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Ultrafast dynamics of SrCd<sub>2</sub>Sb<sub>2-x</sub>As<sub>x</sub> single crystals studied by optical pump-probe spectroscopy

ORAL

Abstract

Topological materials exhibiting symmetry-protected surface states such as topological insulators have recently gained attention due to its unique physical properties and potential applications. In this context, the present study utilizes AB2X2 type SrCd2Sb2-xAsx single crystals to study the ultrafast dynamics of carriers and phonons to gain insight into critical changes in crystal structure through chemical substitution. Here, we use optical pump-probe (OP-OP) spectroscopy on the as-synthesized SrCd2Sb2, SrCd2As2, and As (x=0.1) doped SrCd2As0.1Sb1.9 single crystals. The transient reflectivity (ΔR/R) curve shows similar fitting behavior and paramters for SrCd2Sb2 and SrCd2As0.1Sb1.9 which is in contrast to SrCd2As2. The significant observations from the OP-OP measurements include, (i) absence of sub-ps decay component in SrCd2Sb2, (ii) appearance of ∼10 ps decay term (τ3) for SrCd2Sb2, and (iii) the change of sign for the amplitude (A2) of several ps τ2 decay term. The results revealed contrast ultrafast dynamics between SrCd2As2 and SrCd2Sb2 thereby implying that SrCd2As2 and SrCd2Sb2 have distinct electronic structures near the band edge. Further, we will carry out OP-OP measurements for the whole doping range (x=0.1 to 2.0) in SrCd2Sb2-xAsx to elucidate the evolving electronic band structure and to observe the desired transition in ultrafast spectroscopy around x = 1.0.

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Presenters

  • Jiunn-Yuan Lin

    National Yang Ming Chiao Tung University, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

Authors

  • Nidhi Puri

    National Yang Ming Chiao Tung University, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Jiunn-Yuan Lin

    National Yang Ming Chiao Tung University, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Chih-Wei Luo

    National Yang Ming Chiao Tung University, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Chien-Ming Tu

    National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Wen-Yen Tzeng

    National Yang Ming Chiao Tung University, National Yang Ming Chiao Tung University, Hsinchu, Taiwan, Department of Electrophysics, National Yang Ming Chiao Tung University

  • Chi-Chen Tsai

    National Yang Ming Chiao Tung University, National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Po-Wei Gong

    National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Yi-Cheng Cheng

    National Yang Ming Chiao Tung University, Hsinchu, Taiwan

  • Jiun-Haw Chu

    University of Washington, University of Washington, Seattle, Washington, USA

  • Cheng-Chien Chen

    University of Alabama at Birmingham, University of Alabama at Birmingham, Birmingham, Alabama, USA