Dipolar field impact on the magnetocaloric effect of Gd nanoelements

We present a theoretical study of the magnetocaloric effect (MCE) in rectangular gadolinium (Gd) nanoelements, focusing on the influence of dipolar fields induced by geometrical confinement. Using a micromagnetic approach, we calculate the isothermal magnetic entropy change, Δ S M ( T , H ) , for nanoelements with different lateral dimensions and thicknesses. Our results show that internal dipolar fields, with magnitudes comparable to or larger than the applied magnetic field, strongly modify both the magnetic configurations and the magnetocaloric response. Thin nanoelements exhibit quasi-uniform magnetization and conventional MCE behavior, reaching up to ∼ 70 % of the bulk entropy change. In contrast, increasing the thickness enhances dipolar interactions, stabilizes vortex configurations, and introduces additional anomalies in Δ S M ( T , H ) associated with geometry-driven magnetic transitions. We demonstrate that the superposition of external and dipolar fields generates an effective internal field that suppresses the field-induced variation of the magnetization, thereby reducing the magnetic entropy change. These findings reveal that the interplay between dipolar interactions and geometrical confinement governs the magnetocaloric behavior of Gd nanoelements and provides a mechanism for tuning thermomagnetic properties at the nanoscale.