Search results

1

Growth Dynamics of Photoinduced Phase Domain in Cyano-Complex Studied by Boundary Sensitive Raman Spectroscopy

100%

Asahara A., Nakajima M., Fukaya R., Tokoro H., Ohkoshi S., Suemoto T.

Acta Physica Polonica A

|

2012

|

vol. 121

|

issue 2

375-384

EN

Rubidium manganese hexacyanoferrate exhibits charge transfer phase transition from high temperature phase to low temperature phase at 230 K. This phase transition can also be triggered by light irradiation resonantly inducing charge transfer from Mn^{2+} to Fe^{3+}. In the present study, boundary sensitive Raman spectroscopy was performed for Rb_{0.94}Mn[Fe(CN)_6]_{0.98}·0.2H_2O in both cases of photoinduced and thermal phase transition. Since the frequencies of C ≡ N stretching vibration modes are very sensitive to the valence states of the adjacent metal ions, we can quantify the distribution of not only high and low temperature phase but also boundary configurations from the observed spectra. We obtained the time evolution of the fraction ratios of the valence states from the observed peak areas. In the case of photoinduced situation, the boundary increases up to 15% when high temperature phase diminishes to 55% of the initial fraction. This is quite different from the result in thermal phase transition where the boundary is created only 0.8% at the same high temperature phase fraction value. We conclude that many small domains are preferably created in photoinduced phase transition since the ratio of boundary is large, while large domains grow in thermal phase transition.

2

Photoinduced Phase Transition in Pr_{0.5}Ca_{0.5}CoO_3 Studied by Sequential Pulse Excitations

84%

Seko K., Okimoto Y., Kurashima M., Fukaya R., Egawa T., Ishikawa T., Onda K., Koshihara S., Kyomen T., Itoh M.

Acta Physica Polonica A

|

2012

|

vol. 121

|

issue 2

369-371

EN

A perovskite-type cobalt oxide, Pr_{0.5}Ca_{0.5}CoO_3 (PCCO), shows photoinduced phase transition. In this study, we successively irradiated two laser pulses with different intensities to PCCO and probed the transient change of the reflection at 2.0 eV. Assuming propagation of the two different photoinduced metallic states, we could reproduce the time profiles as well as the magnitude in the reflectance change, indicating the fabrication of the photoinduced multilayered thin film in Pr_{0.5}Ca_{0.5}CoO_3.

3

Femtosecond Reflection Spectroscopy in La_{1.5}Sr_{0.5}CoO_4

84%

Egawa T., Okimoto Y., Fukaya R., Onda K., Ishikawa T., Koshihara S., Isayama A., Sasagawa T.

Acta Physica Polonica A

|

2012

|

vol. 121

|

issue 2

307-309

EN

Ultrafast optical response has been investigated using fs laser system on a perovskite-type cobalt oxide, La_{1.5}Sr_{0.5}CoO_4. After the photoirradiation at room temperature, the time profile of relative change of reflectance (Δ R/R) shows a sudden change within the pulse duration ( ≈ 150 fs) and decays with a lifetime of ≈ 330 fs. The sign of Δ R/R after the photoexcitation is positive in the mid-infrared region (at 0.50 eV) while negative in the visible energy region (at 2.0 eV), implying photoinduced change of the electronic structure after the photoexcitation.

4

Ultrafast Dynamics of Photoinduced Electronic Phase Modulation in Ladder Cuprate of Sr_{14 - x}Ca_{x}Cu_{24}O_{41}

84%

Fukaya R., Kunitomo M., Okimoto Y., Ishikawa T., Onda K., Koshihara S., Yui H., Sasagawa T.

Acta Physica Polonica A

|

2012

|

vol. 121

|

issue 2

310-312

EN

Ultrafast carrier dynamics caused by photoexcitation in quasi-one-dimensional two-leg ladder cuprate Sr_4Ca_{10}Cu_{24}O_{41} was investigated by the femtosecond reflection spectroscopy. After the photoexcitation along the leg direction, the transient reflectivity changes (Δ R/R) in the mid-infrared region showed instant decrease within 150 fs. The suppressed Δ R/R increased so rapidly on the picosecond time scale that the reflectivity value finally became larger than that in the initial state. Such a successive response in Δ R/R, which was also observed in other photon energy regions, is discussed in terms of ultrafast variation of the Drude weight in the ladder system by the photoirradiation.

Refine search results

4 Acta Physica Polonica A

4 2012

4 Fukaya R.

3 Ishikawa T.

3 Koshihara S.

3 Okimoto Y.

3 Onda K.

2 Egawa T.

2 Sasagawa T.

1 Asahara A.

1 Isayama A.

1 Itoh M.

1 Kunitomo M.

1 Kurashima M.

1 Kyomen T.

1 Nakajima M.

1 Ohkoshi S.

1 Seko K.

1 Suemoto T.

1 Tokoro H.

1 Yui H.

Growth Dynamics of Photoinduced Phase Domain in Cyano-Complex Studied by Boundary Sensitive Raman Spectroscopy

Photoinduced Phase Transition in Pr_{0.5}Ca_{0.5}CoO_3 Studied by Sequential Pulse Excitations

Femtosecond Reflection Spectroscopy in La_{1.5}Sr_{0.5}CoO_4

Ultrafast Dynamics of Photoinduced Electronic Phase Modulation in Ladder Cuprate of Sr_{14 - x}Ca_{x}Cu_{24}O_{41}