TY  - CONF
AU  - Wördenweber, Roger
AU  - Schwarzkopf, Jutta
AU  - cai, biya
AU  - Dai, Yang
AU  - Braun, Dorothea
AU  - Schubert, Jürgen
TI  - Strain Engineered Ferroelectric Oxides: A Possible Route to Improved or even Novel Applications
M1  - FZJ-2016-05291
PY  - 2016
AB  - Due to their tendency to form ionic states, oxides of the 3d transition metal are (i) highly interesting for various applications and (ii) can easily be affected by relatively simple means. Well known examples are high-temperature superconductors (Tc > 100K), superisolators ( > 1012 m), or high-k material ( > 20000). Especially the latter – i.e. ferroelectric oxides - show extremely high permittivity and piezoelectricity however only close to the phase transition To which is typically far below or above room temperature. Therefore it is of interest to shift To towards room temperature without loosing too much of the extraordinary properties of the ferroelectric oxide.In this contribution I will present a way to engineer the transition temperature, the permittivity and the conductivity of epitaxially grown oxide films via strain. Anisotropic biaxial strain (tensile or compressive) is generated in NaNbO3 and SrTiO3 films (20-100nm) via epitaxially growth on single-crystalline oxide substrates with different lattice mismatch. Generally, tensile in-plane strain leads to an increase of the ferroelectric in-plane transition temperature whereas compressive strain tends to decrease the transition temperature. Shifts of the transition temperature by several 100K can easily be obtained via this method leading to room-temperature permittivity of several 1000. The phase transition itself and the ferroelectric states of the anisotropically strained films turn out to be highly complex. First, the transition temperature depends on the direction of the applied electric field which contradicts the concept of an uniform phase transition for a given system. Second, all systems, that we examined, showed relaxor properties which are usually expected for systems consisting of a mixture of phases. Third, most ferroelectric properties strongly depend on the applied electric field. The different observations are discussed in terms of existing models. Furthermore I will sketch possible concepts and first attempts to use these systems for instance for improved sensor devices (e.g. thin films SAW sensors), data storage or even exotic novel concepts like artificial synapses.
T2  - TO-BE Spring Meeting 2016
CY  - 6 Apr 2016 - 8 Apr 2016, Warwick (United Kingdom)
Y2  - 6 Apr 2016 - 8 Apr 2016
M2  - Warwick, United Kingdom
LB  - PUB:(DE-HGF)6
UR  - https://juser.fz-juelich.de/record/819684
ER  -