B3aEiMOAekT-BHRM c02+-c02+ OqeHeHbI 06MeHHbIe IIapaMeTpbI AJIR 6n~xaiiruux napc02 + -c02 + B IIJIOCKOCTH ab. 06CyXAeHa IIpUpOAa aHU30TpOIIHH 06MeHa. B CsMg, -,c0,c13. K:=-' = -1.618 K$;d = Kd-d = 0.097 K2z-d = -0.202 K ; i d = K:Y-d = 0.012 K:Ld = 0.062 K:Ld = 0.007 K $ i d = -0.014 K:*-' = 0.026 K $ i d = -0.009 K:y-d = 0.006 K$z-d = -0.018 K:Ld = -0.060 K:id = K:Y-d KtZ-' = -0.007 K$y-d = 0.003 K : i d = -0.014 YY = 0.004 K;Cd = -0.002

Synthesis, structure, and characterisation of a ferromagnetically coupled dinuclear complex containing Co(ii) ions in a high spin configuration and thiodiacetate and phenanthroline as ligands and of a series of isomorphous heterodinuclear complexes containing different Co : Zn ratios

“…27 and in the quasi-one-dimensional antiferromagnet CsCoCl 3 . 48 The powder EPR spectrum for 2 (Fig. 5) shows EPR features that mainly correspond to the above-described dinuclear S′ = 1 species but are much broadened by extended dipolar interactions.…”

“…[42][43][44][45][46] Furthermore, the exchange interactions that couple mononuclear Co(II) centres in extended lattices are usually below ∼3 cm −1 , and hence usually not detected or poorly discriminated with the most usual experimental techniques, with the only exception being EPR. 20,27,47,48 Less information is available about the electronic and magnetic properties of dinuclear Co(II) complexes and the role played by the chemical links between the Co(II) ions (intra-and inter-dimers) in transmitting exchange interactions. Dinuclear Co(II) complexes are usually bridged by composite links of different natures that transmit exchange interactions below ∼5 cm −1 .…”

“…42–46 Furthermore, the exchange interactions that couple mononuclear Co( ii ) centres in extended lattices are usually below ∼3 cm −1 , and hence usually not detected or poorly discriminated with the most usual experimental techniques, with the only exception being EPR. 20,27,47,48…”