The Route to Supercurrent Transparent Ferromagnetic Barriers in

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The Route To Supercurrent Transparent Ferromagnetic Barriers In Superconducting Matrix Yurii P. Ivanov, Soltan Soltan, Joachim Albrecht, Eberhard Goering, Gisela Schütz, Zaoli Zhang, and Andrey Chuvilin ACS Nano, Just Accepted Manuscript • DOI: 10.1021/acsnano.9b00888 • Publication Date (Web): 12 Apr 2019 Downloaded from http://pubs.acs.org on April 12, 2019

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The Route To Supercurrent Transparent Ferromagnetic Barriers In Superconducting Matrix Yurii P. Ivanov†,,*, Soltan Soltan§,‖, Joachim Albrecht, Eberhard Goering§, Gisela Schütz§, Zaoli Zhang, Andrey Chuvilin‡, † Department

of Materials Science & Metallurgy, University of Cambridge, Cambridge CB3

0FS, UK. 

Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, A-8700 Leoben,

Jahnstraße 12, Austria *

School of Natural Sciences, Far Eastern Federal University, 690950, Vladivostok, Russia

§

Max-Planck-Institute for Intelligent Systems, Heisenbergstr. 3, D-70569 Stuttgart, Germany

‖

Department of Physics, Faculty of Science, Helwan University, 11792 Cairo, Egypt

 Lab

for intelligent and innovative surfaces, Aalen University - Beethovenstr. 1, D-73430

Aalen, Germany ‡

CIC nanoGUNE Consolider, Av. de Tolosa 76, 20018, San Sebastian, Spain



IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013, Bilbao, Spain

ACS Paragon Plus Environment

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*e-mail: [email protected] ABSTRACT

A ferromagnetic barrier thinner than the coherence length in high-temperature superconductors is realized in multilayers of YBa2Cu3O7-δ and La0.67Ca0.33MnO3. We used epitaxial growth of YBCO on SrTiO3 substrates by pulsed laser deposition to prepare thin superconducting films with copper oxide planes oriented at an angle to the substrate surface. Subsequent deposition of LCMO and finally second YBCO layer produces a superconductor-ferromagnet-superconductor tri-layer containing an ultra-thin ferromagnetic barrier with sophisticated geometry at which the long axis of coherence length ovoid of YBCO is pointing across the LCMO ferromagnetic layer. A detailed characterization of this structure is achieved using high-resolution electron microscopy.

KEYWORDS high temperature superconductor, epitaxial oxides, ferromagnetic oxide, SFS junction, quantum electronics

Interfaces between the half-metal ferromagnet manganite La2/3Ca1/3MnO3 (LCMO) and the hightemperature superconductor YBa2Cu3O7-δ (YBCO) is a very motivational subject because of the fundamental questions aiming to reveal relations between crystallographic and electronic structures.1-19 The understanding of the interface properties can also aid in potential applications of hybrid oxide superconductor/ferromagnet/superconductor (SFS) structures in superconducting electronics and quantum computing.20 So far, it is established that interaction between thin


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ferromagnetic and superconducting layers lead to a suppression of either superconductivity or magnetism or both.21-28 This is related to the fact, that in order to maintain superconductivity a ferromagnetic layer should be made thinner than a coherence length ζ of the superconductor,29 which for optimally doped YBCO is ζc = 0.3 nm in c-direction30-34 - a typical growth direction for SFS layers. Deposition of that thin LCMO layer is technically challenging, but what is more important - it will hardly preserve its ferromagnetic properties at this scale. Though the conditions for superconductivity and ferromagnetism seems to be mutually exclusive, the solution may be found in reorienting the growth direction of YBCO, so that a much longer coherence length in ab-plane ζab = 1.6 nm could be utilized (see Figure 1).29,35,36 Then the thickness of the ferromagnetic barrier may be made up to 2-3 unit cells, which gives a hope to preserve ferromagnetism in the layer.1 This potentially may be achieved experimentally by the epitaxial growth of YBCO/LCMO/YBCO multilayers on SrTiO3 (STO) substrate with orientation different to (100). It should also be noted, that the charge transport across the barrier as well as the magnetic properties of very thin layers can also be affected by the termination atomic plane sequence at the top and the bottom interfaces of the ferromagnetic layer due to the rearrangement of the electron orbitals in the interfacing copper oxide planes.37,38


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Figure 1. Illustration of the potential increase in LCMO layer thickness by reorienting of YBCO crystal structure relative to the interface. Yellow ovals represent a coherence length ζ of the YBCO which depends on the orientation of CuO2 planes.

