Abnormal thermal conductivity in thin antiferromagnet CrPS4 nanoribbons: Effect of elastic stiffening and magnon–phonon coupling

Thermal management is critical for ensuring the stability and reliability of two-dimensional (2D) magnetic devices. In this manuscript, we report the thermal conductivity measurements of a 2D antiferromagnet CrPS4 with thickness ranging from 34 to 106 nm. We observe a nonmonotonic thickness-dependence driven by the enhanced magnon–phonon coupling and elastic stiffening in thin CrPS4 nanoribbons, competing with the phonon-boundary scattering. More specifically, Young’s modulus increases 5.8-fold as thickness decreases from 76 to 37 nm, while magnon–phonon scattering rate also decreases monotonically. Our measurement further suggests that magnon–phonon scatterings participate in thermal transport up to nearly T ∼ 80 K, far above TN, with thermal conductivity increasing with magnetic field. When T < TN (Néel temperature, 38 K), thermal conductivity exhibits distinct field-dependent behaviors: decreasing in antiferromagnetic phase, unchanged in canted antiferromagnetic phase, and increasing in ferromagnetic phase.