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CuO 2 chains. A 14. Cu 2 O 3 ladders. b=12.9 Å. c C. c L. a=11.4 Å. Chains : Ladders : c C =2.75 Å c L =3.9 Å. 10 · c C ≈ 7 · c L ≈ 27.5 Å. c L / c C = √ 2. What is important in the ladders in Sr 14-x Ca x Cu 24 O 41 ?. Ladders: Non-linear conductivity.
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CuO2 chains A14 Cu2O3 ladders b=12.9 Å cC cL a=11.4 Å Chains: Ladders:cC=2.75 ÅcL=3.9 Å 10·cC≈7·cL≈27.5 Å cL/cC=√2
Ladders: Non-linear conductivity small non-linear effect Maeda et al., PRB’03 “large” non-linear effect Blumberg et al., Science’02
Ladders: Non-linear conductivity bad contacts, or large unnested voltage No ET, “large”non-linear effect good contacts and no unnested voltage No ET, negligible non-linear effect
2D phason response in ladder plane radio-freq. mode enhanced effective mass m*=102-103 pinned mode W0 Kitano et al., EPL’01
T* TCDW Phase diagram for ladders (corresponds to chains ph.diag.) suppresion of Tc and charge gaps 2D CDW in ladder plane unique to ladders? or common to low-D systems with charge order? order in ladders: CO oflocalized or CDW of itinerant electrons? analogy with AF/SDW half-filled ladder in Hubbard model: CDW+pDW in competition with d-SC Suzumura et al., JPSJ’04