Tuning of the superconducting and ferromagnetic transitions by Cu doping for Ru in GdSr2RuCu2O8

Janaki, J.; Kumary, T. Geetha; Nagarajan, R.; Mary, T. A.; Valsakumar, M. C.; Sastry, V. Sankara; Hariharan, Y.; Radhakrishnan, T. S.

doi:10.1016/s0254-0584(02)00062-7

Cited by 11 publications

(18 citation statements)

References 26 publications

(31 reference statements)

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“…We point out that small structural variations following the different thermal treatments have been observed [38]. As for the cationic ordering, measurements on Ru-Gd(1212) samples where various amounts of Cu → Ru substitution have been performed show simultaneous variation of T c and T m [35,36]; moreover, x-ray powder diffraction with Rietveld analysis on annealed samples has given indication that oxygen annealing produces variation in the cationic order, and, in particular, a certain amount of Cu → Ru substitution [37]. However, a definitive assessment of these questions needs further work and in particular a stringent control on the oxygen concentration, cationic order and structural parameters in the various samples.…”

Section: Discussionmentioning

confidence: 99%

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr₂GdCu₂O₈

Cimberle

Tropeano

Ferretti

et al. 2005

Supercond. Sci. Technol.

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In this paper we analyse the structural and physical properties of rutheno-cuprate samples of the phase Ru-Gd(1212) subjected to different thermal treatments. We have observed the variations induced by these treatments by structural measurements (x-ray powder diffraction and high-resolution transmission electron microscopy) and physical measurements (dc magnetic measurements and magnetoresistive measurements).Such variations involve both the intrinsic properties of the Ru-Gd 1212 phase (for example the temperatures of the magnetic and superconducting ordering), and the extrinsic properties, i.e. those related to the microstructure of the samples, such as the domain dimension, and to their granular nature. In particular, while a prolonged annealing in flowing oxygen induces an extended microstructural homogeneity, annealing in vacuum, besides producing loss of oxygen, leads to the formation of intragranular disordered microdomains and extended planar defects. We verify how the physical properties are dependent on the level of microstructural order that determines the passage from metallic to semiconducting behaviour and, possibly, from bulk to spin glass superconducting behaviour.By saying 'bulk' superconducting behaviour we mean the behaviour commonly observed in high-T c superconductors where, as is well known, granularity is present and intergranular and intragranular properties of the sample may be observed: in appropriate experimental conditions it is possible to separate the two contributions to study the intrinsic properties of the material or to observe the character of the Josephson coupling between grains (or clusters). In contrast, the 'spin glass' is modelled as superconducting grains weakly linked into closed loops, where different supercurrent carrying states of nearly equal energy may install, producing, among other effects, metastable configurations. We suggest that the microstructure is an important cause of the different behaviour of samples otherwise very similar: strong microstructural disorder decreases the domain size inside the grains until they are comparable with the coherence length ξ (and much smaller than the penetration depth λ). In such conditions the superconducting volume of the sample becomes smaller and smaller; granularity or weak-link behaviour becomes ubiquitously present and practically determines the physical properties in the whole phase diagram.

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Section: Discussionmentioning

confidence: 99%

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr₂GdCu₂O₈

Cimberle

Tropeano

Ferretti

et al. 2005

Supercond. Sci. Technol.

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“…Each set of data was subjected to a variety of fitting protocols that included analysis in terms of Lorentzians, Gaussians and Fano lineshape, with two-point as well as multipoint baseline correction, in order to obtain a physically meaningful picture. magnetic and superconducting transitions with T c ∼ 26.5 K and T M ∼ 140 K [14]. Also shown is the structure of Gd1212 having P4/mbm structure [7].…”

Section: Methodsmentioning

confidence: 93%

“…We also address the issue of the dependence of IR modes on Cu content. This is motivated by earlier studies by one of the authors [14], wherein doping of copper at the ruthenium site was seen to systematically decrease T M , with a corresponding increase in T c with a maximum value of 47 K for a dopant concentration of ∼10%. It was of interest to see if the Cu replacement for Ru leads to any changes in the local structure and/or electronic properties that are reflected in the infrared spectrum.…”

Section: Introductionmentioning

confidence: 85%

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Temperature and composition dependence of phonon modes in GdSr₂Ru_1 xCu_2+xO₈

