Observation of the anisotropic Dirac cone in the band dispersion of 112-structured iron-based superconductor Ca0.9La0.1FeAs2

Liu, Z. T.; Xing, Xiangzhuo; Li, M. Y.; Zhou, Wei; Sun, Yue; Fan, Congcong; Yang, Hao; Liu, J. S.; Yao, Qi; Li, Wen Feng; Shi, Zhixiang; Shen, Dawei; Wang, Z.

doi:10.1063/1.4960164

Cited by 22 publications

(19 citation statements)

References 36 publications

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“…Two small pockets appear around the X point derived from these cones, demonstrated by orange circles in Fig. 1(c) and supported by ARPES experiments [54][55][56]. Furthermore, including SOC opens a gap in the Dirac cones, and the As1 layers become Z 2 topologically nontrivial, leading to an intrinsic topological insulator-high T c superconductor heterostructure in CaFeAs 2 .…”

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confidence: 53%

Boundary-Obstructed Topological High- Tc Superconductivity in Iron Pnictides

Benalcazar

et al. 2020

Phys. Rev. X

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Nontrivial topology and unconventional pairing are two central guiding principles in the contemporary search for and analysis of superconducting materials and heterostructure compounds. Previously, a topological superconductor has been predominantly conceived to result from a topologically nontrivial band subject to an intrinsic or external superconducting proximity effect. Here, we propose a new class of topological superconductors that are uniquely induced by unconventional pairing. They exhibit a boundary-obstructed higher-order topological character and, depending on their dimensionality, feature unprecedently robust Majorana bound states or hinge modes protected by chiral symmetry. We predict the 112 family of iron pnictides, such as Ca 1−x La x FeAs 2 , to be highly suited material candidates for our proposal, which can be tested by edge spectroscopy. Because of the boundary obstruction, the topologically nontrivial feature of the 112 pnictides does not reveal itself for a bulk-only torus band analysis without boundaries, and as such, it had evaded previous investigations. Our proposal not only opens a new arena for highly stable Majorana modes in high-temperature superconductors but also provides the smoking gun for extended s-wave order in the iron pnictides.

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confidence: 53%

Boundary-Obstructed Topological High- Tc Superconductivity in Iron Pnictides

Benalcazar

et al. 2020

Phys. Rev. X

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“…In contrast, for H //ab, closed loops cannot be easily formed because the cross-sectional area of the Fermi surface is almost fully open with negligible orbital effect, thus, the spin paramagnetic effect is a more dominant factor in μ 0 H c 2 ,ab ( T )1017. This scenario seems also to be suitable for this 112-type IBSs since all Fermi-surfaces exhibit two-dimensional character except for the α band345. Here, we try to give another possible scenario relevant to the spin-locked superconductivity, which has been proposed in quasi-one-dimensional superconductor K 2 Cr 3 As 3 44.…”

Section: Discussionmentioning

confidence: 99%

“…It crystallizes in a monoclinic crystal structure with a space group of P 21 , consisting of alternating stacking of FeAs and As zigzag bond layers. The FeAs layers have been proven to be responsible for the High- T c superconductivity, while the unique As zigzag bond layers could generate anisotropic Dirac cones, and an additional three-dimensional (3 D) hole pocket which is absent in other IBSs345, and may also be possible for realizing the Majorana related physics6. However, so far the pair mechanism and many basic physical properties both in the superconducting and normal states are still not well understood in this compound.…”

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confidence: 99%

Two-band and pauli-limiting effects on the upper critical field of 112-type iron pnictide superconductors

Xing

Zhou

Wang

et al. 2017

Sci Rep

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The temperature dependence of upper critical field μ0Hc2 of Ca0.83La0.17FeAs2 and Ca0.8La0.2Fe0.98Co0.02As2 single crystals are investigated by measuring the resistivity for the inter-plane (H//c) and in-plane (H//ab) directions in magnetic fields up to 60 T. It is found that μ0Hc2(T) of both crystals for H//c presents a sublinear temperature dependence with decreasing temperature, whereas the curve of μ0Hc2(T) for H//ab has a convex curvature and gradually tends to saturate at low temperatures. μ0Hc2(T) in both crystals deviates from the conventional Werthamer-Helfand-Hohenberg (WHH) theoretical model without considering spin paramagnetic effect for H//c and H//ab directions. Detailed analyses show that the behavior of μ0Hc2(T) in 112-type Iron-based superconductors (IBSs) is similar to that of most IBSs. Two-band model is required to fully reproduce the behavior of μ0Hc2(T) for H//c, while the effect of spin paramagnetic effect is responsible for the behavior of μ0Hc2(T) for H//ab.

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“…It is structurally analogous to the 112-type superconductors AFeAs 2 (A = (Ca,La) [22] or (Ca,Pr) [23]) which can be stabilized only by the partial substitution with rareearth elements [24]. Notably, the 112-type iron pnictides bear unique properties including unusual As − valence state [25,26], metallicity in the As plane [27,28], and possible non-trivial topological state [29][30][31][32], all of which are closely related to the zigzag As chains sandwiched * ghcao@zju.edu.cn by the A-site ions [see Fig. 1(c)].…”

Section: Introductionmentioning

confidence: 99%

Magnetic and superconducting phase diagram of Eu(Fe$_{1-x}$Ni$_{x}$)As$_{2}$

Liu,

Cui

et al. 2021

Preprint

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We report the Ni-doping effect on magnetism and superconductivity (SC) in an Eu-containing 112type system Eu(Fe1−xNix)As2 (0 ≤ x ≤ 0.15) by the measurements of resistivity, magnetization, and specific heat. The undoped EuFeAs2 undergoes a spin-density-wave (SDW) transition at TSDW ∼ 105 K in the Fe sublattice and a magnetic ordering at Tm ∼ 40 K in the Eu sublattice. Complex Eu-spin magnetism is manifested by a spin-glass reentrance at TSG ∼ 15 K and an additional spin reorientation at TSR ∼ 7 K. With Ni doping, the SDW order is rapidly suppressed, and SC emerges in the Ni-doping range of 0.01 ≤ x ≤ 0.1 where a maximum of the superconducting transition temperature T max c = 17.6 K shows up at x = 0.04. On the other hand, Tm decreases very slowly, yet TSG and TSR hardly change with the Ni doping. The phase diagram has been established, which suggests a very weak coupling between SC and Eu spins. The complex Eu-spin magnetism is discussed in terms of the Ruderman-Kittel-Kasuya-Yosida interactions mediated by the conduction electrons from both layers of FeAs and As surrounding Eu 2+ ions.

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Observation of the anisotropic Dirac cone in the band dispersion of 112-structured iron-based superconductor Ca0.9La0.1FeAs2

Cited by 22 publications

References 36 publications

Boundary-Obstructed Topological High- Tc Superconductivity in Iron Pnictides

Boundary-Obstructed Topological High- Tc Superconductivity in Iron Pnictides

Two-band and pauli-limiting effects on the upper critical field of 112-type iron pnictide superconductors

Magnetic and superconducting phase diagram of Eu(Fe$_{1-x}$Ni$_{x}$)As$_{2}$

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