Signature of magnetic-dependent gapless odd frequency states at superconductor/ferromagnet interfaces

Nature Communications

Volumn 6, Issue , 2015, Pages

  Di Bernardo, A ^a   Diesch, S ^b   Gu, Y ^a   Linder, J ^c   Divitini, G ^a   Ducati, C ^a   Scheer, E ^b   Blamire, M G ^a   Robinson, J W A ^a  

^a UNIVERSITY OF CAMBRIDGE   (United Kingdom)

^b UNIVERSITY OF KONSTANZ   (Germany)

^c NORWEGIAN UNIVERSITY OF SCIENCE AND TECHNOLOGY   (Norway)

Author keywords

[No Author keywords available]

Indexed keywords

FERROMAGNETIC MATERIAL;

ELECTRON; MAGNETIC PROPERTY; SPECTROSCOPY; STABILIZATION; SUPERCONDUCTIVITY; SYMMETRY;

ARTICLE; CONDUCTANCE; CONTROLLED STUDY; DENSITY; ELECTRIC POTENTIAL; ENERGY; FILM; MAGNETIC FIELD; OXIDATION; SCANNING TRANSMISSION ELECTRON MICROSCOPY; SCANNING TUNNELLING SPECTROSCOPY; SPECTROSCOPY; SUPERCONDUCTOR; SURFACE PROPERTY; TEMPERATURE DEPENDENCE; TRANSITION TEMPERATURE; TRANSMISSION ELECTRON MICROSCOPY; X RAY DIFFRACTION;

EID: 84940867887     PISSN: None     EISSN: 20411723     Source Type: Journal    
DOI: 10.1038/ncomms9053     Document Type: Article

References (41)

