Low temperatureGd 3+ ESR linewidth behavior inGd 0.75 Y 0.25 Ba 2 Cu 3 O 7−δ powder

Filip, Claudiu; Giurgiu, L. M.; Filip, Xenia; Kessler, C.; Mehring, M.

doi:10.1007/bf02583879

Cited by 3 publications

(9 citation statements)

References 5 publications

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“…A linear correlation is evident just above T CO , analogous to that expected near Néel temperature for AFM spin fluctuations. 28 We determined m = − 0.12 in agreement with that found in other layered compounds where the Gd 3+ spin dynamics is affected by 3d metal spins fluctuations. 28,29 Spin fluctuations above T CO as revealed by EPR can be then considered precursors of magnetic transition at T CO .…”

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confidence: 87%

“…28 We determined m = − 0.12 in agreement with that found in other layered compounds where the Gd 3+ spin dynamics is affected by 3d metal spins fluctuations. 28,29 Spin fluctuations above T CO as revealed by EPR can be then considered precursors of magnetic transition at T CO . 28 This gives a new insight to reappoint the actual T N in LnBaCo 2 O 5 system.…”

supporting

confidence: 87%

“…The EPR line broadening while decreasing T has been interpreted as a precursor behavior of AFM transitions. 28,29 According to available theories, 28 the critical increase of H pp due to AFM spin fluctuations can be described by the relation…”

mentioning

confidence: 99%

“…28,29 Spin fluctuations above T CO as revealed by EPR can be then considered precursors of magnetic transition at T CO . 28 This gives a new insight to reappoint the actual T N in LnBaCo 2 O 5 system. Indeed, we propose that the weak upturn at 365 K is more related to the onset of short-range CO giving rise to AFM spin fluctuations between the partially ordered Co.…”

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confidence: 99%

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Charge ordering transition in GdBaCo2O5: Evidence of reentrant behavior

et al. 2013

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We present a detailed study on the charge ordering transition in a GdBaCo 2 O 5.0 system by combining highresolution synchrotron powder/single-crystal diffraction with electron paramagnetic resonance experiments as a function of temperature. We found a second-order structural phase transition at T CO = 247 K (Pmmm to Pmma) associated with the onset of long-range charge ordering. At T min ≈ 1.2T CO, the electron paramagnetic resonance linewidth rapidly broadens, providing evidence of antiferromagnetic spin fluctuations. This likely indicates that, analogously to manganites, the long-range antiferromagnetic order in GdBaCo 2 O 5.0 sets in at ≈T CO . Pair distribution function analysis of diffraction data revealed signatures of structural inhomogeneities at low temperature. By comparing the average and local bond valences, we found that above T CO the local structure is consistent with a fully random occupation of Co 2+ and Co 3+ in a 1:1 ratio and with a complete charge ordering below T CO . Below T ≈ 100 K the charge localization is partially melted at the local scale, suggesting a reentrant behavior of charge ordering. This result is supported by the weakening of superstructure reflections and the temperature evolution of electron paramagnetic resonance linewidth that is consistent with paramagnetic reentrant behavior reported in the GdBaCo 2 O 5.5 parent compound.

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supporting

confidence: 87%

supporting

confidence: 87%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Charge ordering transition in GdBaCo2O5: Evidence of reentrant behavior

et al. 2013

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“…This critical temperature matches with T N2 of the AFM1-AFM2 transition inferred from muon spin relaxation measurements in cobaltites with δ ∼ 0.5 [13]. Here we provide evidence that the same transition occurs in GBCO at T N2 ∼ 210 K. This is also confirmed by the fast broadening of the ESR linewidth observed above T N2 described by the critical equation [4,33] H pp = a[(T − T N2 )/T N2 ] −m , where a and m are constants. Experimental data were fitted in the two linear regimes, with m = −0.5 and −0.1, observed in the log-log plot of H pp [inset to Fig.…”

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confidence: 87%

Interplay of structural and magnetic nanoscale phase separation in layered cobaltites

et al. 2015

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We report on the structural, electronic, and magnetic phases of a previously unexplored region in the phase diagram of GdBaCo 2 O 5+δ (δ = 0.57 and 0.63). Despite a homogenous average structure displayed by both the samples, the orthorhombic highly oxygenated GdBaCo 2 O 5.63 shows clear signatures of structural nanoscale phase separation. By combining a pair distribution function with photoluminescence and electron spin resonance techniques, we found that the nanoscale phase separation is induced by an inhomogeneous distribution of ferromagnetic Co 3+ − Co 4+ clusters embedded in an antiferromagnetic Co 3+-rich matrix. In addition, we uncovered a phase evolution involving the collapse of the orthorhombic strain below room temperature. The origin of this noncanonical transition seems to be associated with the interplay of the observed nanoscale phase separation and a new magnetic phase transition occurring below T ∼ 180 K.

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