1997 Fiscal Year Final Research Report Summary
Ultrafast dynamics of the photoinduced phase eransition
| Project/Area Number |
08454078
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
|
|---|
| Research Institution | Tokyo Institute of Technology |
|---|
Principal Investigator |
KOSHIHARA Shinya Dept.Appl.phys, Tokyo Institute of Technology, Associate Professor, 理学部, 助教授 (10192056)
|
|---|
| Project Period (FY) |
1996 – 1997
|
| Keywords | Photoinduced phase transition / phase transition dynamics / domain groth / N-I transition / diluted magnetic semiconductors / carriers |
|---|
| Research Abstract |
Various phase transitions occur in condensed matter due to the changes in external conditions such as temperature, pressure and magnetic field. It is an attractive target for material science to find a system which shows the phase transition triggered by external stimulation of electro-magnetic field of light. Of course, extensive studies have been made on the structural changes by optical pumping in the fields of photochemistry and solid-state physics for a long interval. However, those studies have been mainly concerned with microscopic reaction confined in small molecules or local structure change in crystals. Photo-induced cis-trans isomerization of stilbene, optically induced defect state in amorphous materials (fatigued photo-luminescence center) and self-trapped excition in alkaline-halide are typical examples of such a local structure change by photo-excitation. By contrast, we have reported experimental evidences indicating that the photo-injected local excitation can really trigger the macroscopic phase change by virtue of cooperative interaction in several crystals. In this sense, this unique photoinduced effect can be named as photoinduced phase transition (PIPT).
In the present study, we make a report on initial process of the neutral-ionic (N-I) phase transition in tetrathiafulvalene-chloranil (TTF-CA) studied by pico- and femto-second time-resolved spectroscopies, and photoinduced ferromagnetism in III-V based diluted magnetic semiconductors.
|