The main challenge in this approach is to keep a good interface quality of epitaxial SFS grown on STO substrates oriented differently than (100). The quality of the epitaxial growth and thus the quality of layer interfaces depends on the mismatch between the lattice parameter of the substrate and the film. In the case of (100) oriented STO the mismatch to (001) YBCO is negligible and typically a very high-quality films are obtained with sharp interfaces between YBCO layers and ferromagnetic LCMO barrier.1,38,39 So far, the conditions for epitaxial growth of YBCO films with c-axis oriented in plane (as schematically shown on the right panel of Figure 1) were not found. In turn, usage of the (110) orientated STO substrate results in polycrystalline (103)/(110)YBCO films with dominant (103)-orientation.40-42 These films


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demonstrate very rough surface which was considered to be unsuitable for deposition of SFS with very thin ferromagnetic barrier. An attempt to deposit an YBCO/LCMO/YBCO tri-layer film on STO(110) was reported, without actually showing that the deposition was successful, and the transport measurements were presented, based on which the possibility to realize a supercurrent-transparent ferromagnetic layer was proposed.29 In this work we explore the possibility to grow functional SFS structures on (110) STO substrate and compare them to common ones grown on (100) STO. We use high resolution (Scanning) Transmission Electron Microscopy (S)TEM and Electron Energy Loss Spectroscopy (EELS) to characterize the influence of the STO substrate orientation on the structure of SFS at an atomic level. We provide the direct evidence of the almost perfect tri-layer structure of the proposed SFS with distinct ferromagnetic barrier layer sufficiently thin to transmit the supercurrent. RESULTS AND DISCUSSION First, we have characterized SFS grown on (100) oriented STO substrate as a reference sample. As deduced from overview STEM image and EELS map presented on the Figure 2a, c, the structure consists of smooth 20 nm YBCO layers separated by 2 nm ferromagnetic barrier layer of LCMO. HR STEM image (Figure 2b) shows that the interfaces are atomically sharp. As is seen from the HAADF image, the atomic stacking sequence at the lower interface LCMO/YBCO is similar to the upper YBCO/LCMO interface (Figure 2d), where CuO2 and CuO denote atomic planes with square-planar and linear copper-oxide networks in YBCO. The proposed detailed structure of the interfaces can be found in the Supporting Information. YBCO (100) layers also show a high concentration of YBa2Cu4O7 intergrowths, complex defects which can serve as pinning sites for superconducting vortices (the white arrows on the Figure 2b).39,43,44 Such


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complex defects are visible on the HAADF image as the stripes which are wider the standard CuO rows due to the presence of additional row of CuO. These intergrowths dominate in the structure of the top YBCO layer as clearly seen from the Figure 2b. The density of intergrowths may vary significantly with the methods used for the film growth and deposition conditions.44 It is known that in composite films the concentration of these defects is usually much higher.43,45,46 It is in agreement with our observation. The introduction of the LCMO layer in between YBCO layer could be a reason for the larger density of the intergrowths in top YBCO layer.

Figure 2. (a) BF STEM overview of the (100) oriented SFS imaged in [010] zone axis of YBCO (yellow dashed box marked the position of ferromagnetic barrier, brown dashed lines – interface with STO), EELS elemental map of the ferromagnetic barrier (red colour region is from Mn-L2,3, green one is from Ba-M4,5) is shown on insert, (b) high resolution HAADF image of YBCO layers divided by ferromagnetic barrier LCMO, (c) filtered STEM image and reconstructed stacking sequence at the bottom and top interface of (100) oriented SFS (for details see also Supporting Information).


