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Your search keyword '"Kohlstedt H"' showing total 18 results
Start Over Author "Kohlstedt H" Journal physical review b
18 results on '"Kohlstedt H"'

17. In situ hard x-ray photoemission spectroscopy of barrier-height control at metal/PMN-PT interfaces.

Author

Kröger, E., Petraru, A., Quer, A., Soni, R., Kalläne, M., Pertsev, N. A., Kohlstedt, H., and Rossnagel, K.

Subjects
*POLARIZATION (Nuclear physics), *X-ray photoelectron spectroscopy, *FERROELECTRICITY
Abstract

Metal-ferroelectric interfaces form the basis of novel electronic devices. A key effect determining the device functionality is the bias-dependent change of the electronic energy-level alignment at the interface. Here, hard x-ray photoelectron spectroscopy (HAXPES) is used to determine the energy-level alignment at two metal-ferroelectric interfaces--Au versus SrRuO3 on the relaxor ferroelectric Pb(Mg1/3Nb2/3)0.72Ti0.28O3 (PMN-PT)--directly in situ as a function of electrical bias. The bias-dependent average shifts of the PMN-PT core levels are found to have two dominant contributions on the 0.1-1-eV energy scale: one depending on the metal electrode and the remanent electric polarization and the other correlated with electric-field-induced strain. Element-specific deviations from the average shifts are smaller than 0.1 eV and appear to be related to predicted dynamical charge variations in PMN-PT. In addition, the efficiency of ferroelectric polarization switching is shown to be reduced near the coercive field under x-ray irradiation. The results establish HAXPES as a tool for the in operando investigation of metal-ferroelectric interfaces and suggest electric-field-induced modifications of the polarization distribution as a novel way to control the barrier height at such interfaces. [ABSTRACT FROM AUTHOR]

Published
2016
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18. Phase retrapping in a φ Josephson junction: Onset of the butterfly effect.

Author

Menditto, R., Sickinger, H., Weides, M., Kohlstedt, H., Žonda, M., Novotný, T., Koelle, D., Kleiner, R., and Goldobin, E.

Subjects
*JOSEPHSON junctions, *QUASISTATIC processes, *ZERO voltage switching
Abstract

We investigate experimentally the retrapping of the phase in a φ Josephson junction upon return of the junction to the zero-voltage state. Since the Josephson energy profile U0(ψ) in φ JJ is a 2π periodic double-well potential with minima at ψ=±φmod2π, the question is at which of the two minima -φ or +φ the phase will be trapped upon return from a finite voltage state during quasistatic decrease of the bias current (tilt of the potential). By measuring the relative population of two peaks in escape histograms, we determine the probability of phase trapping in the ±φ wells for different temperatures. Our experimental results agree qualitatively with theoretical predictions. In particular, we observe an onset of the butterfly effect with an oscillating probability of trapping. Unexpectedly, this probability saturates at a value different from 50% at low temperatures. [ABSTRACT FROM AUTHOR]

Published
2016
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