1. ISCOM2009 International symposium on crystalline organic metals, superconductors, ferromagnets announcement At Niseko in Hokkaido, Japan On Sep. 12 – 17, 2009 (Sep. 12; get-together)

2. New Aspects of Neutral-Ionic Transition (NIT) Revealed by Magnetic Resonance ECRYS2008, Cargese, Corsica, Aug. 25-30, 2008 K. Kanoda, Applied Physics, University of Tokyo 0.Introduction to NIT 1.Observation of quantum critical fluctuations in NIT 2.Separation of charge transfer and dimerization F. Iwase ( present; IMS), K. Miyagawa Y. Tokura, H. Okamoto S. Horiuchi K. Murata Collaborators Univ. Tokyo AIST Outline Osaka City Univ.

3. Neutral-Ionic transition (NIT) QCl 4 TTF TTF-QCl 4 paraelectric ferroelectric Neutral Ionic Torrance et al., PRL. (1981) Charge transfer -- Redox Dimerization --symmetry breaking Temperature Pressure Charge-lattice-coupled phenomena Spin-Peierls

4. NIT phase diagram Lemee-Cailleau et al. PRL 79, 1690 (1997) Okamoto et al. Neutral phase Ionic phase 1 st -order transition of simultaneous CT and dimerization TTF-QCl 4

5. NIT in DMTTF-QCl 4 –continuous and quantum DMTTF QCl 4 Horiuchi et al., J. Am. Chem. Soc., 123, 665 (2001). Chemical pressure Physical pressure by Horiuchi, Tokura Neutral Ionic Continuous transition

6. Nuclear quadrupole resonance (NQR) probes the charge state and symmetry of the lattice rf pulse I=3/2 Resonance frequency Electric field gradient (EFG) Charge transfer Dimerization nucleus Cl or Br nuclei e - e - Q Q line shift line splitting Cl or Br nuclei

7. NQR Ionic Neutral Spectral splitting QCl 4 Spectral shift Symmetry breaking (dimerization) Charge transfer Neutral Ionic TTF-QCl 4 Cl-NQR J. Gallier et al., Phys. Rev. B, 47, 11688 (1993). Iwase et al., JPSJ (2007)

8. NQR spectra

9. Spin-lattice relaxation rate 1/T 1 DMTTF-QBr 4 Br NQR T 0 ： Curie-Weiss temperature T 1 ： characteristic crossover temperature dividing the quantum and classical region Barrett formula: DMTTF-QCl 4 35 Cl NQR

10. P c (20K) =1.41 kbar P c (5K)=1.32 kbar  =0.55 20 K 5 K dimerization mean-field behavior R. Morf et al., PRB 16462 (1977). Pressure-induced NIT at low T NQR spectra at 5K

11. Pressure-induced NIT; continuous and quantum DMTTF-QBr 4 5 K T 1 ~(P c -P) 2.3 0.22 1/T 1 ~(P c -P) -2.3 1/T 1 ~(P c -P) -1 QBr 4 molecule 79 Br NQR Quantum critical fluctuations Spins are hidden all the way across the transition

12. Extended phase diagram of TTF-QCl 4 Dimer liquid Dimer crystal Long-range order Short-range order Charged spin soliton polarization

13. Two messages on NIT Critical fluctuations of N-I transition at low temperatures. They are likely quantum. Charge-lattice separation in low- energy scale in a wide P-T range.