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Thus, in the case of the (100) oriented substrate YBCO grows layer by layer in (001) direction perpendicular to the STO substrate with fast growth direction (100) in-plane and slow growth direction (001) out-of-plane of the substrate. The sample with (110) substrate orientation has a very different picture of epitaxial growth. The most favorable epitaxial mismatch for the growth on the (110) STO substrate is the {103} crystallographic orientation of YBCO which corresponds to the 45 degrees inclination of c-axis in respect to the substrate surface.47 In this case the fast and slow growth directions are both at 45 degrees to the substrate. The grains nucleate in one of four possible orientations of {103} leading to polycrystalline structure with dominating 90 degrees grain boundaries. Due to the high temperature of the substrate the heterogeneous nucleation rate is very high and resultant grain size is small. Additionally, due to the inclination of the fast growth direction relative to the substrate surface, these films typically do not grow flat, but rather develop characteristic pyramidal surface profile. Figure 3 shows the cross section of the SFS grown on (110) oriented STO substrate seen in [010] zone axis of YBCO. Two types of the domains with perpendicular orientation of c-axis are clearly seen. The lateral size of the domains is of the order of 10 nm. Since the (001) is the slow growth direction of YBCO, four adjacent domains coalesce to form squire pyramid of the height of about 10 nm. These pyramids continue to grow up forming the corrugated surface of the bottom YBCO layer. Surprisingly, LCMO barrier layer grown at these deposition conditions on top of YBCO layer uniformly covers the rough termination surface (see Figure 3) preserving epitaxial relation with the substrate. As the result of such over-growth, the LCMO barrier layer in between YBCO layers forms the triangular wave with the periodicity twice the domain size of YBCO layers - 20


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nm. This is proved by the EELS analysis which identifies the LCMO barrier layer with average thickness of ~2 nm, see Figure 3c.

Figure 3. (a) HAADF STEM overview of the (110) oriented SFS (brown dashed line – interface with STO), (b) high resolution HAADF image of YBCO layers divided by ferromagnetic barrier LCMO, (c) EELS elemental map of the ferromagnetic barrier (red colour region is from Mn-L2,3, green one is from Ba-M4,5), (d) stacking sequence at the bottom and top interface of (110) oriented SFS reconstructed from yellow dashed box on (b). [010] zone axis of YBCO.

The oxidation state of 3d transition metals can be locally determined by analyzing the intensity ratio of the white-lines of (in particular for Mn) L edge in EELS spectra.48 Supporting evidence can be obtained from the analysis of the fine structure of the O K edge at the pre-peak position, which is sensitive to the valence state of the nearest neighbor 3d transition metal ions.49 The calculation of Mn L3/L2 ratio was done by using two step function as described in.48 Figure 4a shows the typical dependence of Mn L3/L2 ratio across the ferromagnetic barrier for samples of (100) and (110) oriented SFS. Overall, L3/L2 ratio for (110) SFS is substantially higher in respect


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to (100) SFS, indicating a decreased oxidation state of Mn ions in LCMO layer for (110) SFS. This is in agreement with the observed vanishing of the pre-peak at the O K edge (marked by a star on the Fig. 4b) for (110) oriented SFS. The profile across the LCMO barrier layer of the Mn L3/L2 ratio for (100) oriented SFS is very smooth and shows a very similar value for different areas probed by EELS mapping. In contrast the profile for (110) oriented SFS shows more irregularities and larger variation of the Mn L3/L2 ratio across the layer. These differences may be attributed to substantially different interface structures in these two cases, in particular different ways how CuOx planes are connected to the interface, which determines different charge transfer across the interface.37,50 The proposed detailed structure of the interfaces can be found in the Supporting Information.

Figure 4. (a) L3/L2 ratio for the Mn edge measured across the ferromagnetic barrier layer and the (b) average spectra across that layer for (100) and (110) oriented SFS.

The remining question is: if this thin LCMO layer is still ferromagnetic? Magnetization versus temperature curves for (110) SFS sample were measured in an external field of H=100 Oe parallel to the film plane in zero-field cooled (ZFC) and field-cooled (FC) regime using a SQUID-magnetometer (see Figure 5a). ZFC curve shows a strong diamagnetic signal below T =


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30 K, which corresponds to the superconducting transition of YBCO. The inset shows a magnification of the magnetic signal at higher temperatures. It can be seen that ZFC and FC curves are separated below ~ 250 K indicating the ferromagnetic ordering of the ultra-thin LCMO layer. It is known that the Curie temperature is strongly reduced in thin LCMO layers deposited on STO substrate.51 Nevertheless, the 4-5 unit cell thick LCMO layer sandwiched in YBCO shows a Tc > 200 K. This agrees with previous works26,33 showed that a 7 u.c. thick LCMO layer in between (001)-YBCO layers exhibit TCurie = 210K.

