Oxygen-induced superconducting, metallic or insulating behaviour in as-grown epitaxial Bi2Sr2CuOx thin films

The in-plane magnetoresistance of an epitaxial Bi2Sr2CuO 6+δ thin film was systematically investigated as a function of doping, above Tc. The orbital magnetoconductance is used to extract the crossover field line H * c2 (T ) in the fluctuation regime. This field is found in good agreement with the upper critical field obtained from resistivity data below Tc, and exhibits a similar upward curvature, thus pointing toward the existence of a critical correlation length. The consequences regarding the nature of the resistive transition are discussed.

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“…The sample was grown on a heated SrTiO 3 substrate, using rf sputtering (Ref. 21 and refs. therein) and characterized by X-ray diffraction.…”

Section: A Sample and Experimental Setupmentioning

confidence: 99%

Upper critical field from normal state fluctuations inBi2Sr2CuO6+δ

et al. 2006

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“…The deposition conditions were similar to those previously described for pure Bi-2201 thin films. 3 To prepare films with different x values, a series of targets with the required x values were used. The composition of the films measured by RBS on films deposited on MgO is shown in table I.…”

Section: Iiexperimentalmentioning

confidence: 99%

Interplay of doping and structural modulation in superconductingBi2Sr2−xLaxCu
Li
¹
,
Raffy
²
,
Bals
³

et al. 2005
Phys. Rev. B
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We have studied the evolution of the structural modulation in epitaxial, c-axis oriented, Bi 2 Sr 2-x La x CuO 6+d thin films when varying the La content x and for a given x as a function of oxygen content. A series of thin films with 0≤x≤0.8 have been prepared in-situ by rf magnetron sputtering and characterized by R(T) measurements and RBS, TEM and X-Ray diffraction techniques. The oxygen content of each individual film was varied by thermal annealing across the phase diagram. The evolution of the structural modulation has been thoroughly studied by X-Ray diffraction in determining the variation of the amplitude of satellite reflections in special 2 axes 2θ /θ-θ scans (reciprocal space scans). It is shown that the amplitude of the modulation along the c-axis decreases strongly when x increases from 0 to 0.2. It is demonstrated that this variation is essentially governed by La content x and that changing the oxygen content by thermal treatments has a much lower influence, even suggest that the extra oxygen is the real driving force behind the modulation. In fact, the samples studied were only substituted with La in the former case and only oxygen doped in the latter. Therefore it seems clear that in order to find a possible relation between the modulation and extra oxygen, it is necessary to systematically study both doping situations.In this paper, we report our results obtained in a systematic study of both non mobile La doping (from x = 0 to x = 0.8) and mobile doping for each La content in Bi(La)-2201 thin films. The use of thin films allows us to easily modify the oxygen content of the samples and to perform transport measurements. The mobile doping levels of these thin films were varied from overdoped to underdoped. The main goal of this study is to show the relation between extra oxygen and the modulated structure for each given La content in the Bi-2201 thin films. The most important issue in the present study is that we show how much La doping influences the amplitude of the structural modulation in these thin films whatever the oxygen doping. II.EXPERIMENTALEpitaxial c-axis oriented Bi 2 Sr 2-x La x CuO 6+y (x = 0 to 0.8) thin films, 2000 to 3000 Å thick, were prepared by single target reactive rf magnetron sputtering on heated (720-750°C) single crystal SrTiO 3 (100) substrates and also on MgO (100) substrates for composition analysis. The deposition conditions were similar to those previously described for pure Bi-2201 thin films. ii) Then the samples were oxygenated in a pure oxygen flow at 420°C. iii)Finally the samples were exposed in an oxygen plasma at 420°C with 100% O 2 to obtain a still higher oxygenation level. After each treatment, the samples were characterized by the following methods. The superconducting transition temperatures of the films were measured resistively by a standard dc four-probe method and also confirmed magnetically by ac susceptibility measurement with a SQUID magnetometer. The properties of the crystal structure of the films were thoroughly studied by X-ray dif...

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“…Superconducting Sr 1-x La x CuO 2 thin films have been deposited by MBE [9] and by laser ablation [10]. Our films are deposited by a sputtering technique, that we also employ for hole-doped cuprate thin films [11].…”

Section: Introductionmentioning

confidence: 99%

Influence of oxygen reduction on the structural and electronic properties of electron-doped Sr1−xLaxCuO2 thin films

Jovanović

Raffy

et al. 2009

Physica C: Superconductivity

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Single phase, c-axis oriented, e-doped, Sr 1-x La x CuO 2 thin films were epitaxially grown on KTaO 3 and DyScO 3 substrates by reactive rf sputtering. As-grown films being insulating due to oxygen excess, oxygen reduction is necessary to observe superconductivity. Two different procedures were employed to reach superconductivity.On one hand an in-situ reduction process was conducted on a series of films deposited on both types of substrates. On the other hand, an ex-situ reduction procedure was performed sequentially on a single film deposited on DyScO 3 . The study of the influence of oxygen reduction on the structural and electronic properties of the thin films is presented and discussed.

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Oxygen-induced superconducting, metallic or insulating behaviour in as-grown epitaxial Bi2Sr2CuOx thin films

Cited by 47 publications

References 16 publications

Upper critical field from normal state fluctuations inBi2Sr2CuO6+δ

Upper critical field from normal state fluctuations inBi2Sr2CuO6+δ

Interplay of doping and structural modulation in superconductingBi2Sr2−xLaxCu
Li
¹
,
Raffy
²
,
Bals
³

et al. 2005
Phys. Rev. B
Self Cite
13
0
16
1
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Influence of oxygen reduction on the structural and electronic properties of electron-doped Sr1−xLaxCuO2 thin films

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Oxygen-induced superconducting, metallic or insulating behaviour in as-grown epitaxial Bi2Sr2CuOx thin films

Cited by 47 publications

References 16 publications

Upper critical field from normal state fluctuations inBi2Sr2CuO6+δ

Upper critical field from normal state fluctuations inBi2Sr2CuO6+δ

Interplay of doping and structural modulation in superconductingBi2Sr2−xLaxCuLi1, Raffy2, Bals3 et al. 2005Phys. Rev. BSelf Cite130161View full textAdd to dashboardCite

Influence of oxygen reduction on the structural and electronic properties of electron-doped Sr1−xLaxCuO2 thin films

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Interplay of doping and structural modulation in superconductingBi2Sr2−xLaxCu
Li
¹
,
Raffy
²
,
Bals
³

et al. 2005
Phys. Rev. B
Self Cite
13
0
16
1
View full text Add to dashboard Cite