Superconductivity pairing mechanism from cobalt impurity doping in FeSe: Spin (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>s</mml:mi><mml:mo>±</mml:mo></mml:msub></mml:math>) or orbital (<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mi>s</mml:mi><mml:mrow><mml:mo>+</mml:mo><mml:mo>+</mml:mo></mml:mrow></mml:msub></mml:math>) fluctuation

Urata, Takahiro; Tanabe, Yoichi; Huynh, Khuong Kim; Yamakawa, Youichi; Kontani, Hiroshi; Tanigaki, Katsumi

doi:10.1103/physrevb.93.014507

Cited by 30 publications

(53 citation statements)

References 51 publications

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“…with α ~ 0.052 and T min ~ 4.8 K. Moreover, we also collect other three sets of T c and T sn given by either the onset temperature of MR or the cusp temperature of the in-plane magnetic magnetization on FeSe single crystal samples of the (001) orientation [25,30,31]. All the collected T c and T sn well satisfy this linear relationship as well.…”

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confidence: 72%

Observation of Ising spin-nematic order and its close relationship to the superconductivity in FeSe single crystals

Yuan

Huang

et al. 2016

Phys. Rev. B

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Superconducting FeSe single crystals of (001) orientation are synthesized via a hydrothermal ion-release route. An Ising spin-nematic order is identified by our systematic measurements of in-plane angular-dependent magnetoresistance (AMR) and static magnetization. The turn-on temperature of anisotropic AMR signifies the Ising spin-nematic ordering temperature T sn , below which a two-fold rotational symmetry is observed in the iron plane. A downward curvature appears below T sn in the temperature dependence of static magnetization for the weak in-plane magnetic field as reported previously. Remarkably, we find a universal linear relationship between T c and T sn among various superconducting samples, indicating that the spin nematicity and the superconductivity in FeSe have a common microscopic origin.

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confidence: 72%

Observation of Ising spin-nematic order and its close relationship to the superconductivity in FeSe single crystals

Yuan

Huang

et al. 2016

Phys. Rev. B

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“…T s (T c ) is decreased (increased) by isovalent doping in Fe(Se x S 1−x ) 14,15) and Fe(Se x Te 1−x ), 16) and by applying pressure, 17) whereas T s and T c are suppressed by nonmagnetic impurity (Co) doping. 18) Toward T s , the softening of the elastic constant C 66 19) and the enhancement of Raman nematic susceptibility χ c x 2 −y 2 20) are observed. These results clearly indicate the existence of ferro-orbital fluctuation and electronic ferro-orbital order, as is recognized in other ironbased superconductors, both theoretically 8,9,12,13) and experimentally.…”

Section: Introductionmentioning

confidence: 95%

Fermi Surface, Pressure-Induced Antiferromagnetic Order, and Superconductivity in FeSe

et al. 2018

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The pressure dependence of the structural (Ts), antiferromagnetic (Tm), and superconducting (Tc) transition temperatures in FeSe is investigated on the basis of the 16-band d-p model. At ambient pressure, a shallow hole pocket disappears due to the correlation effect, as observed in the angular-resolved photoemission spectroscopy (ARPES) and quantum oscillation (QO) experiments, resulting in the suppression of the antiferromagnetic order, in contrast to the other iron pnictides. The orbital-polarization interaction between the Fe d orbital and Se p orbital is found to drive the ferro-orbital order responsible for the structural transition without accompanying the antiferromagnetic order. The pressure dependence of the Fermi surfaces is derived from the first-principles calculation and is found to well account for the opposite pressure dependences of Ts and Tm, around which the enhanced orbital and magnetic fluctuations cause the double-dome structure of the eigenvalue λ in the Eliashberg equation, as consistent with that of Tc in FeSe.

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“…A problem is that it is hard to prove whether the impurities under investigation are magnetic or not -sometimes a nominally nonmagnetic impurity may pin local magnetism of the parent material [23], and sometimes a commonlyperceived magnetic element appear to lose its local moment when embedded in the parent material [24].…”

Section: Introductionmentioning

confidence: 99%

Extensive impurity-scattering study on the pairing symmetry of monolayer FeSe films onSrTiO3

et al. 2018

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Determination of the pairing symmetry in monolayer FeSe films on SrTiO3 is a requisite for understanding the high superconducting transition temperature in this system, which has attracted intense theoretical and experimental studies but remains controversial. Here, by introducing several types of point defects in FeSe monolayer films, we conduct a systematic investigation on the impurity-induced electronic states by spatially resolved scanning tunneling spectroscopy. Ranging from surface adsorption, chemical substitution to intrinsic structural modification, these defects generate a variety of scattering strength, which renders new insights on the pairing symmetry. IntroductionInterface high temperature superconductivity in monolayer FeSe films grown on SrTiO3 substrates has appealed great interest due to its intriguing interfacial effects and highest superconducting transition temperature (Tc) among iron-based superconductors. It exhibits a characteristic double-full-gap with magnitude of Δ1 ~ 10 meV and Δ2 ~15-20 meV [1][2][3] which closes over 65 K [4,5]. Regardless of the very high transition temperature, its Fermi surface (FS) consists of only electron-like pockets centered around the Brillouin zone (BZ) corners and there are no hole pockets at the BZ center that are typical in bulk iron-based superconductors, as a result of heavy interface electron doping [4][5][6]. The absence of hole pockets at the BZ center directly challenges the previously perceived s± pairing scenario that relies on strong spin fluctuation induced by the repulsive interband interaction between the hole bands around BZ center and the electron bands around BZ corner [7,8].Determination of the pairing symmetry in monolayer FeSe on SrTiO3 is a requisite for understanding the mechanism of high temperature superconductivity. Theoretical studies have proposed various pairing symmetries for such systems with only electron pockets, such as plain s-wave pairing [9][10][11] An experimental pathway to obtain information on pairing symmetry is to study atomic-scale impurity scattering by using scanning tunneling microscopy/spectroscopy (STM/STS) [18,20,21]. It is well known in theory that only magnetic impurities are pair breakers in the plain s-wave superconductors [18], whereas if the pairing order parameter is sign-changing both magnetic and nonmagnetic impurities can induce in-gap states and suppress superconductivity [19]. By introducing surface impurities on the monolayer FeSe surface, earlier STM/STS investigations indicate that the superconductivity is locally suppressed at magnetic impurities (such as Cr and Mn) but remains stubborn at non-magnetic impurities (such as Zn, Ag and K) [20]. Combining the quasi-particle interference patterns and their response to magnetic field, the authors concluded a plain s-wave pairing symmetry in monolayer FeSe on SrTiO3[20].In contrast, recently, Zn substitutional impurities at Fe-site in Li1-xFexOH intercalated FeSe compound, i.e. (Li1-xFex)OHFe1-yZnySe, which has similar FS geometry and a Tc of 40 K...

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Superconductivity pairing mechanism from cobalt impurity doping in FeSe: Spin (s±) or orbital (s++) fluctuation

Cited by 30 publications

References 51 publications

Observation of Ising spin-nematic order and its close relationship to the superconductivity in FeSe single crystals

Observation of Ising spin-nematic order and its close relationship to the superconductivity in FeSe single crystals

Fermi Surface, Pressure-Induced Antiferromagnetic Order, and Superconductivity in FeSe

Extensive impurity-scattering study on the pairing symmetry of monolayer FeSe films onSrTiO3

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