Kinetics of domain redistribution in SrTiO₃ under pulsed electric fields

Abstract

SrTiO 3 is a well-studied perovskite system which undergoes an antiferrodistortive phase transition at 105 K. The low-temperature tetragonal phase exhibits different domains corresponding to the orientation of the symmetry axis. The domain structure can be changed drastically by applying electric fields. Using time-resolved neutron diffraction, the kinetics of the domain redistribution has been investigated on a time scale between microseconds and seconds. It is shown that there are at least two different types of relaxation processes on different time scales which govern the transformation. These can be related to the motion of hard and easy domain walls. Moreover, it is demonstrated that at low temperatures the field induced transition into the ferroelectric phase reveals a significant hysteresis which is reflected by the distribution of tetragonal domains. This finding supports the view of the zero field socalled quantum-paraelectric or coherent-paraelectric phase consisting of polar clusters which are removed only by heating above 40 K.

Large Current Driven Domain Wall Mobility and Gate Tuning of Coercivity in Ferrimagnetic Mn4N Thin Films

“…This very large efficiency, which might be further enhanced by using thinner Mn 4 N films, requires further in-depth studies to be understood. In particular, it is possible that a strain-based mechanism adds up to the charge transfer mechanism due to the STO substrate behavior in the low-temperature tetragonal phase. − Whatever the mechanism, this value is up to now only approached in systems with much thinner magnetic layers …”

High-Repetition Rate Optical Pump–Nuclear Resonance Probe Experiments Identify Transient Molecular Vibrations after Photoexcitation of a Spin Crossover Material

“…Therefore, NIS is especially well suited to revealing the vibrational spin marker bands originating from the HS and LS states of SCO complexes . Moreover, this technique yields the iron-projected phonon density of states (pDOS), a quantity that otherwise can be measured only by inelastic neutron scattering of bulk samples under equilibrium conditions with a time resolution of hundreds of microseconds . These features motivated us to employ novel optical pump–NIS probe experiments to derive nanosecond time-resolved 57 Fe pDOS of an iron-containing molecular compound.…”

“…12 Moreover, this technique yields the iron-projected phonon density of states (pDOS), a quantity that otherwise can be measured only by inelastic neutron scattering of bulk samples under equilibrium conditions with a time resolution of hundreds of microseconds. 13 These features motivated us to employ novel optical pump−NIS probe experiments to derive nanosecond time-resolved 57 Fe pDOS of an iron-containing molecular compound. This novel technique can be applied to any optically excitable system containing the Mossbauer-active nucleus 57 Fe, e.g., powders, single crystals but also nanoparticles and thin films.…”