Superconductivity above 130 K in the Hg–Ba–Ca–Cu–O system

Schilling, Andreas; Cantoni, Marco; Guo, Jian; Ott, H. R.

doi:10.1038/363056a0

Cited by 1,551 publications

(561 citation statements)

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“…After the successful synthesis of the onelayer compound HgBa 2 CuO 4+δ (Hg-1201) with T c =94 K [62] Schilling et al [63] reported superconductivity below 133.5 K in the three-layer system HgBa 2 Ca 2 Cu 3 O 8+δ (Hg-1223). This remarkable result was immediately confirmed by other groups [64] with onset transition temperatures of the resistivity drop as high as 140 K. Until today no other compound has been found with higher superconducting temperature than Hg-1223.…”

Section: The Increase Of T C To New Records Under Imposed Pressurementioning

confidence: 99%

High Pressure Effects on Superconductivity

Lorenz

Chu

2005

Frontiers in Superconducting Materials

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The review is devoted to a discussion of the effects of high pressure imposed on superconducting materials. Low-temperature superconductors, high-temperature superconducting cuprates, and some unconventional superconducting compounds are investigated. Experimental as well as theoretical results regarding the pressure effects on Tc and other interesting properties are summarized.Comment: To be published in: "Frontiers in Superconducting Materials", Edt. A. Narlikar, Springer Verla

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Section: The Increase Of T C To New Records Under Imposed Pressurementioning

confidence: 99%

High Pressure Effects on Superconductivity

Lorenz

Chu

2005

Frontiers in Superconducting Materials

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confidence: 99%

Superconductivity above 100 K in single-layer FeSe films on doped SrTiO3

Liu

Liu³

et al. 2014

Nature Mater

1,059

843

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Search for superconductors with a T c above the liquid nitrogen temperature (77 K) led to the discovery of a high-T c cuprate with a T c above 130 K over two decades ago 16 . Even though the value of T c is only 26 K in the first Fe-based superconductor, LaFeAsO (ref. 17) with the earlier work on superconducting oxides interfaces [3][4][5][6] , demonstrates that interface between two different materials provide not only a rich system for studying two-dimensional (2D) superconductivity, but also a potential pathway to high-T c superconductivity [7][8][9][10][11][12] .Indeed, recent angle-resolved photoemission spectroscopy (ARPES) experiments on the FeSe/STO system revealed different electronic structure from those of bulk FeSe and possible occurrence of superconductivity around 65 K (refs. 13,14). An ex situ transport measurements performed on FeSe/STO protected by multiple layers of FeTe and amorphous Si overlay revealed a zero-resistance T c of 23.5 K and an onset T c > 40 K (ref. 15). Evidently the addition of protection layers suppresses superconductivity in single-layer FeSe. In this work, we report electrical transport measurements on single-layer films of FeSe grown on Nb-doped SrTiO 3 substrate using an in situ 4-point probe (4PP) technique. We found that superconductivity could be obtained even at a temperature as high as 109 K.Single-layer films of FeSe were grown on Nb-doped SrTiO 3 (001) surface by the same method as reported previously 1 , employing extra Se flux in an MBE system equipped with STM/STS and 4PP capabilities. The growth process was monitored by reflection high-energy electron diffraction (RHEED) (Fig. 1a), which allows the precise control of film growth needed to achieve one unit-cell thickness as exactly as possible. The crystal nature of the films was confirmed by STM imaging at both large and atomic scales, as shown in Figs grown on a conducting substrate, it does mean zero resistance of the film as the film shorts the conducting substrate. However, when the 4PP detects a finite voltage, it may not necessarily mean that the sample is not superconducting. Indeed, the 4PP technique is a powerful tool for investigating superconductivity in films that cannot be taken out of a UHV system or an interface that is not accessible by surface probes.Two typical I-V curves collected at 3 K in C1423 and C1234 are shown in Figs. 2b and 2c, respectively. The data demonstrate explicitly that the film is superconducting, with the critical current (I c ) defined by the current value for which the superconducting top layer can no longer short the conducting substrate with a finite resistance. Even though interpretation of the finite voltage in the superconducting I-V curves are complicated, the essentially zero voltage seen at low currents cannot be resulted from artificial effects of the contact, since all four tips of the 4PP have Ohmic contacts with the sample individually (Supplementary Information). It is also interesting to note that the extracted I c have similar values for both measurement con...

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“…Moreover, evidence of organized patterns were reported and terms like phase separation, stripes and checkerboard patterns are concepts still heavily discussed [5][6][7]. From all high-T C superconductors, the Hg-based family [8][9][10] is one of the most promising systems due to their simple tetragonal crystalline structure and the highest superconducting transition temperatures (T C ). Although these compounds present simple structures, disorder at the Hg planes is believed to be related to the location of excess oxygen, O δ , in these planes [11,12].…”

Section: Introductionmentioning

confidence: 99%

Perturbed Angular Correlations Studies in the HgBa2CaCu2O6+δ high-TC Superconductor

Mendonça¹,

Correia²,

Haas³

et al. 2010

J Supercond Nov Magn

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The electric field gradients at 199m Hg nuclei have been measured via the perturbed angular correlation (PAC) technique, allowing a full characterization of the Hg neighborhood charge distribution at high oxygen doping on the Hg planes. The PAC technique has been applied to investigate the effect of high oxygen pressure during the measurement. Polycrystalline HgBa 2 CaCu 2 O 6+δ (Hg-1212) samples have been annealed at 152 bar pressurized oxygen. The influence of oxygen pressure during the experiment was then investigated by measuring the samples at atmospheric pressure and under 152 bar oxygen pressure.The present set of PAC experiments shows that at high oxygen concentrations there is a non-uniform oxygen distribution. Moreover, the Hg environment is not free from oxygen and the results hint to a new type of ordering.

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Superconductivity above 130 K in the Hg–Ba–Ca–Cu–O system

Cited by 1,551 publications

References 6 publications

High Pressure Effects on Superconductivity

High Pressure Effects on Superconductivity

Superconductivity above 100 K in single-layer FeSe films on doped SrTiO3

Perturbed Angular Correlations Studies in the HgBa2CaCu2O6+δ high-TC Superconductor

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