The Rise of T<sub>c</sub>: A Promising Paradigm via Interfacial Mechanism

Chu, C. W.; Lv, Bing; Deng, Liangzi; Lorenz, B.; Jawdat, BenMaan I.; Gooch, Melissa; Shrestha, K.; Zhu, Xiyu; Xue, Y. Y.; Wei, Fengyan

doi:10.1088/1742-6596/449/1/012014

Cited by 7 publications

(11 citation statements)

References 37 publications

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“…It has been further suggested that the superconductivity is enhanced by the interfaces between such different phases, though it is still an open question. With the unusually high T c ≈ 49 K in (Ca,R)122, which is higher than that in all other reported compounds of Ca-R-Fe-As, the data presented above are in line with the interface superconductivity model [17,31,32]. To verify that this is a universal property for all (Ca,R)122, several (Ca,Pr)122 and (Ca, La)122 crystals were tested as exemplified in Fig.…”

Section: Defect-induced Superconductivitysupporting

confidence: 72%

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Evidence for defect-induced superconductivity up to 49 K in(Ca1−xRx)Fe2

Deng

Zhao

et al. 2016

Phys. Rev. B

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To explore the origin of the unusual non-bulk superconductivity with a T c up to 49 K reported in the rareearth-doped CaFe 2 As 2 , the chemical composition, magnetization, specific heat, resistivity, and annealing effect are systematically investigated on nominal (Ca 1-x R x )Fe 2 As 2 single crystals with different x's and R = La, Ce, Pr, and Nd. All display a doping-independent T c once superconductivity is induced, a doping-dependent low field superconducting volume fraction f, and a large magnetic anisotropy η in the superconducting state, suggesting a rather inhomogeneous superconducting state in an otherwise microscale-homogenous superconductor. The wavelength dispersive spectroscopy and specific heat show the presence of defects which are closely related to f, regardless of the R involved. The magnetism further reveals that the defects are mainly superparamagnetic clusters for R = Ce, Pr, and Nd with strong intercluster interactions, implying that defects are locally self-organized. Annealing at 500 °C, without varying the doping level x, suppresses f profoundly but not the T c . The above observations provide evidence for the crucial role of defects in the occurrence of the unusually high T c ~ 49 K in (Ca 1-x R x )Fe 2 As 2 and are consistent with the interface-enhanced superconductivity recently proposed.

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Section: Defect-induced Superconductivitysupporting

confidence: 72%

“…The f observed scales well with the defect concentration n. However, direct evidence to demonstrate that the enhanced T c is caused by the interfaces between different defect-phases, as previously suggested by us [17,31,32] is yet to be provided.…”

Section: Defect-induced Superconductivitymentioning

confidence: 71%

Evidence for defect-induced superconductivity up to 49 K in(Ca1−xRx)Fe2

Deng

Zhao

et al. 2016

Phys. Rev. B

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“…This rapid suppression of superconductivity by small fields is observed up to 0.1 T and then, the SC suppression rate is reduced as the magnetic field increases towards 9 T. Figures 2(b) and (d) present the field dependencies of ρab(T) on a semi-logarithmic scale, revealing a long tail with another SC transition for both LaCa122-A and -B. The two-step SC phase transitions can be attributed to the inhomogeneously distributed high-Tc phases that are surrounded by the low-Tc or non-SC phases [9][10][11][12]. was obtained by using three different criteria of ρ90%, ρ50%, and ρ10% of the normal-state resistivity value near the Tc for each magnetic field.…”

Section: Methodsmentioning

confidence: 97%

“…The compounds have different Tc -dopant concentration phase diagrams distinguishing between hole and electron doping, compared to high-Tc cuprates, where hole doping usually induces a higher Tc than electron doping [7,8]. The origin of the higher Tc in electron-doped Ca122 is still under debate because of their large inhomogeneity and non-bulk superconductivity [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Effects of magnetic impurities on upper critical fields in the high-T_csuperconductor La-doped CaFe₂As₂

Jung¹,

Shin²,

Jang³

et al. 2017

Supercond. Sci. Technol.

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We investigate the effects of magnetic impurities on the upper critical field (μ0Hc2) in La-doped CaFe2As2 (LaCa122) single crystals. The magnetic field dependency of the superconducting transition temperature (Tc) for LaCa122 is rapidly suppressed at low fields up to ~1 kOe despite its large μ0Hc2(0) value on the order of tens of Tesla, resulting in a large positive curvature of μ0Hc2(T) near Tc. The magnetization hysteresis (M − H) loop at temperatures above Tc shows a ferromagnetic signal and the M(H) value rapidly increases with increasing magnetic field up to ~1 kOe. Taken together with the linear suppression of Tc with the magnetization in the normal state, these results suggest that the large upward curvature of μ0Hc2(T) near Tc in La-doped CaFe2As2 mainly originates from the suppression of superconductivity due to the presence of magnetic impurities.

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“…Interface--enhanced--T c s have been reported [8] in past decades in various artificially made heterostructural layered samples of different materials that are either not superconducting or superconducting with lower T c s by themselves in their equilibrium stoichiometric state at ambient. Unfortunately, questions remain as to the effects of local stress and local doping [9]. Indirect evidence has also been suggested for the unusually high T c in naturally occurring single crystals [10--12].…”

mentioning

confidence: 99%

Meissner and mesoscopic superconducting states in 1–4 unit-cell FeSe films

Deng

et al. 2014

Phys. Rev. B

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Recent reports [1,2,3] of interface--induced superconductivity in the unit--cell films of FeSe on SrTiO 3 with a T c up to ~ 65±5 K, highest among the Fe--based superconductors and second only to that of the cuprates, have generated great excitement. Here we show results of the first magnetic and resistive investigation on the 1--4 unit--cell FeSe--films on SrTiO 3 . The samples display the Meissner state below ~ 20 K with a penetration field as low as 0.1 Oe due to large edge effect at 2 K, a mesoscopic superconducting state comprising patches of dimension < 1 µm up to 45~55 K and an unusual relaxation of the diamagnetic signal up to 80 K, suggesting possible superconductivity at this high temperature. The observations demonstrate the heterogeneous nature of the superconducting state in these films and offer new insights into the role of interfaces in high temperature superconductivity proposed and future superconducting electronics fabricated.

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The Rise of T_c: A Promising Paradigm via Interfacial Mechanism

Cited by 7 publications

References 37 publications

Evidence for defect-induced superconductivity up to 49 K in(Ca1−xRx)Fe2

Evidence for defect-induced superconductivity up to 49 K in(Ca1−xRx)Fe2

Effects of magnetic impurities on upper critical fields in the high-T_csuperconductor La-doped CaFe₂As₂

Meissner and mesoscopic superconducting states in 1–4 unit-cell FeSe films

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The Rise of Tc: A Promising Paradigm via Interfacial Mechanism

Cited by 7 publications

References 37 publications

Evidence for defect-induced superconductivity up to 49 K in(Ca1−xRx)Fe2

Evidence for defect-induced superconductivity up to 49 K in(Ca1−xRx)Fe2

Effects of magnetic impurities on upper critical fields in the high-Tcsuperconductor La-doped CaFe2As2

Meissner and mesoscopic superconducting states in 1–4 unit-cell FeSe films

Contact Info

Product

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The Rise of T_c: A Promising Paradigm via Interfacial Mechanism

Effects of magnetic impurities on upper critical fields in the high-T_csuperconductor La-doped CaFe₂As₂