Zurab Guguchia Physik-Institut der Universität Zürich, Winterthurerstrasse 190,

photons

muons

neutrons

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

Thank you!Thank you!

University of Zürich in collaboration with:

• Tbilisi State University, Georgia

• Paul Scherrer Institute (PSI), Switzerland

Tbilisi State University

Superconductivity in La2-xBaxCuO4

J. D. Axe et. al., Phys. Rev. Lett. 62, 2751 (1989).

M. Hücker et. al., Phys. Rev. B 83, 104506 (2011).

TLTO→LTT ≈ 50 KTHTT→LTO ≈ 200 K

A. R. Moodenbaugh et. al., Phys. Rev. B 38, 4596 (1988).

1/8 problem

LTO

0.11 < x ≤ 0.13

Stripe order in cuprate superconductors

K.A. Moler, Nature 468, 643-644 (2010).

J. Zaanen, PRB 40, 7391 (1989).

La1.48Nd0.4Sr0.12CuO4

J.M. Tranquada et. al., Nature (London) 375, 561 (1995).

Stripe order in La1.875Ba0.125CuO4

M. Hücker et. al., Phys. Rev. B 83, 104506 (2011).

High-pressure studies on La1.875Ba0.125CuO4 have suggested that Tc of the system is restored under high pressure.

Tso vs hydrostatic pressure?

Superconducting properties of La1.875Ba0.125CuO4

Diamond anvil cell for high-pressure measurements

TRIUMF http://neutron.magnet.fsu.edu/muon_relax.html

Muon-spin rotation (μSR) technique

Courtesy of H. Luetkens

0 1 2 3 4 5 6 7 8 9 10-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Muo

n S

pin

Pol

aris

atio

n

Time (s)

0 1 2 3 4 5 6 7 8 9 10-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Muo

n S

pin

Pol

aris

atio

n

Time (s)

homogeneous

amplitude → magnetic volume fractionfrequency → average local magnetic field damping → magnetic field distribution / magnetic fluctuations

0 1 2 3 4 5 6 7 8 9 10-1.0

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Muo

n S

pin

Pol

aris

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Time (s)time (s)

time (s)

μSR in magnetic materials

inhomogeneous

High pressure µSR experiments on La1.875Ba0.125CuO4

. , , ,

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D. Andreica, Ph.D. thesis, IPP/ETH-Zürich, (2001).

High pressure µSR experiments on La1.875Ba0.125CuO4

Phase diagrams

Conclusions

The interplay between magnetism and superconductivity was studied in La1.875Ba0.125CuO4 as a function of pressure up to p ≈ 2.25 GPa.

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.

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