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September 2017

Fri., 22.

FriMat Day

Is magnetism relevant to cuprate superconductivity: lanthanides versus charge compensated 123?

Prof. Amit Keren, Physics Department, Technion, Haifa, Isreal

Time: 14:00 - 15:00h

Location: UNI-Perolles, Physics Department, building 8, auditorium 0.51, Chemin du Musee 3, 1700 Fribourg, Switzerland

Many theories suggest that the mechanism for cuprate superconductivity is based on super-exchange interaction between electrons. The most obvious test of these theories is a measurement of the correlation between Tc and the superexchange parameter J. Alteration of J is achieved by chemical modifications or external pressure. Measurements of J are done with: Neutron scattering, muon spin rotation (μSR), two magnon Raman scattering or resonant inelastic x-ray scattering. However, the experimental data is confusing. A recent Raman study showed an anticorrelation between Tc and J in the set of LnBa2Cu3Oy compounds with Ln=(La,..Lu,Y) [B.P.P. Mallet et al., Phys. Rev. Lett. 111, 237001 (2013)]. On the other hand, experimental measurements on the charge compensated 123 material (CaxLa1-x)(Ba1.75-xLa0.25+x)Cu3Oy (CLBLCO) inferred an overall positive correlation between Tc and J [D.S. Ellis et al., Phys. Rev. B 92, 104507 (2015)]. Thus, the effect of J on Tc is not established experimentally. In this talk I will review the experimental situation, mainly from the μSR viewpoint, and shed light on this controversy.

Fri., 22.09.2017 - Thu., 19.10.2017

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