Sairam

Premila

Janaki

et al. 2004

J. Phys.: Condens. Matter

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Low temperature infrared absorption measurements have been carried out on GdSr 2 RuCu 2 O 8 between 300 and 10 K. With the lowering of temperature, below the magnetic transition temperature, T M , the modes corresponding to vibrations of ruthenium and planar oxygen atoms are observed to harden significantly, over and above that determined by anharmonicity, and this is attributed to the spinphonon interaction. The mode corresponding to the vibrations of the apical oxygen has an asymmetric (Fano) lineshape, and the asymmetry parameter is seen to decrease sharply below T M , and a similar behaviour is also seen for Cu-doped GdSr 2 Ru 1−x Cu 2+x O 8 (x = 0.0-0.20). This has been understood in terms of the coupling of this phonon mode with the charge carriers. A plot of the phonon linewidth with the square of the Fano asymmetry parameter shows a linear correlation, with a slope dependent on the density of carriers. This slope and the mode frequencies of the various Cu doped samples are seen to correlate with the observed non-monotonic variation of T c with Cu content with a maximum for x = 0.1.

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“…Beside this, nanoparticles prepared by ball milling for milling time 8 h and 12 h does not show any phase transition, rather a small upturn to 0.6 emu/g is observed at low temperature. The steep increase of magnetization at low temperature may correspond to the paramagnetic contribution of the Gd 3+ moments [57]. In this way, the magnetic behavior of the nanoparticles synthesized by ball milling technique is different from those of bulk materials and ultrasonically prepared nanoparticles.…”

Section: B Magnetic Propertiesmentioning

confidence: 99%

Preparation of high crystalline nanoparticles of rare-earth based complex pervoskites and comparison of their structural and magnetic properties with bulk counterparts

Basith

Islam

Ahmmad

et al. 2017

Mater. Res. Express

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A simple route to prepare Gd 0.7 Sr 0.3 MnO 3 nanoparticles by ultrasonication of their bulk powder materials is presented in this article. For comparison, Gd 0.7 Sr 0.3 MnO 3 nanoparticles are also prepared by ball milling. The prepared samples are characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX), X-ray photoelectron spectroscope (XPS), and Superconducting Quantum Interference Device (SQUID) magnetometer. XRD Rietveld analysis is carried out extensively for the determination of crystallographic parameters and the amount of crystalline and amorphous phases. FESEM images demonstrate the formation of nanoparticles with average particle size in the range of 50-100 nm for both ultrasonication and 4 hours (h) of ball milling. The bulk materials and nanoparticles synthesized by both ultrasonication and 4 h ball milling exhibit a paramagnetic to spin-glass transition. However, nanoparticles synthesized by 8 h and 12 h ball milling do not reveal any phase transition, rathershow an upturn of magnetization at low temperature. The degradation of the magnetic properties in ball milled nanoparticles may be associated with amorphization of the nanoparticles due to ball milling particularly for milling time exceeding 8 h. This investigation demonstrates the potential of ultrasonication as a simple route to prepare high crystalline rare-earth based manganite nanoparticles with improved control compared to the traditional ball milling technique.

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Tuning of the superconducting and ferromagnetic transitions by Cu doping for Ru in GdSr2RuCu2O8

Cited by 11 publications

References 26 publications

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr₂GdCu₂O₈

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr₂GdCu₂O₈

Temperature and composition dependence of phonon modes in GdSr₂Ru_1 xCu_2+xO₈

Preparation of high crystalline nanoparticles of rare-earth based complex pervoskites and comparison of their structural and magnetic properties with bulk counterparts

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Tuning of the superconducting and ferromagnetic transitions by Cu doping for Ru in GdSr2RuCu2O8

Cited by 11 publications

References 26 publications

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr2GdCu2O8

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr2GdCu2O8

Temperature and composition dependence of phonon modes in GdSr2Ru1 xCu2+xO8

Preparation of high crystalline nanoparticles of rare-earth based complex pervoskites and comparison of their structural and magnetic properties with bulk counterparts

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Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr₂GdCu₂O₈

Effect of disorder on the passage from bulk superconductivity to spin glass behaviour in RuSr₂GdCu₂O₈

Temperature and composition dependence of phonon modes in GdSr₂Ru_1 xCu_2+xO₈