Mechanisms of charge transfer and redistribution in LaAlO 3/SrTiO3 revealed by high-energy optical conductivity

Nature Communications

Volumn 5, Issue , 2014, Pages

  Asmara, T C ^a   Annadi, A ^a   Santoso, I ^a   Gogoi, P K ^a   Kotlov, A ^b   Omer, H M ^a   Motapothula, M ^a   Breese, M B H ^a   Rubhausen M ^a,c,d   Venkatesan, T ^a   Ariando, ^a   Rusydi, A ^a  

^a NATIONAL UNIVERSITY OF SINGAPORE   (Singapore)

^b DESY   (Germany)

^c UNIVERSITY OF HAMBURG   (Germany)

^d Center for Free Electron Laser Science   (Germany)

Author keywords

[No Author keywords available]

Indexed keywords

LANTHANUM; STRONTIUM;

CONDUCTIVITY; PHYSICS; POLARIZATION; SAMPLING; TWO-DIMENSIONAL MODELING;

ARTICLE; ATOMIC FORCE MICROSCOPY; CONDUCTANCE; DISASTER; ELECTRIC CONDUCTIVITY; ELECTRON; ELECTRON DIFFRACTION; ELLIPSOMETRY; ENERGY; ENERGY TRANSFER; FILM; MEASUREMENT; PHOTON; PHYSICS; POLARIZATION; SURFACE PROPERTY; THICKNESS; TOPOGRAPHY;

EID: 84898606068     PISSN: None     EISSN: 20411723     Source Type: Journal    
DOI: 10.1038/ncomms4663     Document Type: Article

References (57)

