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  Podlesnyak, A.; Russina, M.; Furrer, A.; Alfonsov, A.; Vavilova. E.; Kataev, V.; Büchner, B.; Strässle, Th.; Pomjakushina, E.; Conder, K.; Khomskii, D.I.: Spin-state polarons in lightly-hole-doped LaCoO₃. Physical Review Letters 101 (2008), p. 247603/1-4

10.1103/PhysRevLett.101.247603

Abstract:
Inelastic neutron scattering (INS), electron spin resonance (ESR), and nuclear magnetic resonance (NMR) measurements were employed to establish the origin of the strong magnetic signal in lightly-holedoped La1
xSrxCoO3, x  0:002. Both INS and ESR low temperature spectra show intense excitations with large effective g factors 10–18. NMR data indicate the creation of extended magnetic clusters. From the Q dependence of the INS magnetic intensity, we conclude that the observed anomalies are caused by the formation of octahedrally shaped spin-state polarons comprising seven Co ions. The present INS, ESR, and NMR data give evidence for two regimes in the lightly-hole-doped samples: (i) T <35 K dominated by spin polarons; (ii) T >35 K dominated by thermally activated magnetic Co3þ ions.