Visualizing short-range charge transfer at the interfaces between ferromagnetic and superconducting oxides

Chien, TeYu; Kourkoutis, Lena F.; Chakhalian, Jak; Gray, Barbara; Kareev, M.; Guisinger, Nathan P.; Muller, David A.; Freeland, J. W.

doi:10.1038/ncomms3336

Cited by 74 publications

(81 citation statements)

References 44 publications

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“…4) provides strong validation for the assignment of these E//a XAS pre-peaks to states in the planes and subsequently for the basic description of the cuprates as doped charge transfer insulators. This agreement is notable as our EELS of the plane layer differ markedly from the EELS of Chien et al 17 on the YBCO planes in LSMO:YBCO multilayers, which show no discernable pre-peak structure and a broad peak at B532.5 eV. The reason for these significant differences between the two studies is unclear, but they may be indicative of a difference in the basic electronic structure of YBCO in an LSMO:YBCO multilayer relative to a single crystal sample.…”

Section: Atomicallysupporting

confidence: 58%

“…The reason for these significant differences between the two studies is unclear, but they may be indicative of a difference in the basic electronic structure of YBCO in an LSMO:YBCO multilayer relative to a single crystal sample. In contrast, the O K spectra of the chain layer, discussed below, demonstrate a better qualitative agreement between our work and Chien et al 17 , although the O doping of the sample in Chien et al 17 is not known. In the chain layer (Fig.…”

Section: Atomicallycontrasting

confidence: 55%

“…We demonstrate that, on doping YBCO from O 6 to O 7 , the atomically resolved data of the Cu L edge spectra in the planes remain very similar, whereas at the O K edge a lower energy peak arises corresponding to doped holes running through E F (consistent with the Zhang-Rice singlet band) and justifying the description of the cuprates as doped charge transfer insulators. Our results are contrasted with recent spatially resolved EELS measurements of YBCO:LSMO multilayers 17 , which exhibit a different O K edge energy dependence.…”

contrasting

confidence: 56%

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Atomic scale real-space mapping of holes in YBa2Cu3O6+δ

et al. 2014

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The high-temperature superconductor YBa 2 Cu 3 O 6 þ d consists of two main structural units-a bilayer of CuO 2 planes that are central to superconductivity and a CuO 2 þ d chain layer. Although the functional role of the planes and chains has long been established, most probes integrate over both, which makes it difficult to distinguish the contribution of each. Here we use electron energy loss spectroscopy to directly resolve the plane and chain contributions to the electronic structure in YBa 2 Cu 3 O 6 and YBa 2 Cu 3 O 7 . We directly probe the charge transfer of holes from the chains to the planes as a function of oxygen content, and show that the change in orbital occupation of Cu is large in the chain layer but modest in CuO 2 planes, with holes in the planes doped primarily into the O 2p states. These results provide direct insight into the local electronic structure and charge transfers in this important high-temperature superconductor.

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Section: Atomicallysupporting

confidence: 58%

Section: Atomicallycontrasting

confidence: 55%

contrasting

confidence: 56%

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Atomic scale real-space mapping of holes in YBa2Cu3O6+δ

et al. 2014

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“…However, the effect of charge transfer was not studied. Very recently, cross-sectional scanning tunneling microscopy measurements have suggested [22] that charge transfer takes place with a characteristic length scale of ∼1 nm. However, the interpretation of these measurements is unclear.…”

mentioning

confidence: 99%

Competition between Covalent Bonding and Charge Transfer at Complex-Oxide Interfaces

