of 22
8/3/2019 Michael Bertolli- Striping in Cuprates
1/22
Striping in Cuprates
Michael Bertolli
Solid State IIElbio Dagotto
Spring 2008
Department of Physics, Univ. of Tennessee
8/3/2019 Michael Bertolli- Striping in Cuprates
2/22
Outline
Introduction
Basics of Striping
Implications to Superconductivity
Experimental Findings Conclusion
8/3/2019 Michael Bertolli- Striping in Cuprates
3/22
Introduction
Superconductivity
Discovered in 1911: still a mystery
Related interesting phenomena
Striping
8/3/2019 Michael Bertolli- Striping in Cuprates
4/22
Basics
Used in 1990s to describe electrical/
magnetic property interactions
What is striping?
1D periodic ordering in 2D plane
Charge, spin, both
8/3/2019 Michael Bertolli- Striping in Cuprates
5/22
Basics
Electronic behaviour: 2 regimes
Kinetic energy dominated
Potential energy dominated
Between 2 regimes: stripes neither rigid lattice, nor delocalized
8/3/2019 Michael Bertolli- Striping in Cuprates
6/22
Where Is Striping
Found?
High TC superconductors: Cuprates
Cuprates
2D layered structure: sheets betweendoping material
AFM spin orientation
8/3/2019 Michael Bertolli- Striping in Cuprates
7/22
What is Striping?
Doping can introduces spinless free-charges
Movement frustrated by spins
Holes orient in 1D stripes to allow
movement at lower energy cost
No holes in regions between stripes
Spins in AFM order
8/3/2019 Michael Bertolli- Striping in Cuprates
8/22
What is Striping?
Electronic behaviour is quasi-1D
Coulomb coupling falls offexponentially
Anisotropic: metal or insulator
8/3/2019 Michael Bertolli- Striping in Cuprates
9/22
Implications to
Superconductivity
Cuprates doped below SC level show
striping
Doping corresponds to low TC
Striping competes with SC, with
some overlap
8/3/2019 Michael Bertolli- Striping in Cuprates
10/22
Implications to
Superconductivity
Only small overlap
8/3/2019 Michael Bertolli- Striping in Cuprates
11/22
Experimental Findings
Striping initially difficult to detect
Believed that stripes are mobile inthe lattice
Tranquada et al.: appropriate dopingcan immobilize stripes
Neutron scattering onLa1.48Nd0.4Sr0.12CuO4
8/3/2019 Michael Bertolli- Striping in Cuprates
12/22
Experimental Findings
sample at 11 K
Observed diffraction peakscorresponding to Cu spin ordering
La1.48Nd0.4Sr0.12CuO4
0.1cm3
8/3/2019 Michael Bertolli- Striping in Cuprates
13/22
Experimental Findings
sample at 11 K
Observed diffraction peakscorresponding to Cu spin ordering
La1.48Nd0.4Sr0.12CuO4
0.1cm3
8/3/2019 Michael Bertolli- Striping in Cuprates
14/22
Experimental Findings
Diffraction peaks characterized bytemperature
Magnetic stripes found below 3 K
Both stripes disappear before 70 K
8/3/2019 Michael Bertolli- Striping in Cuprates
15/22
Experimental Findings
Diffraction peaks characterized bytemperature
Magnetic stripes found below 3 K
Both stripes disappear before 70 K
8/3/2019 Michael Bertolli- Striping in Cuprates
16/22
4-probe resistivity measurements
Stripe ordered phase measurements
Striping frustrates 3D SC, not 2D
In-plane resistivity: SC
Out -of-plane resistivity: non-SC
La2xBaxCuO4
8/3/2019 Michael Bertolli- Striping in Cuprates
17/22
Spin incommensurability
Periodicity of spins are not alignedwith lattice
Also seen in
May be common feature of cuprates
La2xBaxCuO4
Y Ba2Cu3O7x
8/3/2019 Michael Bertolli- Striping in Cuprates
18/22
More Experiments!
U. of Connecticut group: phaseseparation
Used
Excess oxygen gives TC of 40 K
Observed simultaneous phaseseparation
La2xSrxCuO4+y
8/3/2019 Michael Bertolli- Striping in Cuprates
19/22
Simultaneous Phases
Competing phases coexist in sample:
Stripe ordered region with SCsuppressed
SC region exhibiting no stripe
ordering
8/3/2019 Michael Bertolli- Striping in Cuprates
20/22
Simultaneous Phases
Competing phases coexist in sample:
Stripe ordered region with SCsuppressed
SC region exhibiting no stripe
ordering
8/3/2019 Michael Bertolli- Striping in Cuprates
21/22
Conclusions
Anisotropic ordering of charge/spin
Striping is competing phase with SC
Exists in same temperature/dopingregime
Much work is needed to understand itsmechanism and role in SC
8/3/2019 Michael Bertolli- Striping in Cuprates
22/22
References[1] X.J. Zhou et al. One dimensional electronic structure and supression of d-wave
node state in (la1.28nd0.6sr0.12)cuo4. Science, 286, 1999.
[2] R. F. Service. Could charge stripes be a key to superconductivity? Science,283, 1999.
[3] J. Zaanen. Self-organized one dimensionality. Science, 286, 1999.
[4] V.J. Emery, S.A. Kivelson, and O. Zachar. Spin-gap proximity effect mecha-nism of high-temperature superconductivity. Phys. Rev. B, 56, 1997.
[5] S.A. Kivelson, I.P. Bindloss, E. Fradkin, V. Oganesyan, J.M. Tranquada,A. Kapitulnik, and C. Howald. How to detect fluctuating stripes in the high-temperature supercondutors. Rev. Mod. Phys., 75, 2003.
[6] J.M. Tranquada, B.J. Sternlieb, J.D. Axe, Y. Nakamura, and S. Uchida. Ev-idence for stripe correlations of spins and holes in copper oxide superconduc-tors. Nature, 375, 1995.
[7] Q. Li, M. Hucker, G.D. Gu, A.M. Tsvelik, and J.M. Tranquada. Two-
dimensional superconducting fluctuations in stripe-ordered la1.875ba0.125cuo4.Phys. Rev. Lett., 99, 2007.
[8] P. Dai, H.A. Mook, and F. Dogan. Incommensurate magnetic fluctuations inyba2cu3o6.6. Phys. Rev. Lett., 1998.
[9] H.E. Mohottala et al. Phase spearation in superoxygenated la2xsrxcuo4+y.Nature Materials, 5, 2006.
[10] S.A. Kivelson. Superconducting materials: Superconductivity on the verge ofcatastrophe. Nature Materials, 5, 2006.