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(b) 5. Magnetization (b) Figure versus temperature M(T) (a), and magnetic loops M(H) at T = 5 K (b (b) and T = 100 K (c) for YBCO/LCMO/YBCO on STO(110) with tLCMO = 2 nm. The external magnetic field H is aligned in-plane of the sample in all cases (a), (b), and (c).


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Figures 5 (b) and (c) show the magnetization versus an external magnetic field curves for (110)oriented YBCO/LCMO/YBCO heterostructures measured at T = 5 K and at T = 100 K. At 5 K, far below the superconducting transition of the YBCO layers shows an irreversible behavior, characteristic for high-Tc superconducting epitaxial YBCO films with strong pinning of Abrikosov vortices. This is in-line with the STEM data which indicates the high density of intergrowth defects – proposed sources for the pinning of superconducting vortices. At 100 K, above the superconducting transition of YBCO and below the Curie temperature of the LCMO layer, the hysteresis loop is typical for a ferromagnetic material. Assuming observed structural quality of the layers and interfaces, and the desired orientation of CuO2 planes to superconductor/ferromagnet interface in (110) oriented SFS, one could expect the appearance of the supercurrent across nanoscale ferromagnetic barrier in this system. Indeed, in the previous paper we reported the experimental evidence of the supercurrent transport across ferromagnetic barrier for similar (110) SFS structures.29 The effect was more pronounced in the case of patterned microscale junctions. This can be explained by the existence of the small number of randomly distributed nanosized pinholes as shown in the Supporting Information. The estimated surface area ratio of the pinholes is only about 1 %, so the effect of the pinholes on the transport measurements could be significantly reduced by micropatterning.

CONCLUSIONS In has been shown that YBCO/LCMO/YBCO SFS tri-layers can be grown on (110) STO substrate. YBCO layers in this case have multidomain structure and a rough surface. As a consequence, LCMO layer has a peculiar complex topography, yet a good uniformity in thickness and perfect interfaces both to the bottom and to the top YBCO layers. Orientation of


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CuO layers of YBCO normal to 2 nm thin LCMO layer explains the transparency of (110) oriented ferromagnetic layer for supercurrent, which was experimentally shown for this system earlier. The EELS study revealed the difference in Mn oxidation states across the LCMO barrier layer depending on the crystal growth orientation. Magnetic measurements confirmed the preservation of ferromagnetic nature of 2 nm LCMO layer buried in YBCO. The studied (110) oriented SFS is a good candidate for realising a high-Tc SFS-junction with a ferromagnetic layer thinner than the coherence length of high-Tc superconductor after optimising the geometry of the devices, in particular their sizes. METHODS For both substrate orientations a tri-layer YBCO/LCMO/YBCO structures were grown by pulsed Laser deposition (PLD). 20 nm of YBCO were deposited directly on STO substrates followed by 2 nm of LCMO and of 20 nm of YBCO top layer. All layers were deposited at 730°C substrate temperature. Full oxygenation was achieved by post-annealing of the samples at 530°C and 105 Pa of oxygen pressure for 30 min followed by slow cooling to room temperature. The crosssections for (S)TEM studies were prepared using a standard Focused Ion Beam (FIB) protocol.52 Experiments were carried out at Titan 60-300 TEM (FEI Company), equipped with a highbrightness field-emission gun (X-FEG), monochromator and image-side CS-corrector (CEOS), and operated at 300 kV. EELS experiments were performed with a post-column EEL spectrometer (Quantum GIF Gatan). The optical conditions of the microscope for STEM EELS spectrum imaging were set to obtain a probe-size of 0.14 nm, with a convergence semi-angle of 10 mrad and collection semi-angle of 12 mrad.

