Femtosecond Spectroscopy of Ultrafast Dynamics in Spin Crossover Cobalt Perovskites

<strong>Seminar of the School of Physical Sciences --------------------------------------------------</strong> <strong>Femtosecond Spectroscopy of Ultrafast Dynamics in Spin Crossover Cobalt Perovskites</strong> <strong>Yoichi Okimoto&nbsp;</strong> (Tokyo Institute of Technology, Tokyo) Date:&nbsp;<strong>November 17, 2016</strong> <strong>Abstract:</strong>&nbsp;Photonic control of the electronic property of solids has been of current interest in condensed matter physics. Among many solids, spin crossover (SC) complexes are known to show so called photoinduced phase transition (PIPT). This is a photonic change/control of the spin state of d electrons in the transition metal element between the low spin (LS) state (t2g6) and the high spin (HS, eg2 t2g4) state. In addition to those organic complexes, a perovskite-type cobalt oxide is also an interesting example showing such a spin state transition with an insulator-metal transition, and we have so far demonstrated that some SC cobalt oxides showed unique ultarafast PIPT[1-5]. In this presentation, we show PIPT phenomena in some perovskite-type cobalt oxides undergoing the SC phenomenon, and discuss the ultrafast dynamics of the photoinduced state after the photoirradiation in terms of femtosecond pump-probe spectroscopy. References [1] Y. Okimoto et al., Phys, Rev. Lett. 103, 027402 (2009) [2] Y. Okimoto et al., Phys, Rev. B 83, 161101(R) (2011) [3] Y. Okimoto et al., Phys. Rev. B, 84, 121102(R) (2011) [4] K. Seko, Y. Okimoto et al., Act. Phys. Pol. A, 121, 369 (2012) [5] Y. Okimoto et al., J. Phys. Soc. Jpn., 82, 187401 (2013)