Figure 1. Observation of electron-phonon coupling in Bi₂Se₃.

(a) Surface state dispersions along (left panel) and (right panel) directions. The inset shows the Fermi surface of Bi₂Se₃. (b) Momentum distribution curves (MDCs) of the surface state dispersion along . Red line and blue line indicate the MDCs at the Dirac point (E_D) and the Fermi level (E_F), respectively. (c) Dispersion and effective electron self-energy of surface state band along direction. The left panel shows the measured dispersion (red circles) obtained from MDC fitting. The blue dotted line represents an empirical bare band that is a straight line connecting two points in the measured dispersion, one at E_F and the other at 100 meV binding energy. The right panel shows the effective real part of the electron self-energy, ReΣ(k, ω) (black circles), and imaginary part of the electron self-energy, ImΣ(k, ω) (blue squares). The red dashed line is a linear fit to the low-energy region of ReΣ(k, ω). Blue arrows indicate the characteristic energy scale of the electron-phonon coupling. (d)Dispersion and effective electron self-energy of surface state band along direction.