Magnetization anomalies in the superconducting state of RuSr2GdCu2O8 and the magnetic study of Sr2GdRuO6

Papageorgiou, Thomas; Herrmannsdörfer, T.; Dinnebiér, Robert E.; Mai, Timo; Ernst, Tobias; Wunschel, Markus; Braun, H. F.

doi:10.1016/s0921-4534(01)01291-6

Cited by 36 publications

(27 citation statements)

References 24 publications

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“…Measuring the volume susceptibility of a stationary Ru1212 sample in a home-made SQUID system, 15 we were led to the conclusion, that measurements in magnetometers that do not necessitate sample movement would lead to the revelation of a universal behavior in the superconducting state of Ru1212 for samples of comparable quality. New experimental and software options, not available for our previous investigations, 12,13,14,15,16 allow us in the present paper to extend this discussion and provide experimental evidence that strongly supports this point of view. Additionally, we briefly describe how the magnetic-field homogeneity in a commercial SQUID system can be improved and combined with small scan lengths to give artifact-free measurements similar to those on 2 a stationary sample.…”

Section: Introductionsupporting

confidence: 53%

“…In a series of investigations, 12,13,14,15,16 we have tried to determine the origin of the reported different behaviors in the dc magnetization measurements of Ru1212 below T c . We attributed them to artifacts arising from the movement of the sample in an inhomogeneous magnetic field during the measurement in the Superconducting Quantum Interference Device (SQUID) magnetometer.…”

Section: Introductionmentioning

confidence: 99%

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Magnetization, vortex state and specific heat in the superconducting state of RuSr2GdCu2O8

et al. 2006

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Magnetic-field changes < 0.2 Oe over the scan length in magnetometers that necessitate sample movement are enough to create artifacts in the dc magnetization measurements of the weakly ferromagnetic superconductor RuSr 2 GdCu 2 O 8 (Ru1212) below the superconducting transition temperature T c ≈ 30 K. The observed features depend on the specific magnetic-field profile in the sample chamber and this explains the variety of reported behaviors for this compound below T c . An experimental procedure that combines improvement of the magnetic-field homogeneity with very small scan lengths and leads to artifact-free measurements similar to those on a stationary sample has been developed. This procedure was used to measure the mass magnetization of Ru1212 as a function of the applied magnetic field H (-20 Oe ≤ H ≤ 20 Oe) at T < T c and discuss, in conjunction with resistance and ac susceptibility measurements, the possibility of a spontaneous vortex state (SVS) for this compound. Although the existence of a SVS can not be excluded, an alternative interpretation of the results based on the granular nature of the investigated sample is also possible. Specific-heat measurements of Sr 2 GdRuO 6 (Sr2116), the precursor for the preparation of Ru1212 and thus a possible impurity phase, show that it is unlikely that Sr2116 is responsible for the specific-heat features observed for Ru1212 at T c .

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Section: Introductionsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Magnetization, vortex state and specific heat in the superconducting state of RuSr2GdCu2O8

et al. 2006

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“…One of them was a commercial (Cryogenic Consultants Ltd. S600) rf-SQUID magnetometer which allows measurements in the temperature range 1.6 K ≤ T ≤ 300 K in magnetic fields -6 T ≤ B ≤ 6 T. Details about how we tried to handle the problem of remanent fields in the superconducting magnet for our low field measurements can be found in our previous works 25,26 . Nevertheless, since our measurements indicate that field inhomogeneities were present, the given field values should be considered as estimates.…”

Section: Methodsmentioning

confidence: 99%

“…In this figure we chose to show the volume susceptibility so that estimations of the superconducting volume of the sample can be made. For the calculation we used a value of the dencity ρ = 6.7 g/cm 3 , estimated using the lattice parameters calculated previously 25 . The susceptibility of the spherical sample was corrected for geometric demagnetization using the demagnetization factor N = 1/3.…”

mentioning

confidence: 99%

Towards universal magnetization curves in the superconducting state ofRuSr2GdCu2O
Papageorgiou
¹
,
Braun
²
,
Görlach
³

