Theoretical study of anomalous liquid states in lowdimensional fermion systems
Project/Area Number  10203206 
Research Category 
GrantinAid for Scientific Research on Priority Areas (B).

Research Institution  University of Tokyo 
Principal Investigator 
OGATA Masao University of Tokyo, Department of Physics, Graduate School of Science, Assistant Professor, 大学院・理学系研究科, 助教授 (60185501)

Project Fiscal Year 
1998 – 2000

Project Status 
Completed(Fiscal Year 2001)

Budget Amount *help 
¥4,400,000 (Direct Cost : ¥4,400,000)
Fiscal Year 2000 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1999 : ¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1998 : ¥800,000 (Direct Cost : ¥800,000)

Keywords  onedimensional fermion systems / TomonagaLuttinger liquid / spin gap / charge density wave / frustration / 1次元フェルミ粒子系 / 朝永・ラッティンジャー液体 / スピンギャップ / 電荷密度波 / フラストレーション / 低次元 / 液体ヘリウム 
Research Abstract 
In the fermion systems in lowdimensiorial geometries, it is believed that an anomalous state called as TomonagaLuttinger liquid is realized. We have studied several issues about its properties and obtained some new results as follows. 1) In the case where there is an excitation gap for the spin degrees of freedom, we have studied the behaviors of spectrum of Green's functions, spin response functions and charge response functions. We have found characteristic correlation exponents which are different from the conventional ones. 2) We have developed perturbative calculations for the quasionedimensional model and found a crossover from purely onedimensional behavior to twodimensional behaviors. 3) We have studied the mechanism and temperature dependence of the coexistence of charge density wave and spin density wave. Especially using a renormalization group technique, we found that there are two possible coexistent states and a crossover occurs as a function of temperature. 4) Considering the spincharge separation, we studied variationally the ground states of twolayered onedimensional fermion systems. There are several interesting magnetic states depending on the density in the second layer. A frustrationinduced melting of the charge density wave has been also investigated. 5) We have studied the possibilities of stripe states where charges are localized in onedimensional stripes and the system is decomposed into localized spin region and onedimensional charge liquid. 6) Using a model in which there is a shortrange repulsion between onedimensional bosons, we have studied the Green's function and clarified the difference from the fermion systems 6)1次元ボース粒子間に強い短距離斥力が働くというモデルを用いて、グリーン関数の振舞いなどを調べ、よく知られているフェルミ粒子系との類似点、相違点を明らかにした。

Report
(5results)
Research Output
(15results)