Surface Geometric and Electronic Structures of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>BaFe</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>As</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:mo stretchy="false">(</mml:mo><mml:mn>001</mml:mn><mml:mo stretchy="false">)</mml:mo></mml:math>

Nascimento, V. B.; Li, Ang; Jayasundara, Dilushan R.; Xuan, Yi; O’Neal, Jared; Pan, S. H.; Chien, TeYu; Hu, Biao; He, Xiaobo; Li, Guorong; Sefat, Athena S.; McGuire, Michael A.; Sales, B. C.; Mandrus, David; Pan, Minghu; Zhang, Jiandi; Jin, Rongying; Plummer, E. W.

doi:10.1103/physrevlett.103.076104

Cited by 66 publications

(73 citation statements)

References 17 publications

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“…On the contrary, the STM/STS studies on the '122' family are still controversial although great efforts have been put in the studies [5][6][7][8][9][10][11][12] , with main debate focused on where and how the crystal cleaves. For example, within the BaFe 2 As 2 (Ba122) unit cell, the Fe-As layers have a mirror symmetry around the Ba layer as shown in Fig.…”

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Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe₂As₂ Superconductors

Zou

et al. 2017

Nano Lett.

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Combined scanning tunneling microscopy, spectroscopy and local barrier height (LBH) studies show that low-temperature-cleaved optimally-doped Ba(Fe 1-x Co x ) 2 As 2 crystals with x=0.06, with T c = 22 K, have complicated morphologies. Although the cleavage surface and hence the morphologies are variable, the superconducting gap maps show the same gap widths and nanometer size inhomogeneities irrelevant to the morphology. Based on the spectroscopy and LBH maps, the bright patches and dark stripes in the morphologies are identified as Ba and As dominated surface terminations, respectively. Magnetic impurities, possibly due to cobalt or Fe atoms, are believed to create local in-gap state and in addition suppress the superconducting coherence peaks. This study will clarify the confusion on the cleavage surface terminations of the Fe-based superconductors, and its relation with the electronic structures.One major difference between the iron-based superconductors (FeSC) and conventional superconductors is the necessary involvement of magnetic elements. For a long time magnetic elements had been thought to suppress the superconductivity because of the competitive nature of superconductivity and magnetism, but with the cuprates and now FeSC, there are two cases of high-temperature superconductivity that apparently are magnetic in origin [1][2][3][4] .FeSC share a common Fe 2 X 2 layer structure where X is a pnictogen (P, As) or a chalcogen (S, Se, Te). With the incorporation of intercalation layers between the Fe 2 X 2 layers, FeSC are classified into five families: '11', '111', '122', '1111' and complex structure materials 3-4 . To understand the causes of this superconductivity, the relationship between the global properties and local behavior must be understood. These local signatures include chemical defects, electronic variations, dopant distributions, and strain. The '11' and '111' families have been studied extensively using scanning tunneling microscopy and spectroscopy (STM/STS) and the results are clear due to the cleanness of the cleavage as there is unique and symmetric cleavage plane, 1 and a non-polar surface with minimal surface effect [5][6] . On the contrary, the STM/STS studies on the '122' family are still controversial although great efforts have been put in the studies [5][6][7][8][9][10][11][12] , with main debate focused on where and how the crystal cleaves. For example, within the BaFe 2 As 2 (Ba122) unit cell, the Fe-As layers have a mirror symmetry around the Ba layer as shown in Fig. 1 (a). As FeAs layer is a highly polar plane, the physical cleavage through this plane might force Ba ions to be divided to both sides of the cleavage surface to alleviate the polar nature, associated with surface reconstructing. As a result, rich morphologies or "terminations" exist on the Ba122 cleavage surface. Some groups report that the crystal cleaves at Ba plane with ½ monolayer of Ba atoms to achieve the charge neutral surface 7-10 , while others suggest As atoms terminate the surface by breaking the we...

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Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe₂As₂ Superconductors

Zou

et al. 2017

Nano Lett.

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“…In BaFe 2 As 2 , a surface relaxation that consists essentially in an elongation of the As-height at the surface has been studied in Ref. 12 . The result of such a structural surface relaxation is that the two FeAs layers of the surface unit cell are no longer equivalent, putting the surface crystal structure in the same symmetry group as the bulk of α-BaCu 2 Sb 2 -namely P4/nmm -where two inequivalent layers appear due to the inversion of Cu and Sb.…”

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Direct spectroscopic evidence for completely filled Cu3dshell inBaCu2As2andα−<

Richard

Roekeghem

et al. 2015

Phys. Rev. B

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“…There is some debate in the literature on the nature of the cleavage surface [20,21,[23][24][25][26][27]. We follow the view that this system, in order to avoid a polar surface, cleaves through the Ba layer, exposing half a Ba layer on either side of the cleave [26][27][28].…”

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Pseudogap-less high-T _c superconductivity in BaCo _x Fe _2−x As ₂

Massee¹,

Huang²,

Kaas³

et al. 2010

EPL

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Surface Geometric and Electronic Structures ofBaFe2As2(001)

Cited by 66 publications

References 17 publications

Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe₂As₂ Superconductors

Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe₂As₂ Superconductors

Direct spectroscopic evidence for completely filled Cu3dshell inBaCu2As2andα−<

Pseudogap-less high-T _c superconductivity in BaCo _x Fe _2−x As ₂

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Surface Geometric and Electronic Structures ofBaFe2As2(001)

Cited by 66 publications

References 17 publications

Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe2As2 Superconductors

Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe2As2 Superconductors

Direct spectroscopic evidence for completely filled Cu3dshell inBaCu2As2andα−<

Pseudogap-less high-T c superconductivity in BaCo x Fe 2−x As 2

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Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe₂As₂ Superconductors

Effect of Surface Morphology and Magnetic Impurities on the Electronic Structure in Cobalt-Doped BaFe₂As₂ Superconductors

Pseudogap-less high-T _c superconductivity in BaCo _x Fe _2−x As ₂