Magnetic Polaronic Exciton in A‐Type 2D van der Waals Bulk Material CrSBr

ABSTRACT Two‐dimensional van der Waals magnetic semiconductors offer unprecedented opportunities to explore coupled magnetic and excitonic phenomena. Through femtosecond transient absorption spectroscopy and density functional theory calculations, we identify the charge‐transfer band edge in CrSBr near 500 nm (2.48 eV) and correlate distinct photoluminescence (PL) channels with Cr 3+ coordination environments. Temperature‐dependent measurements reveal that 720 nm emission (PL 1 ) persists across all temperatures, consistent with isolated Cr 3+ centers; ∼920 nm emission (PL 2 ) intensifies near the ferromagnetic (FM) transition (140 K); and 990 nm emission (PL 3 ) appears only in thick samples below the antiferromagnetic (AFM) transition (132 K). Under strong perpendicular magnetic fields with 488 nm excitation, we observe a dark‐state exciton at ∼850 nm, with anticorrelated intensity variations between PL 1 /dark‐state and PL 2 /PL 3 , demonstrating field‐tuned energy redistribution. These findings establish magnetic polaronic excitons in van der Waals semiconductors and enable manipulation of excitonic properties through magnetic order control.