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Supporting Information. We provide additional information and figures on the EDX, EELS and nano-diffraction study of the (100) and (110) SFSs as well as the results of the highresolution ABF and HAADF study of the interfaces between LCMO and YBCO layers (PDF). This material is available free of charge via the Internet at http://pubs.acs.org. AUTHOR INFORMATION Corresponding Author * Correspondence and requests for materials should be addressed to Dr. Yurii P. Ivanov, email: [email protected] Author Contributions Y. I., Z. Z., S. S. and A. Ch. conceived the project, S. S., J. A., E. G., G. S. prepared the samples and performed SQUID measurements, Y. I. and A. Ch. designed and performed STEM experiments and data analysis, Y. I. and A. Ch. wrote the manuscript, Z. Z and S. S. contributed to the manuscript writing. Z.Z. supervised the project. ACKNOWLEDGMENT This work was financially supported by the Austrian Science Fund (FWF): No. P29148-N36. Y. I. acknowledge support from the grant 3.7383.2017/8.9 of Ministry of Education and Science of Russian Federation. REFERENCES


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(1) Sefrioui, Z.; Arias, D.; Pena, V.; Villegas, J. E.; Varela, M.; Prieto, P.; Len, C.; Martinez, J. L.; Santamaria, J. Ferromagnetic/Superconducting Proximity Effect in La0.7Ca0.3MnO3/YBa2Cu3O7-δ Superlattices. Phys. Rev. B 2003, 67, 214511. (2) Soltan, S.; Albrecht, J.; Habermeier, H.-U. Ferromagnetic/Superconducting Bilayer Structure: a Model System for Spin Diffusion Length Estimation. Phys. Rev. B 2004, 70, 144517. (3) Pena, V.; Sefrioui, Z.; Arias, D.; Leon, C.; Santamaria, J.; Martinez, J. L.; Velthuis, S. G. E.; Hoffmann, A. Giant Magnetoresistance in Ferromagnet/Superconductor Superlattices. Phys. Rev. Lett. 2005, 94, 057002. (4) Chakhalian, J.; Srajer, G.; Strempfer, J.; Khaliullin, G.; Cezar, J. C.; Charlton, T.; Dalgliesh, R.; Bernhard, C.; Cristiani, G.; Habermeier, H.-U.; Keimer, B. Magnetism at the Interface Between Ferromagnetic and Superconducting Oxides. Nat. Phys. 2006, 2, 244-248. (5) Driza, N.; Blanco-Canosa, S.; Bakr, M.; Soltan, S.; Khalid, M.; Mustafa, L.; Kawashima, K.; Christiani, G.; Habermeier, H.-U.; Khaliullin, G.; Ulrich, C.; Le Tacon, M.; Keimer, B. LongRange Transfer of Electron–Phonon Coupling in Oxide Superlattices. Nat. Mater. 2012, 11, 675681. (6) Visani, C.; Sefrioui, Z.; Tornos, J.; Leon, C.; Briatico, J.; Bibes, M.; Barthelemy, A.; Santamaria, J.; Villegas, J. Equal-Spin Andreev Reflection and Long-Range Coherent Transport in High-Temperature Superconductor/Half-Metallic Ferromagnet Junctions. Nat. Phys. 2012, 8, 539-543. (7) Khaydukov, Yu. N.; Ovsyannikov, G. A.; Sheyerman, A. E.; Constantinian, K. Y.; Mustafa, L.; Keller, T.; Uribe-Laverde, M. A.; Kislinskii, Yu. V.; Shadrin, A. V.; Kalaboukhov, A.; Keimer, B.; Winkler, D. Evidence for Spin-Triplet Superconducting Correlations in Metal-Oxide Heterostructures with Noncollinear Magnetization. Phys. Rev. B 2014, 90, 035130.


