Interplay of rare earth and iron magnetism in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>R</mml:mi><mml:mtext>FeAsO</mml:mtext></mml:mrow></mml:math>(<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>R</mml:mi><mml:mo>=</mml:mo><mml:mtext>La</mml:mtext></mml:mrow></mml:math>, Ce, Pr, and Sm): Muon-spin relaxation study and symmetry analysis

Maeter, H.; Luetkens, H.; Pashkevich, Yu. G.; Kwadrin, Andrej; Khasanov, R.; Amato, A.; Gusev, Alexander; Lamonova, K. V.; Chervinskii, D. A.; Klingeler, R.; Heß, Christian; Behr, G.; Büchner, B.; Klauß, H.‐H.

doi:10.1103/physrevb.80.094524

Cited by 144 publications

(299 citation statements)

References 51 publications

(128 reference statements)

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“…Both the FM and AF transitions are evident in the temperature derivative of the resistance but do not result in large anomalies as observed for RFeAsO. In the RFeAsO materials the Fe spins order in a striped pattern with a small ordered moment of ϳ0.4 B for all R from spectroscopic methods such as Mossbauer and SR. 25 Neutron powder diffraction, in contrast, suggests a wider spread of 0.3-0.8 B , 26 which Maeter et al have attributed to an induced magnetization on the R sublattice below T SDW that contributes to the "Fe" magnetic Bragg reflections. 25 It is not clear from our measurements whether this is important but the almost constant Co moment between 1.7 and 40 K ͑ ϳ0.3 B ͒ suggests that there is no significant induced "Nd contribution."…”

Section: Discussionmentioning

confidence: 99%

“…In the RFeAsO materials the Fe spins order in a striped pattern with a small ordered moment of ϳ0.4 B for all R from spectroscopic methods such as Mossbauer and SR. 25 Neutron powder diffraction, in contrast, suggests a wider spread of 0.3-0.8 B , 26 which Maeter et al have attributed to an induced magnetization on the R sublattice below T SDW that contributes to the "Fe" magnetic Bragg reflections. 25 It is not clear from our measurements whether this is important but the almost constant Co moment between 1.7 and 40 K ͑ ϳ0.3 B ͒ suggests that there is no significant induced "Nd contribution." The spectroscopic measurements also suggest that the R spin ordering does not have any effect on the magnitude of the Fe moment, while for neutron powder diffraction increases have been reported, in particular, for R = Nd.…”

Section: Discussionmentioning

confidence: 99%

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Superconductivity inNdFe1−xCoxAsO(

et al. 2010

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The phase diagram of NdFe 1−x Co x AsO for low cobalt substitution consists of a superconducting dome ͑0.05Ͻ x Ͻ 0.20͒ with a maximum critical temperature of 16.5͑2͒ K for x = 0.12. The x = 1 end member, NdCoAsO, is an itinerant ferromagnet ͑T C =85 K͒ with an ordered moment of 0.30͑1͒ B at 15 K. Below T N = 9 K, Nd spin ordering results in the antiferromagnetic coupling of the existing ferromagnetic planes. Rietveld analysis reveals that the electronically important twofold tetrahedral angle increases from 111.4°to 115.7°in this series. Underdoped samples with x = 0.046͑2͒ and x = 0.065͑2͒ show distortions to the orthorhombic Cmma structure at 72͑2͒ and 64͑2͒ K, respectively. The temperature dependences of the critical fields H c2 ͑T͒ near T c are linear with almost identical slopes of 2.3͑1͒ T K −1 for x = 0.065͑2͒, x = 0.118͑2͒, and x = 0.172͑2͒. The estimated critical field H c2 ͑0͒ and correlation length for optimally doped samples are 26͑1͒ T and 36͑1͒ Å. A comparison of the maximum reported critical temperatures of well-characterized cobalt-doped 122-and 1111-type superconductors is presented.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Superconductivity inNdFe1−xCoxAsO(

et al. 2010

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“…It was observed in the isostructural PrFeAsO where the in-plane stripe-like Fe AFM order is preserved but the Fe moments rotate to out-of-plane collinear AFM order below T Pr ≈ 11 K via Pr-Fe interaction. 11,14 Note that whereas the long-range Pr moments point along the c axis and the Fe moments rotate toward that axis in PrFeAsO, the long-range Ce moments are in the ab plane as discussed below and the Fe moments rotate in the ab plane in CeFeAsO, possibly reflecting the magnetic anisotropy of Fe sublattice by Ce magnetism via the Ce-Fe interaction in CeFeAsO. Based on our analysis, we cannot rule out the possibility that short-range Ce ordering slightly contributes to the anomaly at T * .…”