et al. 2003
Phys. Rev. B
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Whereas resistivity and ac susceptibility measurements on the magnetic (T M ∼ 130 K) superconductor (T c,onset ∼ 50 K) RuSr 2 GdCu 2 O 8 (Ru-1212Gd) reported by different research groups reveal a universal behavior in its superconducting state, this is not the case with the superconducting quantum interference device (SQUID) magnetization measurements. The reported SQUID measurements in the superconducting state of Ru-1212Gd reveal a variety of behaviors, leaving the question of bulk superconductivity for this compound open. We review several of the reported behaviors by presenting measurements done on our samples belonging to the same batch. Based on the observed sensitivity of Ru-1212Gd to magnetic field inhomogeneities when it is moved in the superconducting magnet of the SQUID magnetometer during the measurements, we suggest that the reported different behaviors can be the result of different field profiles in the superconducting magnet and not of different superconducting properties. In order to avoid the artifacts arising from moving the sample in an inhomogeneous field, we did measurements on a stationary Ru-1212Gd sample employing a home made SQUID magnetometer. The measured curves showed none of the suspicious "symptoms" present in the curves measured with a magnetometer employing sample movement (e.g. no reversal of the features observed in the superconducting state of Ru-1212Gd by a field reversal) and if verified by measurements on stationary samples by other groups a universal behavior in the superconducting state of Ru-1212Gd can be revealed by the SQUID measurements too. Our considerations support the existence of bulk superconductivity for Ru-1212Gd.

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“…[19] Initially, stoichiometric amounts of high-purity Ru, Ir, SrCO 3 , Gd 2 O 3 were ground together and reacted in air at 1250 • C for 12 h in order to obtain Sr 2 GdRu 1−x Ir x O 6 (Sr-2116) precursors. Then, CuO was added to the Sr-2116 powders and ground together extensively, followed by pelletizing and sintering at 1060 • C for 72 h in flowing O 2 .…”

Section: Methodsmentioning

confidence: 99%

Superconductivity in magnetically ordered Ru1-xIr xSr2GdCu2O8 compounds

et al. 2003

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We have performed a systematic study of the structural, transport, and magnetic properties of polycrystalline samples of the magnetic superconductors Ru1−xIrxSr2GdCu2O8; x = 0, 0.02, 0.05, 0.10, and 0.15. The samples were prepared by solid state reaction and sintered at 1060 • C for 72 h under O 2 flow. X-ray diffraction analysis shows that all samples are nearly single phase and that the lattice parameters are independent of Ir content. Transport properties measurements revealed that the Ru substitution by Ir results in a decrease of Tc,onset from ∼ 50 K (x = 0) to ∼ 30 K (x = 0.10). Further addition of Ir (x > 0.10) causes an evolution from metallic to nonmetallic behavior of ρ(T). We have also found that magnetic order develops in the undoped Ru-1212 materials near T M ∼ 130 K. This temperature decreases linearly with increasing Ir content at the rate of ∼ -1.6 K / Ir at.%, suggesting that Ir effectively substitutes Ru in the RuO planes. A subtle drop in ρ(T) is observed close to T M , probably due to the suppression of the spin-flip scattering. The magnetoresistivity measurements revealed that the temperature T c,zero , in which ρ(T) ∼ 0, decreases rapidly for low applied magnetic fields (H < 2 T), and that this drop becomes much less pronounced in higher magnetic fields (2 ≤ H ≤ 18 T). The appreciable broadening of ρ(T) curves at low magnetic fields is reminiscent of the behavior in high-T c materials showing granular behavior, as for example in Sm1.85Ce0.15CuO4−y.

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Magnetization anomalies in the superconducting state of RuSr2GdCu2O8 and the magnetic study of Sr2GdRuO6

Cited by 36 publications

References 24 publications

Magnetization, vortex state and specific heat in the superconducting state of RuSr2GdCu2O8

Magnetization, vortex state and specific heat in the superconducting state of RuSr2GdCu2O8

Towards universal magnetization curves in the superconducting state ofRuSr2GdCu2O
Papageorgiou
¹
,
Braun
²
,
Görlach
³

et al. 2003
Phys. Rev. B
Self Cite
10
2
10
0
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Superconductivity in magnetically ordered Ru1-xIr xSr2GdCu2O8 compounds

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Magnetization anomalies in the superconducting state of RuSr2GdCu2O8 and the magnetic study of Sr2GdRuO6

Cited by 36 publications

References 24 publications

Magnetization, vortex state and specific heat in the superconducting state of RuSr2GdCu2O8

Magnetization, vortex state and specific heat in the superconducting state of RuSr2GdCu2O8

Towards universal magnetization curves in the superconducting state ofRuSr2GdCu2OPapageorgiou1, Braun2, Görlach3 et al. 2003Phys. Rev. BSelf Cite102100View full textAdd to dashboardCite

Superconductivity in magnetically ordered Ru1-xIr xSr2GdCu2O8 compounds

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Towards universal magnetization curves in the superconducting state ofRuSr2GdCu2O
Papageorgiou
¹
,
Braun
²
,
Görlach
³

et al. 2003
Phys. Rev. B
Self Cite
10
2
10
0
View full text Add to dashboard Cite