Critical Slowing Down of Quadrupole and Hexadecapole Orderings in Iron Pnictide Superconductor

2017/05/25 by Ryosuke Kurihara, Keisuke Mitsumoto, Mitsuhiro Akatsu +5 · 22 citations
Business, Management and Accounting · Materials Science · Physics and Astronomy · #Atomic physics #Condensed matter physics #Corporate Taxation and Avoidance #Degenerate energy levels #Iron-based superconductors research #Lattice (music) #Order (exchange) #Physics #Pnictogen #Quadrupole #Quantum mechanics #Superconductivity #Tetragonal crystal system #cond-mat.str-el #cond-mat.supr-con

paper · pdf · doi:10.7566/jpsj.86.064706

published in Journal of the Physical Society of Japan 86(6), 064706 (Physical Society of Japan)

openalex publication_date 2017/05/25 · arxiv created 2017/05/29 · arxiv updated 2017/05/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/08

Abstract

Ultrasonic measurements have been carried out to investigate the critical dynamics of structural and superconducting transitions due to degenerate orbital bands in iron pnictide compounds with the formula Ba(Fe_1-xCo_x)₂As₂. The attenuation coefficient α_L[110] of the longitudinal ultrasonic wave for (C₁₁+C₁₂+2C₆₆)/2 for x = 0.036 reveals the critical slowing down of the relaxation time around the structural transition at T_s = 65 K, which is caused by ferro-type ordering of the quadrupole O_x'²-y'² coupled to the strain ε_xy. The attenuation coefficient α₆₆ of the transverse ultrasonic wave for C₆₆ for x = 0.071 also exhibits the critical slowing down around the superconducting transition at T_SC = 23 K, which is caused by ferro-type ordering of the hexadecapole H_z^α ( \boldsymbolr_i, \boldsymbolr_j ) = O_x'y'( \boldsymbolr_i ) O_{x'² - y'²}( \boldsymbolr_j ) + O_{x'² - y'²}( \boldsymbolr_i ) O_x'y'( \boldsymbolr_j ) of the bound two-electron state coupled to the rotation ω_xy. It is proposed that the hexadecapole ordering associated with the superconductivity brings about spontaneous rotation of the macroscopic superconducting state with respect to the host tetragonal lattice.

Citations

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