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(8) Eschrig, M.; Kopu, J.; Cuevas, J. C.; Schon, G. Theory of Half-Metal/Superconductor Heterostructures. Phys. Rev. Lett. 2003, 90, 137003. (9) Eschrig, M.; Lofwander, T. Triplet Supercurrents in Clean and Disordered Half-Metallic Ferromagnets. Nat. Phys. 2008, 4, 138-143. (10) Bergeret, F. S.; Volkov, A. F.; Efetov, K. B. Odd Triplet Superconductivity and Related Phenomena in Superconductor-Ferromagnet Structures. Rev. Mod. Phys. 2005, 77, 1321-1373. (11) Dybko, K.; Werner-Malento, K.; Aleshkevych, P.; Wojcik, M.; Sawicki, M.; Przyslupski, P. Possible Spin-Triplet Superconducting Phase in the La0.7Sr0.3MnO3/YBa2Cu3O7/La0.7Sr0.3MnO3 Trilayer. Phys. Rev. B 2009, 80, 144504. (12) Hu, T.; Xiao, H.; Visani, C.; Sefrioui, Z.; Santamaria, J.; Almasan, C. C. Evidence from Magnetoresistance Measurements for an Induced Triplet Superconducting State in La0.7Ca0.3MnO3/YBa2Cu3O7-δ Multilayers. Phys. Rev. B 2009, 80, 060506. (13) Alidoust, M.; Linder, J.; Rashedi, G.; Yokoyama, T.; Sudbo, A. Spin-Polarized Josephson Current in Superconductor/Ferromagnet/Superconductor Junctions with Inhomogeneous Magnetization. Phys. Rev. B 2010, 81, 014512. (14) Bergeret, F. S.; Volkov, A. F.; Efetov, K. B. Long-Range Proximity Effects in Superconductor-Ferromagnet Structures. Phys. Rev. Lett. 2001, 86, 4096-4099. (15) Buzdin, A. I. Proximity Effects in Superconductor-Ferromagnet Heterostructures. Rev. Mod. Phys. 2005, 77, 935-976. (16) Bulaevskii, L. N.; Kuzii, V. V.; Sobyanin, A. A. Superconducting System with Weak Coupling to the Current in the Ground State. JETP Lett. 1977, 25, 290-293.


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(17) Buzdin, A. I.; Bulaevskii, L. N.; Panyukov, S. V. Critical-Current Oscillations As a Function of the Exchange Field and Thickness of the Ferromagnetic Metal (F) in an S-F-S Josephson Junction. JETP Lett. 1982, 35, 178-180. (18) Ryazanov, V. V.; Oboznov, V. A.; Rusanov, A. Yu.; Veretennikov, A. V.; Golubov, A.; Aarts, J. Coupling of Two Superconductors Through a Ferromagnet: Evidence for a p Junction. Phys. Rev. Lett. 2001, 86, 2427-2430. (19) Kontos, T.; Aprili, M.; Lesueur, J.; Genet, F.; Stephanidis, B.; Boursier, R. Josephson Junction Through a Thin Ferromagnetic Layer: Negative Coupling. Phys. Rev. Lett. 2002, 89, 137007. (20) Keizer, R. S.; Goennenwein, S. T. B.; Klapwijk, T. M.; Miao, G.; Xiao, G.; Gupta, A. A Spin Triplet Supercurrent through the Half-Metallic Ferromagnet CrO2. Nature 2006, 439, 825827. (21) Robinson, J. W. A.; Witt, J. D. S.; Blamire, M. G. Controlled Injection of Spin-Triplet Supercurrents into a Strong Ferromagnet. Science 2010, 329, 59-61. (22) Khaire, T. S.; Khasawneh, M. A.; Pratt, W. P.; Birge. N. O. Observation of Spin-Triplet Superconductivity in Co-Based Josephson Junctions. Phys. Rev. Lett. 2010, 104, 137002. (23) van Zalk, M.; Brinkman, A.; Aarts, J.; Hilgenkamp, H. Interface Resistance of YBa2Cu3O7δ/La0.67S0.33MnO3

Ramp-Type Contacts. Phys. Rev. B 2010, 82, 134513.

(24) Wei, J. Y. T.; Yeh, N.-C.; Fu, C. C.; Vasquez, R. P. Tunneling Spectroscopy Study of SpinPolarized Quasiparticle Injection Effects in Cuprate/Manganite Heterostructures. J. Appl. Phys. 1999, 85, 5350-5352. (25) Soltan, S.; Albrecht, J.; Habermeier, H.-U. Spin-Polarized Quasiparticle Injection Effects in YBCO Thin Films. Solid State Commun. 2005, 135, 461-465.


