High-pressure phase diagram of 
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: Disappearance of superconductivity on the verge of ferromagnetism from Nd moments

Abdel-Hafiez, M.; Mito, Masaki; Shibayama, K.; Takagi, Seishi; Ishizuka, Masanori; Vasiliev, A. N.; Krellner, C.; Mao, Ho‐kwang

doi:10.1103/physrevb.98.094504

Cited by 10 publications

(6 citation statements)

References 57 publications

(61 reference statements)

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“…We explore external pressure as a tool to tune the phonon dispersions and thus the stability of the CDW phase. Pressure is considered a very clean way to tune basic electronic and structural properties without changing the stoichiometry of a material [30,31]. Our analysis shows that the temperature dependence of the lower critical fields, H c1 ðTÞ, is inconsistent with a simple isotropic s-wave type of the order parameter but are rather in favor of the presence of an anisotropic s wave.…”

mentioning

confidence: 79%

Coexistence of Superconductivity and Charge Density Waves in Tantalum Disulfide: Experiment and Theory

et al. 2020

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The coexistence of charge density wave (CDW) and superconductivity in tantalum disulfide (2H-TaS 2) at low temperature is boosted by applying hydrostatic pressures to study both vibrational and magnetic transport properties. Around P c , we observe a superconducting dome with a maximum superconducting transition temperature T c ¼ 9.1 K. First-principles calculations of the electronic structure predict that, under ambient conditions, the undistorted structure is characterized by a phonon instability at finite momentum close to the experimental CDW wave vector. Upon compression, this instability is found to disappear, indicating the suppression of CDW order. The calculations reveal an electronic topological transition (ETT), which occurs before the suppression of the phonon instability, suggesting that the ETT alone is not directly causing the structural change in the system. The temperature dependence of the first vortex penetration field has been experimentally obtained by two independent methods. While a d wave and single-gap BCS prediction cannot describe the lower critical field H c1 data, the temperature dependence of the H c1 can be well described by a single-gap anisotropic s-wave order parameter.

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confidence: 79%

Coexistence of Superconductivity and Charge Density Waves in Tantalum Disulfide: Experiment and Theory

et al. 2020

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“…to tune the phonon dispersions and thus the stability of the CDW phase. Pressure has long been recognized as a fundamental thermodynamic variable, and it is considered a very clean way to tune basic electronic and structural properties without changing the stoichiometry of a material [30,31]. Our analysis shows that the temperature dependence of the lower critical fields, H c1 (T ), is inconsistent with a simple isotropic s-wave type of the order parameter but are rather in favor of the presence of an anisotropic s-wave.…”

mentioning

confidence: 75%

Coexistence of Superconductivity and Charge Density Wave in Tantalum Disulfide: Experiment and Theory

Kvashnin,

VanGennep,

Mito

et al. 2020

Preprint

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The coexistence of charge density wave (CDW) and superconductivity in tantalum disulfide (2H-TaS2) at ambient pressure, is boosted by applying hydrostatic pressures up to 30 GPa, thereby inducing a typical dome-shaped superconducting phase. The ambient pressure CDW ground state which begins at TCDW ∼ 76 K, with critically small Fermi surfaces, was found to be fully suppressed at Pc ∼ 8.7 GPa. Around Pc, we observe a superconducting dome with a maximum superconducting transition temperature Tc = 9.1 K. First-principles calculations of the electronic structure predict that, under ambient conditions, the undistorted structure is characterized by a phonon instability at finite momentum close to the experimental CDW wave vector. Upon compression, this instability is found to disappear, indicating the suppression of CDW order. The calculations reveal an electronic topological transition (ETT), which occurs before the suppression of the phonon instability, suggesting that the ETT alone is not directly causing the structural change in the system. The temperature dependence of the first vortex penetration field has been experimentally obtained by two independent methods and the corresponding lower critical field Hc1 was deduced. While a d wave and single-gap BCS prediction cannot describe our Hc1 experiments, the temperature dependence of the Hc1 can be well described by a single-gap anisotropic s-wave order parameter.

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“…Obviously, in the undoped NdFeAsO system, the anomaly at 142 K in resistance measurements attributed to the phase transition from tetragonal P4/nmm to orthorhombic Cmma. The second anomaly found at TN ≈ 130 K corresponds to the onset of the well-known spin-density-wave (SDW) stripe-like Fe order [18]. In the absence of an externally applied field, the doped samples show a typical cooldown resistance curve for NdFeAsO1−xFx (x = 0.1, 0.15, and 0.2) single crystals.…”

Section: Transport Propertiesmentioning

confidence: 97%

“…Using a fit to the data in the whole measurement range for negligible spin-paramagnetic effects (α = 0) and spin-orbit scattering (λ = 0) yielded µ 0 H c2 = 95 T for x = 0.2. [18].…”

Section: Transport Propertiesmentioning

confidence: 99%

Single-Crystal Growth and Small Anisotropy of the Lower Critical Field in Oxypnictides: NdFeAsO1 − xFx

Hanna

Abdel-Hafiez

2020

Crystals

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High-quality single crystals of the unconventional superconductor NdFeAsO1 − xFx were grown. We developed a new optimized flux technique to overcome the difficulties in single-crystal growth and the sample quality limitations of NdFeAsO1 − xFx. The normal state of the F-doped samples exhibits simple metallic behavior upon cooling down from room temperature, followed by a sharp superconducting transition. The values of residual resistivity ratio (RRR) is 3.2, 6.4, and 10.3 for x = 0.1, 0.15, and 0.2, respectively. Both the large RRR and the narrow superconducting transition signpost the high quality of the crystals. We have examined the in- and out-of-plane lower critical fields, and the field at which vortices penetrate the sample of NdFeAsO1 − xFx (x = 0.1). The anisotropy ratio [γHc1 (0)] increased slightly with increasing temperature from 0.8 Tc to Tc. The temperature dependence of the first vortex penetration field was obtained under the static magnetic field, H, parallel to the c- and ab- axis, and pronounced changes in the Hc1(T) curvature were observed, which are attributed to the multi-band superconductivity.

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High-pressure phase diagram of NdFeAsO0.9F0.1 : Disappearance of superconductivity on the verge of ferromagnetism from Nd moments

Cited by 10 publications

References 57 publications

Coexistence of Superconductivity and Charge Density Waves in Tantalum Disulfide: Experiment and Theory

Coexistence of Superconductivity and Charge Density Waves in Tantalum Disulfide: Experiment and Theory

Coexistence of Superconductivity and Charge Density Wave in Tantalum Disulfide: Experiment and Theory

Single-Crystal Growth and Small Anisotropy of the Lower Critical Field in Oxypnictides: NdFeAsO1 − xFx

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