Section: Ce L Ii Rxms Measurementsmentioning

confidence: 99%

“…However, magnetization, resistivity and heat capacity measurements on polycrystalline 12 and single-crystalline 13 CeFeAsO have been interpreted in terms of very weak or no Ce-Fe exchange coupling. It is interesting to point out that as an outcome of the Pr-Fe coupling, the isostructural PrFeAsO exhibits temperature-induced Fe spin reorientation, 11,14 whereas for LaFeAsO involving nonmagnetic La, the Fe moments are fixed to be along the a axis even at low temperatures. 15 Moreover, temperature-induced Fe spin reorientation transition has been observed in few nonpnictide compounds involving rare-earth R and Fe sublattices, such as RFeO 3 , 16 RFe 2 , 16 RFe 11 Ti, 17 and R 2 Fe 14 B.…”

Section: Introductionmentioning

confidence: 99%

Magnetic structures and interplay between rare-earth Ce and Fe magnetism in single-crystal CeFeAsO

Zhang

Kim

et al. 2013

Phys. Rev. B

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Neutron and synchrotron resonant x-ray magnetic scattering (RXMS) complemented by heat capacity and resistivity measurements reveal the evolution of the magnetic structures of Fe and Ce sublattices in a CeFeAsO single crystal. The RXMS of magnetic reflections at the Ce L-II edge shows a magnetic transition that is specific to the Ce antiferromagnetic long-range ordering at T-Ce approximate to 4 K with short-range Ce ordering above T-Ce, whereas neutron diffraction measurements of a few magnetic reflections indicate a transition at T* approximate to 12 K with an unusual order parameter. Detailed order-parameter measurements on several magnetic reflections by neutrons show a weak anomaly at 4 K that we associate with the Ce ordering. The successive transitions at T-Ce and T* can also be clearly identified by two anomalies in heat capacity and resistivity measurements. The higher transition temperature at T* approximate to 12 K is mainly ascribed to Fe spin reorientation transition, below which Fe spins rotate uniformly and gradually in the ab plane. The Fe spin reorientation transition and short-range Ce ordering above T-Ce reflect the strong FeCe couplings prior to long-range ordering of the Ce. The evolution of the intricate magnetic structures in CeFeAsO going through T* and T-Ce is proposed. Neutron and synchrotron resonant x-ray magnetic scattering (RXMS) complemented by heat capacity and resistivity measurements reveal the evolution of the magnetic structures of Fe and Ce sublattices in a CeFeAsO single crystal. The RXMS of magnetic reflections at the Ce L II edge shows a magnetic transition that is specific to the Ce antiferromagnetic long-range ordering at T Ce ≈ 4 K with short-range Ce ordering above T Ce , whereas neutron diffraction measurements of a few magnetic reflections indicate a transition at T * ≈ 12 K with an unusual order parameter. Detailed order-parameter measurements on several magnetic reflections by neutrons show a weak anomaly at 4 K that we associate with the Ce ordering. The successive transitions at T Ce and T * can also be clearly identified by two anomalies in heat capacity and resistivity measurements. The higher transition temperature at T * ≈ 12 K is mainly ascribed to Fe spin reorientation transition, below which Fe spins rotate uniformly and gradually in the ab plane. The Fe spin reorientation transition and short-range Ce ordering above T Ce reflect the strong Fe-Ce couplings prior to long-range ordering of the Ce. The evolution of the intricate magnetic structures in CeFeAsO going through T * and T Ce is proposed. Disciplines Condensed Matter Physics | Materials Science and Engineering | Metallurgy Comments

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“…16,17 On the Co-rich side, the ferromagnetically ordered Co ions have a strong polarization effect on the AFM order of Ce moments. 14,18 On the other hand, in the Gd(Fe,Co)AsO series, which correspond to the case of a large 4f -magnetic moment, Fe/Co substitution also leads to a superconducting dome near the 3d-electron magnetic instability.…”

Section: Introductionmentioning

confidence: 99%