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The spin-SAF Transition in the Quarter-Filled Ladder Compound NaV 2 O 5

Gennady Y. Chitov Laurentian University Sudbury, Ontario, Canada in collaboration with Claudius Gros Frankfurt University Frankfurt, Germany. The spin-SAF Transition in the Quarter-Filled Ladder Compound NaV 2 O 5. Phase Transition in NaV 2 O 5 : Experiment. 1/4-filled ladder compound:

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The spin-SAF Transition in the Quarter-Filled Ladder Compound NaV 2 O 5

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  1. Gennady Y. ChitovLaurentian UniversitySudbury, Ontario, Canadain collaboration withClaudius GrosFrankfurt UniversityFrankfurt, Germany The spin-SAF Transition in the Quarter-Filled Ladder Compound NaV2O5

  2. Phase Transition in NaV2O5: Experiment • 1/4-filled ladder compound: • Smolinski, et al, 1998 • Spin Gap: • Isobe & Ueda, 1996 • 2D charge order: • van Smaalen, et al, 2002 • Grenier, et al, 2002 • Chitov & Gros, 2004 (SAF) • Phase transition: • Thermal, close to 2D Ising universality class • Ravy, et al, 1999 • Gaulin, et al, 2000 • Fagot-Revurat, et al, 2000 Mechanism: spin-Peierls - NO Charge+Spin - ??

  3. Model and Approximation

  4. Spin-Pseudospin (Coupled) Model: Phase Diagram • Coupled Model always orders viaspin-SAF transition • QCP is destroyed Coupled Model Quantum Ising Model

  5. Spin-SAF Theory: Application to NaV2O5 E0 Optical Conductivity: Damascelli, et al, 2000.

  6. Summary &Discussion 1. Spin-pseudospin model is proposed and the theory of spin-SAF transition is developed. Spin-SAF phase = simultaneous Super-AntiFerroelectric (SAF) charge order + spin gap. 2. Numerical parameters of the effective Hamiltonian Peaks in the optical conductivity, absence of the soft mode 3. Further progress: (i) Marginal (log-) corrections for XXX-chains Tc, BCS-ratio (work in progress) (ii) Ising (pseudospin, i.e., charge) sector beyond mean-field (??)

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