1. Giaever, I. Energy gap in superconductors measured by electron tunneling. Phys. Rev. Lett. 5, 147-150 (1961).
2. Bardeen, J., Cooper, L. & Schrieffer, J. Microscopic theory of superconductivity. Phys. Rev. 106, 162-164 (1957).
3. Bergeret, F. S., Volkov, A. F. & Efetov, K. B. Enhancement of the Josephson current by an exchange field in superconductor-ferromagnet structures. Phys. Rev. Lett. 86, 3140-3143 (2001).
4. Bergeret, F. S., Volkov, A. F. & Efetov, K. B. Odd triplet superconductivity and related phenomena in superconductor-ferromagnet structures. Rev. Mod. Phys. 77, 1321-1373 (2005).
5. Khaire, T. S., Khasawneh, M. A., Mazin, A., Pratt, W. P. & Birge, N. O. Observation of spin-triplet superconductivity in Co-based junctions. Phys. Rev. Lett. 104, 137002 (2010).
6. Robinson, J. W. A., Witt, J. D. S. & Blamire, M. G. Controlled injection of spintriplet supercurrents into a strong ferromagnet. Science 329, 59-61 (2010).
7. Klose, C. et al. Optimization of spin-triplet supercurrent in ferromagnetic Josephson junctions. Phys. Rev. Lett. 108, 127002 (2011).
8. Anwar, M. S., Veldhorst, M., Brinkman, A. & Aarts, J. Long range supercurrents in ferromagnetic CrO2 using a multilayer contact structure. Appl. Phys. Lett. 100, 052602 (2012).
9. Witt, J. D. S., Robinson, J. W. A. & Blamire, M. G. Josephson junctions incorporating a conical magnetic holmium interlayer. Phys. Rev. B 85, 184526 (2012).
10. Robinson, J. W. A., Chiodi, F., Egilmez, M., Halász, G. B. & Blamire, M. G. Supercurrent enhancement in Bloch domain walls. Sci. Rep. 2, 699 (2012).
11. Gingrich, E. C. et al. Spin-triplet supercurrent in Co/Ni multilayer Josephson junctions with perpendicular anisotropy. Phys. Rev. B 86, 224506 (2012).
12. Pal, A., Barber, Z. H., Robinson, J. W. A. & Blamire, M. G. Pure second harmonic current-phase relation in spin filter Josephson junctions. Nat. Commun. 5, 3340 (2014).
13. Leksin, P. V. et al. Evidence for triplet superconductivity in a superconductorferromagnet spin valve. Phys. Rev. Lett. 109, 057005 (2012).
14. Jara, A. A. et al. Angular dependence of superconductivity in superconductor/spin-valve heterostructures. Phys. Rev. B 89, 184502 (2014).
15. Flokstra, M. G. et al. Controlled suppression of superconductivity by the generation of polarized Cooper pairs in spin valve structures. Phys. Rev. B 91, 060501 (2015).
16. Wang, X. L. et al. Giant triplet proximity effect in superconducting pseudo spin valve with engineered anisotropy. Phys. Rev. B 89, 140508 (R) (2014).
17. Banerjee, N. et al. Evidence for spin-selectivity of triplet pairs in superconducting spin-valves. Nat. Commun. 5, 3048 (2014).
18. Singh, A., Voltan, S., Lahabi, K. & Aarts, J. Colossal proximity effect in a superconducting triplet spin valve based on the half-metallic ferromagnet CrO. Phys. Rev. X 5, 021019 (2015).
19. Robinson, J. W. A. Viewpoint: a boost for superconducting logic. Physics 8, 49 (2015).
20. Linder, J., Sudbø, A., Yokoyama, T., Grein, R. & Eschrig, M. Signature of oddfrequency pairing correlations induced by a magnetic interface. Phys. Rev. B 81, 214504 (2010).
21. Yokoyama, T., Tanaka, Y. & Golubov, A. A. Manifestation of the odd-frequency spin-triplet pairing state in diffusive ferromagnet/superconductor junctions. Phys. Rev. B 75, 134510 (2007).
22. Kontos, T., Aprili, M., Lesueur, J. & Grison, X. Inhomogeneous superconductivity induced in a ferromagnet by proximity effect. Phys. Rev. Lett. 86, 304-307 (2001).
23. SanGiorgio, P., Reymond, S., Beasley, M. R., Kwon, J. H. & Char, K. Anomalous double peak structure in superconductor/ferromagnet tunneling density of states. Phys. Rev. Lett. 100, 237002 (2008).
24. Boden, K. M., Pratt, W. P. & Birge, N. O. Proximity-induced density-of-states oscillations in a superconductor/strong-ferromagnet system. Phys. Rev. B 84, 020510 (R) (2011).
25. Kalcheim, Y., Kirzhner, T., Koren, G. & Millo, O. Long-ranged proximity effect in La2/3Ca1/3MnO3/(100)YBa2Cu3O7-d ferromagnet/superconductor bilayers: evidence for induced triplet superconductivity in the ferromagnet. Phys. Rev. B 83, 064510 (2011).
26. Kalcheim, Y., Millo, O., Egilmez, M., Robinson, J. W. A. & Blamire, M. G. Evidence for anisotropic triplet superconductor order parameter in halfmetallic ferromagnetic La0.7Ca0.3MnO3 proximity coupled to superconducting Pr1.85Ce0.15CuO4. Phys. Rev. B 85, 104504 (2012).
27. Kalcheim, Y. et al. Magnetic field dependence of the proximity-induced triplet superconductivity at ferromagnet/superconductor interfaces. Phys. Rev. B 89, 180506(R) (2014).
28. Buzdin, A. et al. Proximity effects in superconductor-ferromagnet heterostructures. Rev. Mod. Phys. 77, 935-976 (2005).
29. Eschrig, E. & Löfwander, T. Triplet supercurrents in clean and disordered half-metallic ferromagnets. Nat. Phys. 4, 138-143 (2008).
30. Gu, Y. et al. Magnetic state controllable critical temperature in epitaxial Ho/Nb bilayers. APL Mater. 2, 046103 (2014).
31. Koehler, W. C., Cable, J. W., Wilkinson, M. K. & Wollan, E. O. Magnetic structure of Ho. I. The virgin state. Phys. Rev 151, 414-424 (1966).
32. Koehler, W. C., Cable, J. W., Child, H. R., Wilkinson, M. K. & Wollan, E. O. Magnetic structure of Ho. II. The magnetization process. Phys. Rev. 158, 450-461 (1967).
33. Strandburg, D. L., Legvold, S. & Spedding, F. H. Electrical and magnetic properties of Holmium single crystals. Phys. Rev. 127, 2046-2051 (1962).
34. Stöhr, J. & Siegmann, H. Magnetism: From Fundamentals to Nanoscale Dynamics (Springer, 2006).
35. Debuschewitz, C., Münstermann, F., Kunej, V. & Scheer, E. A compact and versatile scanning tunneling microscope with high energy resolution for use in a 3He cryostat. J. Low Temp. Phys. 147, 525-535 (2007).
36. Andrianov, A. V. Helical magnetic structures in heavy rare-earth metals as probable manifestation of electronic topological transition. J. Magn. Magn. Mater. 140, 749-750 (1995).
37. Hughes, I. D. et al. Lanthanide contraction and magnetism in the heavy rare earth elements. Nature 446, 650-653 (2007).
38. Cottet, A. Spectroscopy and critical temperature of diffusive superconducting/ferromagnetic hybrid structures with spin-Active interfaces. Phys. Rev. B 76, 224505 (2007).
39. Maeno, Y. et al. Superconductivity in a layered perovskite without copper. Nature 372, 532-534 (2004).
40. Linder, J. & Robinson, J. W. A. Superconducting spintronics. Nat. Phys. 11, 307-315 (2015).
41. Wolz, M., Debuschewitz, C., Belzig, E. & Scheer, E. Evidence for attractive pair interaction in diffusive gold films deduced from studies of the superconducting proximity effect with aluminium. Phys. Rev. B 84, 104516 (2011).