Magnetic Properties of Nd-Fe-B Single Dots Fabricated Using the PLD–LIFT Method

Single-dot Nd–Fe–B micromagnets were fabricated using the pulsed laser deposition–laser-induced forward transfer (PLD-LIFT) technique, and their magnetic properties were systematically examined. Hysteresis measurements with a vibrating sample magnetometer revealed that the coercivity (Hc) was nearly independent of laser power (LP), whereas an increased defocus rate (DF rate) enhancedHcup to 340 kA/m. SEM and cross-sectional STEM analyses revealed that each dot comprises grains ranging from submicron to micrometer scale. Within these grains, an Nd₂Fe₁₄B core is encapsulated by an Fe-rich matrix containing dispersed Nd oxides. The thickness of this Fe-rich outer shell modifies the exchange pathway at the Nd₂Fe₁₄B/Fe interface, giving rise to the characteristic two-step demagnetization. Guided by these observations, a simplified Nd₂Fe₁₄B/α-Fe core–shell model was developed and evaluated through micromagnetic simulations, which successfully reproduced the stepwise reversal and clarified DF's role in suppressing soft-phase connectivity and improving loop squareness. Collectively, these findings identifyDF rateas the dominant processing parameter and provide practical guidelines for tailoring PLD-LIFT Nd–Fe–B micromagnets toward MEMS applications.