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Photons muons neutrons Tuning the static spin-stripe phase and superconductivity in La 2-x Ba x CuO 4 (x = 1/8) by hydrostatic pressure Zurab Guguchia.

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Presentation on theme: "Photons muons neutrons Tuning the static spin-stripe phase and superconductivity in La 2-x Ba x CuO 4 (x = 1/8) by hydrostatic pressure Zurab Guguchia."— Presentation transcript:

1 photons muons neutrons 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

2 Collaborators Alexander Maisuradze Hugo Keller Alexander Shengelaya Ekaterina Pomjakushina Kazimierz Conder Rustem Khasanov Tbilisi State University Universität Zürich UZH

3 Thank you! University of Zürich in collaboration with: Tbilisi State University, Georgia Paul Scherrer Institute (PSI), Switzerland Tbilisi State University

4 Superconductivity in La 2-x Ba x CuO 4 J. D. Axe et. al., Phys. Rev. Lett. 62, 2751 (1989). M. Hücker et. al., Phys. Rev. B 83, (2011). T LTO→LTT ≈ 50 K T HTT→LTO ≈ 200 K A. R. Moodenbaugh et. al., Phys. Rev. B 38, 4596 (1988). 1/8 problem LTO 0.11 < x ≤ 0.13

5 Stripe order in cuprate superconductors K.A. Moler, Nature 468, (2010). J. Zaanen, PRB 40, 7391 (1989). La 1.48 Nd 0.4 Sr 0.12 CuO 4 J.M. Tranquada et. al., Nature (London) 375, 561 (1995).

6 La 2-x Ba x CuO 4 La 1.8-x Eu 0.2 Sr x CuO 4 G.M. Luke et. al., Physica C , (1991). M. Hücker et. al., Physica C , 170(2007).

7 Stripe order in La Ba CuO 4 M. Hücker et. al., Phys. Rev. B 83, (2011). High-pressure studies on La Ba CuO 4 have suggested that T c of the system is restored under high pressure. T so vs hydrostatic pressure?

8 Superconducting properties of La Ba CuO 4 Diamond anvil cell for high-pressure measurements

9 Muon production/decay and parity violation The muon beam is 100 polarised with S µ antiparallel to P µ.

10 Muon-spin rotation (μSR) technique B μ = (2π/γ μ ) ν μ local B-field at the muon site

11 TRIUMF Muon-spin rotation (μSR) technique

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13 Courtesy of H. Luetkens homogeneous amplitude → magnetic volume fraction frequency → average local magnetic field damping → magnetic field distribution / magnetic fluctuations time (  s) μSR in magnetic materials inhomogeneous

14 High pressure µSR experiments on La Ba CuO 4 D. Andreica, Ph.D. thesis, IPP/ETH-Zürich, (2001).

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16 High pressure µSR experiments on La Ba CuO 4

17 Phase diagrams

18 Conclusions  The interplay between magnetism and superconductivity was studied in La Ba CuO 4 as a function of pressure up to p ≈ 2.25 GPa.  At p = 0 static spin-stripe order is stabilized below T s o = 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 La Ba CuO 4 magnetism and superconductivity occur in mutually exclusive spatial regions.

19 Thank you very much for your attention! Thank you very much for your attention!

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21 M. Hücker et. al., PRL 104, (2010).

22 B. Nachumi et. al., PRB 58, 8760 (1998).


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