Superconductivity of iron chalocogenides is strongly enhanced under applied pressure yet its underlying pairing mechanism remains elusive. Here, we present a quantum oscillations study up to 45 T in the high-T_c phase of tetragonal FeSe_0.82S_0.18 up to 22 kbar. Under applied pressure, the quasi-two-dimensional multi-band Fermi surface expands and the effective masses remain large, whereas the superconductivity displays a threefold enhancement. Comparing with chemical pressure tuning of FeSe_1−xS_x, the Fermi surface expands in a similar manner but the effective masses and T_c are suppressed. These differences may be attributed to the changes in the density of states influenced by the chalcogen height, which could promote stronger spin fluctuations pairing under pressure. Furthermore, our study also reveals unusual scattering and broadening of superconducting transitions in the high-pressure phase, indicating the presence of a complex pairing mechanism.

铁硫族化物的超导性在施加压力下得到强烈增强，但其潜在的配对机制仍然难以捉摸。在这里，我们提出了在高达 22 kbar 的四方 FeSe _0.82 S _0.18 的高 T _c 相中高达 45 T 的量子振荡研究。在施加压力下，准二维多带费米面膨胀，有效质量仍然很大，而超导性则显示出三倍增强。与FeSe _1−x S _x 的化学压力调节相比，费米面以类似的方式膨胀，但有效质量和T _c 受到抑制。这些差异可能归因于受硫族高度影响的态密度的变化，这可能会促进压力下更强的自旋涨落配对。此外，我们的研究还揭示了高压相中超导转变的异常散射和展宽，表明存在复杂的配对机制。