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TT: Fachverband Tiefe Temperaturen
TT 47: Poster Session Correlated Electrons 2
TT 47.9: Poster
Mittwoch, 18. März 2020, 15:00–19:00, P2/3OG
Ultrafast dynamics in transition-metal dichalocogenide IrTe2 — •Amrit R Pokharel1, Meng Yang2, You Guo Shi2, Tao Dong1, and Jure Demsar1 — 1Uni Mainz, Germany — 2Institute of physics, CAS, China
Layered transition-metal dichalocogenide IrTe2 undergoes a structural phase transition to a(1/8, 0, 1/8) modulated state at Tc 280 K, followed by a transition to a(1/5, 0, 1/5) lattice modulated phase around 170 K. The low temperature modulated phase is further accompanied by the emergence of superconductivity below 2 K. Upon warming, the low temperature (1/5, 0, 1/5) lattice modulated phase persist up to Tc 280 K without entering into the (1/8, 0, 1/8) modulated state. The structural phase transitions are accompanied by sharp jumps in resistivity, indicating a complex electronic modulation entangled with structural phase transition. Despite the extensive studies, origins of the structural phase transitions and possible non-thermal light induced phase transitions remain elusive. We study the carrier relaxation dynamics and collective modes in different phases of IrTe2 utilizing time-resolved pump-probe spectroscopy. Upon cooling below 280 K we observe the emergence of A1g modes at 1.28 THz and 2.17 THz. Upon further cooling through 170 K the 2.17 THz mode is dramatically reduced and new modes appear near 2.52 THz. On warming up from liquid-He temperatures the low frequency phonon modes remain unchanged up to 280 K, without entering the intermediate phase. These observations suggest the coherent phonon spectroscopy to be a sensitive tool to probe the symmetry breaking phase transitions.