16

Page 17 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(27) Albrecht, J.; Soltan, S.; Habermeier, H.-U. Magnetic Pinning of Flux Lines in Heterostructures of Cuprates and Manganites. Phys. Rev. B 2005, 72, 092502. (28) Anwar, M. S.; Czeschka, F.; Hesselberth, M.; Porcu, M.; Aarts, J. Long-Range Supercurrents through Half-Metallic Ferromagnetic CrO2. Phys. Rev. B 2010, 82, 100501. (29) Soltan, S.; Albrecht, J.; Goering, E.; Schütz, G.; Mustafa, L.; Keimer, B.; Habermeier, H.-U. Preparation of a Ferromagnetic Barrier in YBa2Cu3O7–δ Thinner Than the Coherence Length. J. Appl. Phys. 2015, 118, 223902. (30) Deutscher, G.; Muller, K. A. Origin of Superconductive Glassy State and Extrinsic Critical Currents in High-Tc Oxides. Phys. Rev. Lett. 1987, 59, 1745-1747. (31) Worthington, T. K.; Gallagher, W. J.; Dinger, T. R. Anisotropic Nature of HighTemperature Superconductivity in Single-Crystal Y1Ba2Cu307. Phys. Rev. Lett. 1987, 59, 11601163. (32) Winzer, K.; Kumm, G. Fluctuation-Enhanced Conductivity and Magnetoconductivity of High-Quality YBa2Cu3O7-δ Crystals. Phys. B 1991, 82, 317-321. (33) Linker, G.; Xi, X. X.; Meyer, O.; Li, Q.; Geerk, J. Control of Growth Direction of Epitaxial YBaCuO Thin Films on SrTiO3 Substrates. Solid State Commun. 1989, 69, 249-253. (34) Habermeier, H.-U.; Lourenco, A. A. C. S.; Friedl, B.; Kircher, J.; Kohler, J. The Growth of (110) YBaCuO Thin Films and Their Characterization by Optical Methods. Solid State Commun. 1991, 77, 683-687. (35) Mandal, S.; Bose, S. K.; Sharma, R.; Budhani, R. C.; Padhan, P.; Prellier, W. Growth of [110] La2/3Sr1/3MnO3 –YBa2Cu3O7 Heterostructures. Appl. Phys. Lett. 2006, 89, 182508.


17

ACS Nano 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 21

(36) Mustafa, L.; Driza, N.; Soltan, S.; Le Tacon, M.; Habermeier, H.-U.; Keimer, B. Structural and Electronic Properties of Epitaxial YBa2Cu3O7−δ–La0.67Ca0.33MnO3 Bilayers Grown on SrTiO3 (110) Substrates. Phys. C 2014, 505, 70-73. (37) Chien, T. Y.; Kourkoutis, L. F.; Chakhalian, J.; Gray, B.; Kareev, M.; Guisinger, N. P.; Muller, D. A.; Freeland. J. W. Visualizing Short-Range Charge Transfer at the Interfaces Between Ferromagnetic and Superconducting Oxides. Nature Commun. 2013, 4, 2336. (38) Sen, K.; Perret, E.; Alberca, A.; Uribe-Laverde, M. A.; Marozau, I.; Yazdi-Rizi, M.; Mallett, B. P. P.; Marsik, P.; Piamonteze, C.; Khaydukov, Y.; Dobeli, M.; Keller, T.; Biskup, N.; Varela, M.; Vasatko, J.; Munzar, D.; Bernhard, C. X-ray Absorption Study of the Ferromagnetic Cu Moment at the YBa2Cu3O7−δ/La0.67Ca0.33MnO3 Interface and Variation of Its Exchange Interaction with the Mn Moment. Phys. Rev. B 2016, 93, 205131. (39) Zhu, Y.; Tsai, C.-F.; Wang, H. Atomic Interface Sequence, Misfit Strain Relaxation and Intrinsic Flux-Pinning Defects in Different YBa2Cu3O7 – δ Heterogeneous Systems. Supercond. Sci. Technol. 2013, 26, 025009. (40) Krumme, J-P.; Doormann, V.; Welz, F.; Eckart, R.; Dossel, O.; Dingen, W.; Schiffmann, K. Epitaxial Y1Ba2Cu3O7 -δ Thin Films with (103)/(110)- and (100)/(010)-Orientation on NdGaO3 and SrTiO3 Substrates Grown by Ion-Beam Sputter Deposition. J. Mater. Res. 1994, 9, 30323049. (41) Di Chiara, A.; Lombardi, F.; Miletto Granozio, F.; Pepe, G.; Scotti di Uccio, U.; Tafuri, F.; Valentino, M. A New Type of Biepitaxial c-Axis Tilted YBCO Josephson Junction. J. Supercond. 1996, 9, 237-244.


