TY - JOUR
T1 - Anomalous pressure dependence of phonon line widths in metallic pyrochlore iridates (Eu 1-x Bi x) 2 Ir 2 O 7
T2 - crossover from incoherent to coherent metal
AU - Thomas, Anoop
AU - Telang, Prachi
AU - Rout, Dibyata
AU - Mishra, Kshiti
AU - Pal, Anand
AU - Muthu, D. V.S.
AU - Kumar, P. S.Anil
AU - Singh, Surjeet
AU - Sood, A. K.
N1 - Funding Information:
AKS thanks the Department of Science and Technology, Government of India, for financial support under the Year of Science Professorship and Nano Mission Council. AT acknowledges support from the Council for Scientific and Industrial Research (CSIR), India. SS would like to thank the Department of Science and Technology (DST), India and Science and Engineering Research Board (SERB), India for financial support under Grant No. EMR/2016/003792. The authors thank B Joseph for his support during high pressure XRD measurements at the Xpress beamline of Elettra Sincrotrone, Trieste. Financial support by the Department of Science and Technology (DST) of the Government of India is also gratefully acknowledged.
Publisher Copyright:
© 2023, Indian Academy of Sciences.
PY - 2023/9
Y1 - 2023/9
N2 - Pyrochlore iridate (Eu 2 Ir 2 O 7) shows an interesting metallic phase, termed as incoherent metal, above the metal–insulator transition temperature, with high resistivity and positive temperature coefficient of resistivity (TCR). On increasing the pressure, there is a crossover at pressure P* to a coherent metal phase with positive TCR. We have investigated this crossover using high-pressure Raman spectroscopy and X-ray diffraction for a series of samples (Eu 1-x Bi x) 2 Ir 2 O 7 (x = 0, 0.02, 0.035 and 0.1) up to ∼ 20 GPa. X-ray diffraction data show a clear change in the pressure dependence of Ir–Ir bond distance at P*. The line width of the A 1g phonon shows an anomalous decrease with pressure up to P*, without significant change in the line width of the other three Raman modes with symmetries T2g1 , Eg and T2g2 . We attribute these results to the decreasing contribution of electron–phonon coupling in the incoherent metal till P*.
AB - Pyrochlore iridate (Eu 2 Ir 2 O 7) shows an interesting metallic phase, termed as incoherent metal, above the metal–insulator transition temperature, with high resistivity and positive temperature coefficient of resistivity (TCR). On increasing the pressure, there is a crossover at pressure P* to a coherent metal phase with positive TCR. We have investigated this crossover using high-pressure Raman spectroscopy and X-ray diffraction for a series of samples (Eu 1-x Bi x) 2 Ir 2 O 7 (x = 0, 0.02, 0.035 and 0.1) up to ∼ 20 GPa. X-ray diffraction data show a clear change in the pressure dependence of Ir–Ir bond distance at P*. The line width of the A 1g phonon shows an anomalous decrease with pressure up to P*, without significant change in the line width of the other three Raman modes with symmetries T2g1 , Eg and T2g2 . We attribute these results to the decreasing contribution of electron–phonon coupling in the incoherent metal till P*.
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U2 - 10.1007/s12043-023-02620-2
DO - 10.1007/s12043-023-02620-2
M3 - Article
AN - SCOPUS:85169540179
SN - 0304-4289
VL - 97
JO - Pramana - Journal of Physics
JF - Pramana - Journal of Physics
IS - 3
M1 - 138
ER -