Cr 1/4 NbSe 2 ‐Single Crystal Growth and Evolution of Antiferromagnetic Correlated States

ABSTRACT Transition‐metal dichalcogenides provide a versatile platform for the intercalation of magnetic ions in their van der Waals gaps, enabling tuning of correlated electronic and magnetic states. Despite extensive studies on sulfide‐based systems, Cr x NbSe 2 remains poorly understood due to scarcity of single‐crystals and uncertainties in structural analyses leading to contradictory reports on its magnetic behavior. Here, high‐quality single crystals of Cr 1/4 NbSe 2 via chemical vapor transport were synthesized, along with comprehensive investigation of chemical, structural, electronic, optical, electrical, and magnetic properties, supported by density‐functional theory calculations, presented for the first time. Single crystal x‐ray diffraction, scanning transmission electron microscopy, and selected area electron diffraction reveal ordered Cr intercalation forming a centrosymmetric 2 × 2 superlattice with hexagonal symmetry P 6 3 / mmc . Optical reflectivity indicates an enhanced electron scattering rate. DFT calculations predict antiferromagnetic ground state induced by Cr intercalation. Consistently, SQUID magnetometry and specific heat measurements hint a correlated antiferromagnetic state at T N ≈ 107 K, while resistivity measurements show metallic transport, with no signatures of superconductivity. Electron spin resonance suggests weak internal field which possibly arise from subtle magnetic anisotropy, undetectable in angle‐resolved magnetometry. These findings resolve longstanding inconsistencies and establish Cr 1/4 NbSe 2 as a benchmark vdW antiferromagnet for next‐generation spintronic and quantum materials.