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Page 19 of 21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Nano

(42) Tafuri, F.; Miletto Granozio, F.; Carillo, F.; Di Chiara, A.; Verbist K.; Van Tendeloo. G. Microstructure and Josephson Phenomenology in 45° Tilt and Twist YBa2Cu3O7-δ Artificial Grain Boundaries. Phys. Rev. B 1999, 59, 11523-11531. (43) Llordés, A.; Palau, A.; Gázquez, J.; Coll, M.; Vlad, R.; Pomar, A.; Arbiol, J.; Guzmán, R.; Ye, S.; Rouco, V.; Sandiumenge, F.; Ricart, S.; Puig, T.; Varela, M.; Chateigner, D.; Vanacken, J.; Gutiérrez, J.; Moshchalkov, V.; Deutscher, G.; Magen, C.; et al. Nanoscale Strain-Induced Pair Suppression As a Vortex-Pinning Mechanism in High-Temperature Superconductors. Nature Mater. 2012, 11, 329-336. (44) Gazquez, J.; Guzman, R.; Mishra, R.; Bartolomé, E.; Salafranca, J.; Magén, C.; Varela, M.; Coll, M.; Palau, A.; Valvidares, S. M.; Gargiani, P.; Pellegrin, E.; Herrero-Martin, J.; Pennycook, S. J.; Pantelides, S. T.; Puig, T.; Obradors, X. Emerging Diluted Ferromagnetism in High- Tc Superconductors Driven by Point Defect Clusters. Adv. Sci. 2016, 3, 1500295. (45) Zhang, H.; Gauquelin, N.; Botton, G. A.; Wei, J. Y. T. Attenuation of Superconductivity in Manganite/Cuprate Heterostructures by Epitaxially-Induced CuO Intergrowths. Appl. Phys. Lett. 2013, 103, 052606. (46) Gauquelin, N.; Zhang, H.; Zhu, G.; Wei, J. Y. T.; Botton, G. A. Atomic-Scale Identification of Novel Planar Defect Phases in Heteroepitaxial YBa2Cu3O7−δ Thin Films. AIP Adv. 2018, 8, 055022. (47) Eom, C. B.; Marshall, A. F.; Suzuki, Y.; Geballe, T. H.; Boyer, B.; Pease, R. F. W.; van Dover, R. B.; Phillips, J. M. Growth Mechanisms and Properties of 90° Grain Boundaries in YBa2Cu3O7 Thin Films. Phys. Rev. B 1992, 46, 11902-11913.


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Page 20 of 21

(48) Riedl, T.; Gemming, T.; Wetzig, K. Extraction of EELS White-Line Intensities Of Manganese Compounds: Methods, Accuracy, and Valence Sensitivity. Ultramicroscopy 2006, 106, 284-291. (49) Wang, C.; Baer, D. R.; Amonette, J. E.; Engelhard, M. H.; Antony, J.; Qiang, Y. Morphology and Electronic Structure of the Oxide Shell on the Surface of Iron Nanoparticles. J. Am. Chem. Soc. 2009, 131, 8824-8832. (50) Tra, V. T.; Huang, R.; Gao, X.; Chen, Y.-J.; Liu, Y. T.; Kuo, W. C.; Chin, Y. Y.; Lin, H. J.; Chen, J. M.; Lee, J. M.; Lee, J. F.; Shi, P. S.; Jiang, M. G.; Duan, C. G.; Juang, J. Y.; Chen, C. T.; Jeng, H. T.; He, Q.; Chuang, Y.-D.; Lin, J.-Y.; et al. The Unconventional Doping in YBa2Cu3O7-x/La0.7Ca0.3MnO3 Heterostructures by Termination Control. Appl. Phys. Lett. 2017, 110, 032402. (51) Praus, R. B.; Leibold, B.; Gross, G. M.; Habermeier, H.-U. Thickness Dependent Properties of La0.67Ca0.33MnO3 Thin Films. Appl. Surf. Sci. 1999, 138, 40-43. (52) Giannuzzi, L. A.; Stevie, F. A. A Review of Focused Ion Beam Milling Techniques for TEM Specimen Preparation. Micron 1999, 30, 197–204.

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The Route to Supercurrent Transparent Ferromagnetic Barriers in

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