et al. 2014

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Here we study the electronic properties of cuprate-manganite interfaces. By means of atomic resolution electron microscopy and spectroscopy, we produce a subnanometer scale map of the transition metal oxidation state profile across the interface between the high Tc superconductor YBa 2 Cu 3 O 7−δ and the colossal magnetoresistance compound (La,Ca)MnO 3 . A net transfer of electrons from manganite to cuprate with a peculiar nonmonotonic charge profile is observed. Model calculations rationalize the profile in terms of the competition between standard charge transfer tendencies (due to band mismatch), strong chemical bonding effects across the interface, and Cu substitution into the Mn lattice, with different characteristic length scales. DOI: 10.1103/PhysRevLett.112.196802 PACS numbers: 73.20.-r, 74.20.-z, 74.78.Fk A detailed understanding of the charge transfer that occurs across semiconductor interfaces has led to the development of two-dimensional electron gases [1], as well as the integer and fractional quantum Hall effect [2][3][4]. Interfaces between transition-metal oxides (TMOs) have the potential for even richer physics, due to the presence of several competing interactions with similar characteristic energies. The competition between electrostatic effects-similar to those at work in semiconductor heterostructures-and orbital physics characteristic of TMOs can give rise to exotic electronic reconstructions and novel physical behaviors. In heterostructures of LaAlO 3 =SrTiO 3 , the observation of a metalinsulator transition at the interface of these nonmagnetic (bulk) insulators [5] along with superconductivity [6] and magnetism [7]) sparked considerable interest. However, oxide interfaces also bring along many challenges. Ionic defects such as oxygen vacancies might play an important role in determining the electronic structure [8][9][10][11][12][13]. Understanding and controlling these material-physics issues-and the effect they have on the properties-is essential to fully explore the new functionalities that these fascinating compounds might bring along [14].Ferromagnetic-superconducting interfaces of La 2=3 Ca 1=3 MnO 3 =YBa 2 Cu 3 O 7−δ (LCMO/YBCO) have attracted much attention. This system is a paradigmatic example of competition between strongly correlated systems with different ground states. It has been proposed, based on the difference between chemical potentials, that electronic charge would be transferred from the manganite to the cuprate [15,16]. This mechanism, however, does not consider the details of the interface. The interfacial electronic structure depends on other details, such as the atomic termination [17] for each material. At the LCMO/YBCO interface both a change in the orbital occupation and a net magnetic moment are induced in the cuprate [18,19]. Model calculations [20] were able to explain different experimental results regarding the competition between ferromagnetism and superconductivity [21]. However, the effect of charge transfer was not studied. Very recently, cross-se...

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“…Asymmetric space charge at the upper or lower interface of a thin film will directly favor one polarization state over the other via the built-in electric field. 10,11 The origin of the space charge can be manifold, for example, trapped charges due to the presence of ferroelectrically dead layers at the interfaces, 12,13 charge-transfer [14][15][16] dipole moments at electrically asymmetric interfaces, 17,18 or migration of charged defects inside the layer by internal or external electric fields. 1,2 As an example for interface chemistry, different imprint states occur for as-grown PbZr 0.2 Ti 0.8 O 3 (PZT) deposited on either SrRuO 3 (outward, P þ ) or La 0.7 Sr 0.3 MnO 3 (inward, P À ).…”

Section: Introductionmentioning

confidence: 99%

Interface-mediated ferroelectric patterning and Mn valency in nano-structured PbTiO3/La0.7Sr0.3MnO3

Krug

Doğanay

Nickel

et al. 2016

Journal of Applied Physics

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We employed a multitechnique approach using piezo-force response microscopy and photoemission microscopy to investigate a self-organizing polarization domain pattern in PbTiO3/La0.7Sr0.3MnO3 (PTO/LSMO) nanostructures. The polarization is correlated with the nanostructure morphology as well as with the thickness and Mn valence of the LSMO template layer. On the LSMO dots, the PTO is upwards polarized, whereas outside the nanodots, the polarization appears both strain and interface roughness dependent. The results suggest that the electronic structure and strain of the PTO/LSMO interface contribute to determining the internal bias of the ferroelectric layer.

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Visualizing short-range charge transfer at the interfaces between ferromagnetic and superconducting oxides

Cited by 74 publications

References 44 publications

Atomic scale real-space mapping of holes in YBa2Cu3O6+δ

Atomic scale real-space mapping of holes in YBa2Cu3O6+δ

Competition between Covalent Bonding and Charge Transfer at Complex-Oxide Interfaces

Interface-mediated ferroelectric patterning and Mn valency in nano-structured PbTiO3/La0.7Sr0.3MnO3

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