Unequal on-site interaction effects in the one-dimensional electron system at quarter filling

The one-dimensional antiferromagnetic correlated electron system described by the unusual t–U–J model with alternating on-site interactions at odd ($$U_o$$ U o ) and even ($$U_e$$ U e ) sites is studied analytically. At weak coupling, the use of bosonization and renormalization-group techniques helps to obtain ground-state phase diagram. At quarter filling, the unequal on-site repulsion ($$U_e\ne U_o$$ U e ≠ U o ) causes the occurrence of umklapp processes and the generation of a charge excitation gap. Contrary to the usual case ($$U_e=U_o$$ U e = U o ), the system is not metallic but insulating. For $$U_e+U_o<2J$$ U e + U o < 2 J , the system is in a spin-gapped phase with charge-density-wave (CDW) instability; for $$U_e+U_o\ge 2J$$ U e + U o ≥ 2 J , the system is in a spin-gapless phase characterized by the coexistence of both CDW and spin-density-wave (SDW) instabilities, where the SDW correlation dominates over the CDW one.

Fabrication of the electric double layer transistor with (La,Pr,Ca)MnO3 nanowall wire channel

In the scaling down of electronic devices, functional oxides with strongly correlated electron system provide advantages to conventional semiconductors. We report the fabrication of the electric double layer transistor (EDLT) with the (La,Pr,Ca)MnO3 (LPCMO) epitaxial nanowall wire (NW) channel whose width was less than 100 nm. The width controlled LPCMO NWs were fabricated using an original nanofabrication technique: 3D nanotemplate pulsed laser deposition. The LPCMO NW EDLT was produced by employing 80 nm width NWs as channel. The produced LPCMO NW EDLT showed low leakage current. The metal-insulator transition property was successfully modulated by gating effect on the LPCMO NW EDLT.

Excitation and Relaxation Dynamics of the Photo-Perturbed Correlated Electron System 1T-TaS2

We investigate the perturbation and subsequent recovery of the correlated electronic ground state of the Mott insulator 1T-TaS 2 by means of femtosecond time-resolved photoemission spectroscopy in normal emission geometry. Upon an increase of near-infrared excitation strength, a considerable collapse of the occupied Hubbard band is observed, which reflects a quench of short-range correlations. It is furthermore found that these excitations are directly linked to the lifting of the periodic lattice distortion which provides the localization centers for the formation of the insulating Mott state. We discuss the observed dynamics in a localized real-space picture.