Electric-field-induced pyroelectric order and localization of the confined electrons in LaAlO3/SrTiO3 heterostructures

Abstract

With infrared ellipsometry, x-ray diffraction, and electric transport 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 low temperature and negative gate voltage is induced, or at least strongly enhanced, by a pyroelectric phase transition in SrTiO3 which strongly reduces the lattice polarizability and the subsequent Coulomb screening. In particular, we show that the charge localisation and the polar order of SrTiO3 both develop below about 50 K and exhibit similar, unipolar hysteresis loops as a function of the gate voltage. Our findings suggest that the pyroelectric order also plays an important role in the quantum phase transition at very low temperatures where superconductivity is suppressed by an electric field.

5 pages, 4 figures, supplementary material

References in corpus (2)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Avoiding the polarization catastrophe in LaAlO3 overlayers on SrTiO3(001) through a polar distortion

Cited by in corpus (6)

• Giant Oscillating Thermopower at Oxide Interfaces
• Designing spin and orbital sources of Berry curvature at oxide interfaces
• Orbital design of Berry curvature: pinch points and giant dipoles induced by crystal fields
• Gate voltage control of the $Al{O}_x$/$SrTi{O}_3$ interface electrical properties
• Non-collinear and strongly asymmetric polar moments at back-gated SrTiO3 interfaces
• Anisotropy of the infrared-active phonon modes in the mono-domain state of tetragonal SrTiO3 (110)