ECASIA19: 18th European Conference on Applications of Surface and Interface Analysis
Oct. 1 – 2, 2018
SAW Symposium, Westin Bellevue Dresden, Dresden, Germany
|Aug. 28-30, 2018||Spin , waves & interactions 2018, Greifswald, Germany|
April 8- 11, 2018
667. WE-Heraeus-Seminar on System-oriented approach to thermoelectrics: Materials – Interfaces – Devices in Bad Honnef, Germany
March 11-16, 2018
Joint Conference of the Condensed Matter Divisions of the DPG and EPS,
Feb. 1, 2018
Workshop of the DFG Priority Programme 1458 “High Temperature Superconductivity in Iron Pnictides“, IFW Dresden
Jan. 29-31, 2018
EPSQMat 2018: International Workshop on Electron and photon spectroscopies of quantum materials: status and perspectives, IFW Dresden
|Location||IFW Dresden D2E.27|
|Topic||Universal superconducting gap inhomogeneity in cuprates revealed by nonlinear response|
After almost three decades of extraordinary scientific efforts, the cuprate high-temperature superconductors continue to pose challenging queries. One of the important open questions is the nature of superconducting pre-pairing above the macroscopic transition temperature Tc. A pivotal step toward understanding pre-paring regime would be to figure out how superconductivity emerges from the unusual normal state. Hitherto existing investigations of superconducting traces above Tc has led to controversial conclusions. The main difficulty has been to separate superconducting contributions from complex normal-state behavior. Here we employ an unconventional probe – nonlinear conductivity  – which is zero in the normal state, to avoid this problem. We find for several representative cuprates that the nonlinear conductivity vanishes exponentially above Tc and exhibits temperature-scaling characterized by a universal scale Eo, irrespective of hole doping and cuprate family . Similar behavior is observed in nonlinear torque magnetization measurements  and in linear conductivity experiments .
Standard Ginzburg-Landau theory failed to fit the observed results. Instead, to explain the data we have successfully employed a simple percolative model based on inhomogeneity of superconducting gaps. We thus show that the superconducting precursor in the cuprates is strongly affected by intrinsic, universal nanoscale inhomogeneity.
 M. Doslic, D. Pelc,& M. Pozek, Rev. Sci. Instrum. 85,073905 (2014)
 D. Pelc et al., Nature Commun. 9, 4327 (2018)
 G. Yu et al., arXiv: 1710.10957 (2017)
 P. Popcevic et al., npj Quantum Materials 3, 42 (2018)
|Invited by||Prof. Dr. Bernd Büchner, Dr. Hans-Joachim Grafe|
|Location||TU Dresden, Haeckelstr. 3 Hörsaal REC/C213, Recknagel-Bau|
|Topic||Designing organic semiconductors via model reduction |
We present a common strategy to design organic semiconducting materials based on the construction of reduced (predictive) models from (detailed) atomistic one. We will argue that, somewhat counterintuitively, by removing chemical detail from the model one can more easily perform non-trivial predictions. The topics considered in this lecture include (i) the definition of a map of all organic semiconductors for charge transport; (ii) the desirable properties of electron acceptors in organic solar cells; (iii) derivation of possible design rules for semiconducting polymers; (iv) uses and limitations of machine learning approaches for the same problems.
|Invited by||Prof. Dr. Bernd Büchner|
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