1. Hwang, H. Y. et al. Emergent phenomena at oxide interfaces. Nat. Mater. 11, 103-113 (2012).
2. Hesper, R., Tjeng, L. H., Heeres, A. & Sawatzky, G. A. Photoemission evidence of electronic stabilization of polar surfaces in K3C60. Phys. Rev. B 62, 16046-16055 (2000).
3. Siemons, W. et al. Origin of charge density at LaAlO3 on SrTiO3 heterointerfaces: Possibility of intrinsic doping. Phys. Rev. Lett. 98, 196802 (2007).
4. Salluzzo, M. et al. Orbital reconstruction and the two-dimensional electron gas at the LaAlO3/SrTiO3 interface. Phys. Rev. Lett. 102, 166804 (2009).
5. Sing, M. et al. Profiling the interface electron gas of LaAlO3/SrTiO3 heterostructures with hard X-ray photoelectron spectroscopy. Phys. Rev. Lett. 102, 176805 (2009).
6. Berner, G. et al. LaAlO3/SrTiO3 oxide heterostructures studied by resonant inelastic X-ray scattering. Phys. Rev. B 82, 241405(R) (2010).
7. Berner, G. et al. Direct k-space mapping of the electronic structure in an oxideoxide interface. Phys. Rev. Lett. 110, 247601 (2013).
8. Ohtomo, A. & Hwang, H. Y. A high-mobility electron gas at the LaAlO3/SrTiO3 heterointerface. Nature 427, 423-426 (2004). (Pubitemid 38168490)
9. Thiel, S., Hammerl, G., Schmehl, A., Schneider, C. W. & Mannhart, J. Tunable quasi-two-dimensional electron gases in oxide heterostructures. Science 313, 1942-1945 (2006). (Pubitemid 44497997)
10. Reyren, N. et al. Superconducting interfaces between insulating oxides. Science 317, 1196-1199 (2007).
11. Brinkman, A. et al. Magnetic effects at the interface between non-magnetic oxides. Nat. Mater. 6, 493-496 (2007). (Pubitemid 47143453)
12. Ariando et al. Electronic phase separation at the LaAlO3/SrTiO3 interface. Nat. Commun. 2, 188-194 (2011).
13. Li, L., Richter, C., Mannhart, J. & Ashoori, R. C. Coexistence of magnetic order and two-dimensional superconductivity at LaAlO3/SrTiO3 interfaces. Nat. Phys. 7, 762-766 (2011).
14. Bert, J. A. et al. Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface. Nat. Phys. 7, 767-771 (2011).
15. Harrison, W. A., Kraut, E. A., Waldrop, J. R. & Grant, R. W. Polar heterojunction interfaces. Phys. Rev. B 18, 4402-4410 (1978).
16. Nakagawa, N., Hwang, H. Y. & Muller, D. A. Why some interfaces cannot be sharp. Nat. Mater. 5, 204-209 (2006). (Pubitemid 43320635)
17. Popović, Z. S., Satpathy, S. & Martin, R. M. Origin of the two-dimensional electron gas carrier density at the LaAlO3 on SrTiO3 interface. Phys. Rev. Lett. 101, 256801 (2008).
18. Warusawithana, M. P. et al. LaAlO3 stoichiometry is key to electron liquid formation at LaAlO3/SrTiO3 interfaces. Nat. Commun. 4, 2351 (2013).
19. Lee, J. & Demkov, A. A. Charge origin and localization at the n-type SrTiO3/LaAlO3 interface. Phys. Rev. B 78, 193104 (2008).
20. Segal, Y., Ngai, J. H., Reiner, J. W., Walker, F. J. & Ahn, C. H. X-ray photoemission studies of the metal-insulator transition in LaAlO3/SrTiO3 structures grown by molecular beam epitaxy. Phys. Rev. B 80, 241107(R) (2009).
21. Takizawa, M., Tsuda, S., Susaki, T., Hwang, H. Y. & Fujimori, A. Electronic charges and electric potential at LaAlO3/SrTiO3 interfaces studied by core-level photoemission spectroscopy. Phys. Rev. B 84, 245124 (2011).
22. Pentcheva, R. & Pickett, W. E. Avoiding the polarization catastrophe in LaAlO3 overlayers on SrTiO3 (001) through polar distortion. Phys. Rev. Lett. 102, 107602 (2009).
23. Pentcheva, R. et al. Parallel electron-hole bilayer conductivity from electronic interface reconstruction. Phys. Rev. Lett. 104, 166804 (2010).
24. Pauli, S. A. et al. Evolution of the interfacial structure of LaAlO3 on SrTiO3. Phys. Rev. Lett. 106, 036101 (2011).
25. Saluzzo, M. et al. Structural and electronic reconstructions at the LaAlO3/SrTiO3 interface. Adv. Mater. 25, 2333-2338 (2013).
26. Rusydi, A. et al. Metal-insulator transition in manganites: changes in optical conductivity up to 22 eV. Phys. Rev. B 78, 125110 (2008).
27. Majidi, M. A., Su, H., Feng, Y. P., Rübhausen, M. & Rusydi, A. Theory of highenergy optical conductivity and the role of oxygens in manganites. Phys. Rev. B 84, 075136 (2011).
28. Santoso, I. et al. Observation of room-temperature high-energy resonant excitonic effects in graphene. Phys. Rev. B 84, 081403(R) (2011).
29. Jahoda, F. C. Fundamental absorption of barium oxide from its reflectivity spectrum. Phys. Rev. 107, 1261-1265 (1957).
