Figure 3
From: Superconductivity at 44 K in K intercalated FeSe system with excess Fe
(a) Upper: X-ray diffraction pattern of the crystal containing both 30 K and 44 K SC phases. Lower: X-ray diffraction pattern of the crystal with only a 30 K phase. (b) SEM image of the crystal with 44 K SC phase. Dashed blue line indicates the border of Region I, in which EDX gives K:Fe:Se ratio of 0.9:2.17:2. The rest of the area is labeled as Region II, in which K:Fe:Se ratio is 0.8:1.7:2. The light green ellipse represents the laser spot in Raman measurements. (c) Comparison of Raman spectra. Red and blue lines show the spectra collected in Region I+II and in Region II alone, respectively. And the black one comes from the crystal with only a 30 K SC transition. The dashed lines mark the modes only contributed by Region I.
