Zurab Guguchia
Physik-Institut der Universität Zürich, SwitzerlandLaboratory for Muon Spin Spectroscopy, Paul-Scherrer Institut, Switzerland
Negative Oxygen Isotope Effect on the Static Spin Stripe Order in La1.875Ba0.125CuO4
Thank you!
Markus Bendele
Hugo Keller
Laboratory for Muon Spin Spectroscopy (PSI)
Rustem Khasanov
Laboratory for Developments and Methods (PSI)
Ekaterina Pomjakushina
Kazimierz Conder
Alexander Shengelaya
Tbilisi State University
Outline
• Introduction Stripe phase in cuprates. Isotope effects. Muon Spin Rotation (µSR) technique.
• Results Oxygen Isotope Effect (OIE) on superconductivity in LBCO-1/8. OIE on the static spin stripe order in LBCO-1/8. Pressure effects in LBCO-1/8.
• Conclusions
Superconductivity in La2-xBaxCuO4
Moodenbaugh et al, Phys. Rev. B 38, 4596 (1988).
Axe et al, Phys. Rev. Lett. 62, 2751 (1989).
Hücker et al, Phys. Rev. B 83, 104506 (2011).
Experimental evidence for static stripes in La1.48Nd0.4Sr0.12CuO4
Neutron Scattering
Tranquada et al, Nature (London) 375, 561 (1995).
Guguchia, PhD thesis,University of Zürich (2013).
Real spaceSpin order
Charge order
M. Vojta, Adv. Phys. 58, 699 (2009) and references therein.T. Wu et. al., Nature 477, 191 (2011).
Central issues in Cuprates
What is microscopic origin of the stripe formation?The stripe phase may be caused by electronic and/or electron-lattice
interaction.
Do stripes promote or inhibit superconductivity?
Zaanen and Gunnarson Phys. Rev. B 40, 7391 (1989).
White and Scalapino, PRL 80, 1272 (1998).
Emery and Kivelson, Physica C 209, 597 (1993).
M. Vojta, Adv. Phys. 58, 699 (2009).
Do they contain all ingredients required for stripe formation?
Conventional superconductivity
Electron-phonon interaction
Isotope effect:
.ln/ln-
,
MdTd
MT
c
c
Ranges from 0.2-0.5 in elemental metals
Weak coupling BCS predicts a value of a = 0.5
C.A. Reynolds et. al., Phys. Rev. 78, 487 (1950).E. Maxwell, Phys. Rev. 78, 477 (1950).
J. Bardeen et. al., Phys. Rev. 108, 1175 (1957).
Unconventional Oxygen Isotope effects (OIE’s) in cuprates
J. Hofer et. al., PRL 84, 4192 (2000).K.A. Müller, J. Phys. Condens. Matter 19, 251002 (2007).H. Keller et. al., Materials today 11, 9 (2008).
Shengelaya et. al, PRL 83, 24 (1999).Khasanov et. al., PRL 101, 077001 (2008).Lanzara et. al., J. Phys. Condens. Matter 11, L541 (1999). Rubio Temprano et. al., PRL 84, 1990 (2000).Zhech et. al., Nature 371, 681–683, 1994.
Isotope effect on Tc near 1/8
M.K. Crawford et. al., Science 250, 1390 (1990). G.M. Zhao et. al., J. Phys.: Condens. Matter 10, 9055 (1998).J.P. Franck et. al., PRL 71, 283 (1993). J. Hofer et. al., PRL 84, 4192 (2000).B. Batlogg et. al., PRL 59, 912 (1987). G.Y. Wang et. al., PRB 75, 212503 (2007).
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
atio
n
Time (s)time (ms)
time (ms)
μSR in magnetic materials
inhomogeneous
Magnetization experiments
Tranquada et. al., PRB 78, 174529 (2008). Li et. al., PRL 99, 067001 (2007).Z. Guguchia et al., New Journal of Physics 15, 093005 (2013).
Z. Guguchia et al., Phys. Rev. Lett. (2014).
Isotope effect on Tc in La1.875Ba0.125CuO4
.ln/ln-
K. 1)(3.28 andK 29.7(1) . 118
116
MdTd
TTMT
c
ccc
Z. Guguchia et al., Phys. Rev. Lett. (2014).
Oxygen Isotope effect on Tso
bTTT
aATAsoso
1]/)exp[(
11)0(/)(
Z. Guguchia et al., Phys. Rev. Lett. (2014).
bTTT
aATAsoso
1]/)exp[(
11)0(/)( K. 2)(8.34 andK 32.9(3) 1816 soso TT
Oxygen Isotope effect on Tso
Z. Guguchia et al., Phys. Rev. Lett. (2014).
G.M. Luke et. al., Physica C 185-9, 1175 (1991).B. Nachumi et. al., PRB 58, 8760 (1998).
Oxygen Isotope effect on Tso
bTTT
aATAsoso
1]/)exp[(
11)0(/)( K. 2)(8.34 andK 32.9(3) 1816 soso TT
Z. Guguchia et al., Phys. Rev. Lett. (2014).
OIE effect on Tso and magnetic fraction Vm
Z. Guguchia et al., Phys. Rev. Lett. (2014).
Summary of the OIE studies on La1.875Ba0.125CuO4
.)9(71.0 ),6(57.0 mSO VT
Give evidence for stripe-lattice coupling in cuprates.
Superconductivity and stripe order are competing phenomena.
0.46(6). ),6(57.01
cSO TT
Pressure experiments with SQUID and µSR
Z. Guguchia et al., New Journal of Physics 15, 093005 (2013).
SQUID (Maisuradze and Guguchia) µSR (R. Khasanov)
Pressure effect on static spin-stripe order in La1.875Ba0.125CuO4
Vsc(0) + Vm(0) ≈ 1
Z. Guguchia et al., New Journal of Physics 15, 093005 (2013).
LTT structural phase under pressure
Hücker et al, PRL 104, 057004 (2010).
Pressure effect on the isotope effect inLBCO-1/8
Conclusions
Large negative OIE’s were observed on Tso and Vm in La2-xBaxCuO4 (x = 1/8).
Oxygen-isotope shifts of Tc and TSO are sign reversed. Stripe order and superconductivity are competing orders.
The electron-lattice interaction is involved in the stripe formation and is a crucial factor controlling the competition between the stripe order and superconductivity.
A purely electronic mechanism can not explain the present isotope and pressure experiments!
Thank you very much for your attention!Thank you very much for your attention!