30. Nilsson, P. O. & Munkby, L. Investigation of errors in the Kramers-Kronig analysis of reflectance data. Phys. Kondens. Mater. 10, 290-298 (1969).
31. Rauer, R. et al. Thickness dependent phase separation in La0.7Ca0.3MnO3 films. Appl. Phys. Lett. 81, 3777-3779 (2002).
32. Savoia, A. et al. Polar catastrophe and electronic reconstructions at the LaAlO3/SrTiO3 interface: evidence from optical second harmonic generation. Phys. Rev. B 80, 075110 (2009).
33. Born, M. & Wolf, E. Principles of Optics. Chapter 1. Cambridge University Press, 2003).
34. Fujiwara, H. Spectroscopic Ellipsometry: Principles and Applications (Wiley, 2007).
35. Basletic, M. et al. Mapping the spatial distribution of charge carriers in LaAlO3/SrTiO3 heterostructures. Nat. Mater. 7, 621-625 (2008).
36. Knizhnik, A. A. et al. First-principles calculations of the electrical properties of LaAlO3 and its interface with Si. Phys. Rev. B 72, 235329 (2005).
37. Luo, X. & Wang, B. First-principles study of the electronic and optical properties in rhombohedral LaAlO3. J. Appl. Phys. 104, 053503 (2008).
38. Cardona, M. Optical properties and band structure of SrTiO3 and BaTiO3. Phys. Rev. 140, A651-A655 (1965).
39. Van Benthem, K., Elsässer, C. & French, R. H. Bulk electronic structure of SrTiO3: experiment and theory. J. Appl. Phys. 90, 6156-6164 (2001).
40. Sponza, L., Véniard, V., Sottile, F., Giorgetti, C. & Reining, L. Role of localized electrons in electron-hole interaction: The case of SrTiO3. Phys. Rev. B 87, 235102 (2013).
41. Dubroka, A. et al. Dynamical response and confinement of the electrons at the LaAlO3/SrTiO3 interface. Phys. Rev. Lett. 104, 156807 (2010).
42. Eskes, H., Meinders, M. B. J. & Sawatzky, G. A. Anomalous transfer of spectral weight in doped strongly correlated systems. Phys. Rev. Lett. 67, 1035-1038 (1991).
43. Meinders, M. B. J., Eskes, H. & Sawatzky, G. A. Spectral-weight transfer: breakdown of low-energy-scale sum rules in correlated systems. Phys. Rev. B 48, 3916-3926 (1993).
44. Zhang, L. et al. Origin of insulating behavior of the p-type LaAlO3/SrTiO3 interface: polarization-induced asymmetric distribution of oxygen vacancies. Phys. Rev. B 82, 125412 (2010).
45. Li, Y., Phattalung, S. N., Limpijumnong, S., Kim, J. & Yu, J. Formation of oxygen vacancies and charge carriers induced in the n-type interface of a LaAlO3 overlayer on SrTiO3(001). Phys. Rev. B 84, 245307 (2011).
46. Huijben, M. et al. Electronically coupled complementary interfaces between perovskite band insulators. Nat. Mater. 5, 556-560 (2006). (Pubitemid 43993078)
47. Tebano, A., Fabbri, E., Pergolesi, D., Balestrino, G. & Traversa, E. Room-temperature giant persistent photoconductivity in SrTiO3/LaAlO3 heterostructures. ACS Nano 6, 1278-1283 (2012).
48. Dildar, I. M. et al. Non-conducting interfaces of LaAlO3/SrTiO3 produced in sputter deposition: the role of stoichiometry. Appl. Phys. Lett. 102, 121601 (2013).
49. Breckenfeld, E. et al. Effect of growth induced (non)stoichiometry on interfacial conductance in LaAlO3/SrTiO3. Phys. Rev. Lett. 110, 196804 (2013).
50. Koster, G., Kropman, B. L., Rijnders, G. J. H. M., Blank, D. H. A. & Rogalla, H. Quasi-ideal strontium titanate crystal surfaces through formation of strontium hydroxide. Appl. Phys. Lett. 73, 2920-2922 (1998). (Pubitemid 128674186)
51. Rauer, R., Neuber, G., Kunze, J., Bäckström, J. & Rübhausen, M. Temperaturedependent spectral generalized magneto-optical ellipsometry for ferromagnetic compounds. Rev. Sci. Instrum. 76, 023910 (2005).
52. Zimmerer, G. Status report on luminescence investigations with synchrotron radiation at HASYLAB. Nucl. Instrum. Methods Phys. Res. A 308, 178-186 (1991).
53. Howard, C. J., Kennedy, B. J. & Chakoumakos, B. C. Neutron powder diffraction study of rhombohedral rare-earth aluminates and the rhombohedral to cubic phase transition. J. Phys. Condens. Matter 12, 349-365 (2000).
54. Clark, S. J. et al. First principles methods using CASTEP. Z. Kristallogr. 220, 567-570 (2005). (Pubitemid 40778242)
55. Monkhorst, H. J. & Pack, J. D. Special points for Brillouin-zone integrations. Phys. Rev. B 13, 5188-5192 (1976).
56. Kresse, G. & Furthmuller, J. Efficient iterative schemes for ab initio total-energy calculations using a plane-wave basis set. Phys. Rev. B 54, 11169-11186 (1996).
57. Pfrommer, B. G., Cote, M., Louie, S. G. & Cohen, M. L. Relaxation of crystals with the quasi-Newton method. J. Comput. Phys. 131, 233-240 (1997). (Pubitemid 127341393)