Anisotropic superconducting properties of optimally doped<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>BaFe</mml:mtext></mml:mrow><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mrow><mml:mtext>As</mml:mtext></mml:mrow><mml:mrow><mml:mn>0.65</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mtext>P</mml:mtext><mml:mrow><mml:mn>0.35</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>)</mml:mo>

Goh, Swee K.; Nakai, Yusuke; Ishida, K.; Klintberg, Lina E.; Ihara, Yukitoshi; Kasahara, S.; Shibauchi, T.; Matsuda, Yuji; Terashima, Takahito

doi:10.1103/physrevb.82.094502

Cited by 23 publications

(19 citation statements)

References 35 publications

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“…Note that the vertical axis of the main panel is inverted. Therefore, similar to a recent high frequency study utilizing the microcoil setup [28], the resonant frequency of the TDO increases when the sample enters the superconducting state, and this sudden increase in the resonant frequency marks the onset of superconductivity. We define T c by the intersection of two lines.…”

supporting

confidence: 69%

Enhancement of the Superconducting Transition Temperature under Pressure in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27)

Goh¹,

Klintberg²,

Silver³

et al. 2011

Preprint

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We report measurements of the pressure dependence of the superconducting transition temperature Tc in single crystal samples of the rare-earth doped superconductor Ca0.73La0.27Fe2As2. We track Tc with two techniques, via in-plane resistivity measurements and with a resonant tunnel diode oscillator circuit which is sensitive to the skin depth. We show that initially Tc rises steeply with pressure, forming a superconducting dome with a maximum Tc of ∼ 44 K at 20 kbar. We discuss this observation in the context of other electron-doped iron pnictide superconductors, and conclude that the application of pressure offers an independent way to tune Tc in this system.

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supporting

confidence: 69%

Enhancement of the Superconducting Transition Temperature under Pressure in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27)

Goh¹,

Klintberg²,

Silver³

et al. 2011

Preprint

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“…The high pressure measurements were performed in a miniature Moissanite anvil cell similar to the one employed in Refs. [29][30][31][32][33][34][35]. The culet diameter of the Moissanite anvils is 0.8 mm, and the pressure achieved was determined by the ruby fluorescence spectroscopy at room temperature.…”

mentioning

confidence: 99%

Nearly isotropic superconductivity in the layered Weyl semimetal WTe2 at 98.5 kbar

et al. 2017

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Layered transition metal dichalcogenide WTe2 has recently attracted significant attention due to the discovery of an extremely large magnetoresistance, a predicted type-II Weyl semimetallic state, and the pressure-induced superconducting state. By a careful measurement of the superconducting upper critical fields as a function of the magnetic field angle at a pressure as high as 98.5 kbar, we provide the first detailed examination of the dimensionality of the superconducting condensate in WTe2. Despite the layered crystal structure, the upper critical field exhibits a negligible field anisotropy. The angular dependence of the upper critical field can be satisfactorily described by the anisotropic mass model from 2.2 K (T /Tc ∼ 0.67) to 0.03 K (T /Tc ∼ 0.01), with a practically identical anisotropy factor γ ∼ 1.7. The temperature dependence of the upper critical field, determined for both H ⊥ ab and H // ab, can be understood by a conventional orbital depairing mechanism. Comparison of the upper critical fields along the two orthogonal field directions results in the same value of γ ∼ 1.7, leading to a temperature independent anisotropy factor from near Tc to < 0.01Tc. Our findings thus identify WTe2 as a nearly isotropic superconductor, with an anisotropy factor among one of the lowest known in superconducting transition metal dichalcogenides.The discovery of an extremely large and non-saturating magnetoresistance in semimetallic WTe 2 [1] has generated considerable research efforts [2][3][4][5][6][7][8][9][10][11]. The interest is further intensified with the prediction that WTe 2 can be a type-II Weyl semimetal, in which Weyl fermions emerge at the border between electron and hole pockets [12]. The crystal structure of WTe 2 consists of weaklybonded block-layers of W-Te atoms along the c direction. The layered nature of WTe 2 has facilitated the fabrication of devices based on thin layers of WTe 2 , enabling the application of gate voltage, and hence further exploration of fundamental physical properties in a controllable manner [8,[13][14][15][16].Another powerful tool to tune the properties of WTe 2 is pressure. With the application of pressure, superconductivity has been successfully induced in the bulk WTe 2 [17,18]. Although the temperature-pressure phase diagrams reported by two groups [17,18] are quite different, some qualitative similarities can still be observed. First, the superconducting transition temperature (T c ) takes a dome-shaped pressure dependence, with a maximum onset T c between 6.5 K and 7 K. Second, the magnetoresistance is significantly suppressed when the superconducting state sets in. In the work of Pan et al.[17], superconductivity can be induced with a pressure as low as ∼25 kbar, which is close to the pressure range where a subtle structural transformation from T d phase to 1T phase was detected via powder X-ray diffraction and Raman spectroscopy [19,20]. However, these results contradict the study of Kang et al. [18], which claims that the structure * skgoh@phy.cuhk.edu.hk of WTe...

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“…Experiments show that the transition temperature is maximal when the bond-angles most closely approximate that perfect tetrahedron (θ(As-Fe-As) = 109.5 0 ) [11,12]. More recent studies show [13] that when the tetrahedra are compressed along the c-axis, the superconducting gap becomes anisotropic, and measurements also show the presence of line nodes [14].Motivated by these issues, here we develop a theory for an isolated iron-tetrahedron embedded within a conduction sea. One of our key observations, is that in addition to their spin physics, the iron-based tetrahedra develop an orbital degree of freedom associated with the degenerate e g orbitals.…”

mentioning

confidence: 99%

mentioning

confidence: 99%

Local Quantum Criticality of an Iron-Pnictide Tetrahedron

Ong

Coleman

2012

Phys. Rev. Lett.

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Motivated by the close correlation between transition temperature (T(c)) and the tetrahedral bond angle of the As-Fe-As layer observed in the iron-based superconductors, we study the interplay between spin and orbital physics of an isolated iron-arsenide tetrahedron embedded in a metallic environment. Whereas the spin-Kondo effect is suppressed to low temperatures by Hund's coupling, the orbital degrees of freedom are expected to quantum mechanically quench at high temperatures, giving rise to an overscreened, non-Fermi liquid ground state. Translated into a dense environment, this critical state may play an important role in the superconductivity of these materials.

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Anisotropic superconducting properties of optimally dopedBaFe2(As0.65P0.35)

Cited by 23 publications

References 35 publications

Enhancement of the Superconducting Transition Temperature under Pressure in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27)

Enhancement of the Superconducting Transition Temperature under Pressure in Rare-Earth Doped Ca$_{1-x}$La$_x$Fe$_2$As$_2$ (x=0.27)

Nearly isotropic superconductivity in the layered Weyl semimetal WTe2 at 98.5 kbar

Local Quantum Criticality of an Iron-Pnictide Tetrahedron

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