We report a genuine phase diagram for a disorder-free CuO 2 plane based on the precise evaluation of the local hole density (N h ) by site-selective Cu-NMR studies on five-layered high-T c cuprates. It has been unraveled that (1) the antiferromagnetic metallic state (AFMM) is robust up to N h % 0:17, (2) the uniformly mixed phase of superconductivity (SC) and AFMM is realized at N h 0:17, (3) the tetracritical point for the AFMM/(AFMM+SC)/SC/PM (paramagnetism) phases may be present at N h % 0:15 and T % 75 K, (4) T c is maximum close to a quantum critical point (QCP) at which the AFM order collapses, suggesting the intimate relationship between the high-T c SC and the AFM order. The results presented here strongly suggest that the AFM interaction plays the vital role as the glue for the Cooper pairs, which will lead us to a genuine understanding of why the T c of cuprate superconductors is so high.

We study heavy baryons with an exotic flavor quantum number formed by a heavy meson and a nucleon ( " DN and BN) through a long range one pion exchange interaction. The bound state found previously in the ðI; J P Þ ¼ ð0; 1=2 À Þ channel survives when short range interaction is included. In addition, we find a resonant state with ðI; J P Þ ¼ ð0; 3=2 À Þ as a Feshbach resonance predominated by a heavy vector meson and a nucleon ( " D Ã N and B Ã N). We find that these exotic states exist for the charm and heavier flavor region.

We consider a uniform dipolar Fermi gas in two-dimensions (2D) where the dipole moments of fermions are aligned by an orientable external field. We obtain the ground state of the gas in HartreeFock approximation and investigate RPA stability against density fluctuations of finite momentum. It is shown that the density wave instability takes place in a broad region where the system is stable against collapse. We also find that the critical temperature can be a significant fraction of Fermi temperature for a realistic system of polar molecules.

Photoluminescence ͑PL͒ properties of heavily P-and B-doped Si nanocrystals ͑nc-Si͒ are studied. By simultaneously doping two types of impurities, nc-Si exhibit strong PL at around 0.9 eV at room temperature. The temperature quenching of the PL is very small. Although the PL peak energy is very close to that of dangling-bond related PL previously observed, all of the observed properties, i.e., decay dynamics, degree of temperature quenching, etc., are apparently different. The transition between donor and acceptor states in nc-Si is the possible origin of the low-energy PL.

The effects of B and P codoping on photoluminescence (PL) properties of Si nanocrystals (nc-Si) are studied systematically. It is shown that the PL intensity of codoped nc-Si is always higher than that of either P-or B-doped nc-Si. The intensity is sometimes even higher than that of pure nc-Si at relatively low P and B concentrations and low annealing temperatures. By doping P and B simultaneously to very high concentrations, the PL peak shifts below the band gap of bulk Si.