Ultrasonic Propagation of a Metallic Domain inPr0.5Ca0.5CoO3Undergoing a Photoinduced Insulator-Metal Transition

Abstract

Femtosecond optical response was investigated on a perovskite-type cobalt oxide, Pr0.5Ca0.5CoO3 during an insulator-metal (I-M) transition accompanied with the change in spin configuration. After photoirradiation at 30 K, the reflectivity showed a sudden and large increase with subsequent variation depending on the observed photon energy. An exact calculation of Maxwell's equations for the Pr0.5Ca0.5CoO3 after the photoirradiation enabled us to observe the ultrafast dynamics of I-M phase transition and the motion of the photonically created metallic domain at the velocity of ultrasonic wave.

Slow Dynamics of the Photoinduced Phase Transition in Pd(dmit)2Salts (dmit = 1,3-dithiol-2-thione-4,5-dithiolate)

“…Most typical shape of the time prole was that of the probe photon energy of 1.31 eV which showed a broad peak at certain time delay. Similar peak in time prole of ∆R/R has been observed in Co oxide [8] and the origin has been attributed to the propagating motion of the domain boundary of the photoinduced state along the perpendicular direction from the sample surface. Then, we tried to analyse the time prole of Et 2 Me 2 Sb[Pd(dmit) 2 ] 2 based on similar model.…”

“…We have succeeded in reproducing the probe photon energy dependence of the time prole of ∆R/R qualitatively in the time delay range from 10 ps to 1 ns using the model proposed in Ref. [8]. We tentatively assigned the driving force for the domain boundary motion to the thermal diusive eect.…”

“…The rst one is the propagation of the photoinduced coherent phonon similar to PrCaCoO 3 [8]. In this case, the velocity of the domain boundary motion should be equal to the sound Fig.…”

“…[8], we assumed the following variation of the dielectric function (ε) in order to estimate the propagation of the photoinduced domain boundary…”

Femtosecond Reflection Spectroscopy in La1.5Sr0.5CoO4

“…Very lately, we reported PIPT and the resultant ultrasonic propagation of the photoinduced metallic region in Pr 0.5 Ca 0.5 CoO 3 [4,5]. In this paper, we chose a layered perovskite-type cobalt oxide, La 1.5 Sr 0.5 CoO 4 as a research target and explored a novel PIPT phenomenon in terms of a time resolved femtosecond reflection spectroscopy.…”