Title: Charge%20Inhomogeneity%20and%20Electronic%20Phase%20Separation%20in%20Layered%20Cuprate
1Charge Inhomogeneity and Electronic Phase
Separation in Layered Cuprate
F. C. Chou Center for Condensed Matter Sciences,
National Taiwan University National Synchrotron
Radiation Research Center, Taiwan
2Inhomogeneous Electron Density
3CDW, Dimerization and Nesting
1d Peierls instability q 2kF CDW gt MIT 2d
Fermi Surface nesting
Peierls Transition
4Phase Diagrams
5Charge Inhomogeneity Spin and charge stripes
La2-x-yNdySrxCuO4
- Holes segregate into AF antiphase domain walls
Tranquada et al, Nature 1995
6Spin/Charge Stripes and Superconductivity
Yamada et al, PRB 1998
71d domain walls in low x La2-xSrxCuO4
Cho et al, 1993
8Charge Inhomogeneity Checkerboard Type
Underdoped Bi2Sr2CaCu2O8d
Underdoped Ca2-xNaxCuO2Cl2
Hanaguri et al, Nature 2004
Hashimoto et al, PRB 2006
9Electrochemical oxygen intercalation
Grenier et al, Physica C 1991
10Macroscopic Phase Separation in La2CuO4d
La2CuO4d
- Electrochemical oxygen intercalation
- Undoped AF domain and hope-doped SC domain
Radaelli et al, PRB 1993 Statt et al, PRB 1995
11Spinodal Decomposition
12Staging charge/oxygen segregation
Wells et al, Science 1997
13Electrochemical oxygen intercalation
Grenier et al, Physica C 1991
14La2-xSrxCuO4d hole doping through Srx and Od
- Identical SC onset 40K
- SC volume fraction indep. of x or d
15La2-xSrxCuO4d magnetic phase by ZF-mSR
- Magnetic static ordering onset near 40K
- Magnetic volume fraction independent of x or d
16Phase Separation?
- Co-existing superconducting (SC) and magnetic
(ISDW) phases - Identical SC and ISDW onsets
- SC phase grows at the expense of ISDW phase
- Chemical or Electronic origin?
17Revisit LTT and ISDW
La2-xBa1/8CuO4 Non-SC La2-xSrxCuO4d SC
Structure ordering LTT LTO
Magnetic ordering 38K 3.5MHz 40K 3.5MHz
- Competing SC and ISDW, not LTT and ISDW
Luke et al, Physica C 1991
18LTT and 1/8 dip of Tc
19Why Electronic Phase Separation?
- t-J model by Emery and Kivelson
- Holes tend to phase separate but long-range
Coulomb repulsion frustrates phase separation - Competing AF correlation and Coulomb interaction
-
- quantum confinement, paired electrons
- Wigner crystal?
Löw, Emery, Fabricius, and Kivelson, PRL 1994
Xiuqing Huang, cond-mat/0606177
20Summary and Conclusions
- Large unexplored phase space
- PS of electronic origin indep. of x or d alone,
identical ISDW phase, competing SC and static
magnetic phases - Competing SC and ISDW, not SC and LTT
- The electronic interaction of the doped holes is
the primary driver of the phase separation rather
than specific chemistry of O or Sr in this
compound
Collaborators Hashini Mohottala and Barry Wells
(U. Conn.) et al, Nature Materials 2006
21Wigner crystals
Phys. Rev. Lett. vol. 86, p. 3851 (2001)
22Stripes in La2-xSrxCuO4
Marouchkine, 2006
Fujita et al, RRB 2002
23Staging behavior neutron scattering
PHYSICAL REVIEW B 69, 020502 (2004)