Université de Fribourg

Electric-Field-Induced Polar Order and Localization of the Confined Electrons in LaAlO₃/SrTiO₃ Heterostructures

Rössle, Matthias ; Kim, Kyung Wan ; Dubroka, Adam ; Maršík, Premysl ; Wang, Chen Nan ; Jany, R. ; Richter, C. ; Mannhart, J. ; Schneider, C. W. ; Frano, A. ; Wochner, P. ; Lu, Y. ; Keimer, B. ; Shukla, D. K. ; Strempfer, J. ; Bernhard, Christian

In: Physical Review Letters, 2013, vol. 110, no. 13, p. 136805

With ellipsometry, x-ray diffraction, and resistance measurements we investigated the electric-field effect on the confined electrons at the LaAlO₃/SrTiO₃ interface. We obtained evidence that the localization of the electrons at negative gate voltage is induced, or at least enhanced, by a polar phase transition in SrTiO₃ which strongly reduces the lattice polarizability and the subsequent...

Université de Fribourg

Dimensionality control of electronic phase transitions in nickel-Oxide superlattices

Boris, A. V. ; Matiks, Y. ; Benckiser, E. ; Frano, A. ; Popovich, P. ; Hinkov, V. ; Wochner, P. ; Castro-Colin, M. ; Detemple, E. ; Malik, Vivek Kumar ; Bernhard, Christian ; Prokscha, T. ; Suter, A. ; Salman, Z. ; Morenzoni, E. ; Cristiani, G. ; Habermeier, H.-U. ; Keimer, B.

In: Science, 2011, vol. 332, no. 6032, p. 937-940

The competition between collective quantum phases in materials with strongly correlated electrons depends sensitively on the dimensionality of the electron system, which is difficult to control by standard solid-state chemistry. We have fabricated superlattices of the paramagnetic metal lanthanum nickelate (LaNiO₃) and the wide-gap insulator lanthanum aluminate (LaAlO₃) with atomically...