Pressure-induced superconductivity in LaFeAsO: The role of anionic height and magnetic ordering

Kumar, Ravhi S.; Hamlin, J. J.; Maple, M. B.; Zhang, Yi; Chen, Changfeng; Baker, Jason; Cornelius, Andrew; Zhao, Yusheng; Xiao, Yuming; Sinogeikin, Stanislav V.; Chow, Paul

doi:10.1063/1.4904954

Cited by 10 publications

(22 citation statements)

References 42 publications

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“…the PP2, vanished at low-pressure. Conversely, the PP1 could be seen up to 20 GPa ( T N1 ) and 30 GPa ( T S1 ) and was robust against pressure151617. In Fig.…”

Section: Resultsmentioning

confidence: 83%

“…This is an unexpected finding that breaks the hitherto believed guideline of approaching a regular Fe Pn 4 tetrahedron with an increase in T c . Furthermore, we demonstrate that the peculiar PP2 is rapidly suppressed by pressure, while the conventional PP1 is robust against pressure151617. We suggest that strong spin-fluctuations, originating from an orbital-selective Mott state in the PP2, is a key for enhancing the T c under pressure.…”

mentioning

confidence: 74%

“…As d La-As for x = 0.20 is close to the interspace filling limit, the pressure response of α As-Fe-As results in a greater shift at higher x . Though the hard sphere perspective is simple, it can yield important findings with regard to superconductivity, but it has not been defined in explicit detail previously in the La1111 system1725. Furthermore, as h As can be calculated as: h As = d Fe-As cos( α As-Fe-As /2), it also responds to pressure and decreases significantly in the higher x region.…”

Section: Resultsmentioning

confidence: 99%

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Pressure effect on iron-based superconductor LaFeAsO1−xHx: Peculiar response of 1111-type structure

Kobayashi

Yamaura

Iimura

et al. 2016

Sci Rep

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A systematic study of the crystal structure of a layered iron oxypnictide LaFeAsO1−xHx as a function of pressure was performed using synchrotron X-ray diffraction. This compound exhibits a unique phase diagram of two superconducting phases and two parent phases. We established that the As–Fe–As angle of the FeAs4 tetrahedron widens on the application of pressure due to the interspace between the layers being nearly infilled by the large La and As atoms. Such rarely observed behaviour in iron pnictides implies that the FeAs4 coordination deviates from the regular tetrahedron in the present systems. This breaks a widely accepted structural guide that the superconductivity favours the regular tetrahedron, albeit the superconducting transition temperature (Tc) increases from 18 K at ambient pressure to 52 K at 6 GPa for x = 0.2. In the phase diagram, the second parent phase at x ~ 0.5 is suppressed by pressure as low as ~1.5 GPa in contrast to the first parent phase at x ~ 0, which is robust against pressure. We suggest that certain spin-fluctuation from the second parent phase is strongly related to high-Tc under pressure.

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“…the PP2, vanished at low-pressure. Conversely, the PP1 could be seen up to 20 GPa ( T N1 ) and 30 GPa ( T S1 ) and was robust against pressure151617. In Fig.…”

Section: Resultsmentioning

confidence: 83%

mentioning

confidence: 74%

Section: Resultsmentioning

confidence: 99%

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Pressure effect on iron-based superconductor LaFeAsO1−xHx: Peculiar response of 1111-type structure

Kobayashi

Yamaura

Iimura

et al. 2016

Sci Rep

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“…43 The absence of a structural phase boundary appears to indicate a decoupling of T ST from T SDW , which is distinct from the case for fluorine substitution studies where the structural phase transition and SDW order remain closely coupled until the abrupt emergence of superconductivity. More comprehensive X-ray diffraction measurements on single crystals of LaFeAsO to track T ST as a function of applied pressure would be very useful and are currently being carried out.…”

Section: Discussionmentioning

confidence: 96%

Electrical resistivity of single crystals of LaFeAsO under applied pressure

et al. 2014

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Measurements of electrical resistivity under applied pressure were performed on single crystalline samples of LaFeAsO grown in a molten NaAs flux. We observe a smooth suppression of spin-density wave order under nearly hydrostatic applied pressures up to 2.6 GPa and in quasi-hydrostatic pressures up to 14.7 GPa. Similar to some of the other reports on single and polycrystalline samples of LaFeAsO, these crystals exhibit a resistivity that increases as temperature is lowered. By fitting an Arrhenius law to the the semiconducting-like temperature dependence of the electrical resistivity, we extract an energy gap that is suppressed with pressure and vanishes near 10 GPa. This is accompanied by the emergence of a metallic temperature dependence of the electrical resistivity. A similar behavior is also observed in diamond anvil cell experiments carried out to ∼ 37 GPa. Complete transitions to a bulk superconducting phase are not observed in any of the experiments.

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“…It has been reported that the optimum TC is found when the FeAs4 tetrahedron is close to the regular shape and the anionic height is close to 1.38 A˚ for iron pnictides [25]. Kumar et al [8] found the optimum TC at 1.34 Å in LaFeAsO under pressure. Furthermore, it has been reported that an iso-structural superconductivity transition with H doping in LaFeAsO with a sizeable change in the pnictogen height increases TC [6].…”

Section: Introductionmentioning

confidence: 99%

An investigation of the interrelationship between pressure and correlation in LaFeAsO under pressure

Hesani

Yazdani

2018

Physica C: Superconductivity and its Applications

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Here, we investigated the interrelationship between pressure and correlation in the LaFeAsO compound by the density functional theory method combined with the dynamical mean field theory (DFT+DMFT) method. The spectral function and the occupation number (ON) of Fe-3d orbitals at different pressures were extracted from the calculations, and the importance of the role of correlation in superconductivity in iron-based compounds was indicated. The measured ON of Fe-3d orbitals demonstrated charge transfer between them and also the crucial role of the Fe-3dxy (xy) orbital in superconductivity in these materials. A switching behavior between high and low TC through decreasing the correlation was observed in our calculations, originating from the orbital switching. This shows the significant role of the orbital degrees of freedom in iron-based superconductors.

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Pressure-induced superconductivity in LaFeAsO: The role of anionic height and magnetic ordering

Cited by 10 publications

References 42 publications

Pressure effect on iron-based superconductor LaFeAsO1−xHx: Peculiar response of 1111-type structure

Pressure effect on iron-based superconductor LaFeAsO1−xHx: Peculiar response of 1111-type structure

Electrical resistivity of single crystals of LaFeAsO under applied pressure

An investigation of the interrelationship between pressure and correlation in LaFeAsO under pressure

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