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neutrons. muons. photons. Tuning the static spin-stripe phase and superconductivity in La 2- x Ba x CuO 4 ( x = 1/8) by hydrostatic pressure. Zurab Guguchia Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland. Tbilisi State University.
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neutrons muons photons Tuning the static spin-stripe phase and superconductivity in La2-xBaxCuO4 (x = 1/8) by hydrostatic pressure Zurab Guguchia Physik-Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
Tbilisi State University Thank you! University of Zürich in collaboration with: • Tbilisi State University, Georgia • Paul Scherrer Institute (PSI), Switzerland
1/8 problem THTT→LTO ≈ 200 K TLTO→LTT ≈ 50 K 0.11 <x≤ 0.13 Superconductivity in La2-xBaxCuO4 LTO A. R. Moodenbaugh et. al., Phys. Rev. B 38, 4596 (1988). J. D. Axe et. al., Phys. Rev. Lett. 62, 2751 (1989). M. Hücker et. al., Phys. Rev. B 83, 104506 (2011).
Stripe order in cuprate superconductors La1.48Nd0.4Sr0.12CuO4 J.M. Tranquada et. al., Nature (London) 375, 561 (1995). K.A. Moler, Nature468, 643-644 (2010). J. Zaanen, PRB 40, 7391 (1989).
Stripe order in La1.875Ba0.125CuO4 High-pressure studies on La1.875Ba0.125CuO4 have suggested that Tc of the system is restored under high pressure. Tso vs hydrostatic pressure? M. Hücker et. al., Phys. Rev. B 83, 104506 (2011).
Diamond anvil cell for high-pressure measurements Superconducting properties of La1.875Ba0.125CuO4
Muon-spin rotation (μSR) technique TRIUMF http://neutron.magnet.fsu.edu/muon_relax.html
time (ms) μSR in magnetic materials homogeneous inhomogeneous time (ms) amplitude → magnetic volume fractionfrequency → average local magnetic field damping → magnetic field distribution / magnetic fluctuations Courtesy of H. Luetkens
High pressure µSR experiments on La1.875Ba0.125CuO4 D. Andreica, Ph.D. thesis, IPP/ETH-Zürich, (2001).
Conclusions • The interplay between magnetism and superconductivity was studied in La1.875Ba0.125CuO4as a function of pressure up to p ≈ 2.25GPa. • At p = 0 static spin-stripe order is stabilized below Tso = 32 K, occupies nearly the whole sample volume and superconductivity exists in a minor part of the sample only. • The ordered moment size and the magnetic ordering temperature does not change upon application of pressure. However, the volume fraction of spin-stripe order significantly decreases with increasing p. • At the same time by the application of pressure SC phase volume increases proportionally to the non-magnetic volume fraction. • These results indicate that in La1.875Ba0.125CuO4 magnetism and superconductivity occur in mutually exclusive spatial regions.
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