TY - JOUR

T1 - Correlation of exchange coupling and dipolar interactions with magnetization reversal in strontium ferrite/nickel-doped cobalt ferrite composites

AU - Shabbir, Saqib

AU - Alam, Ayub

AU - Iqbal, Muhammad Tayyab

AU - Ullah, Aneeb

AU - Khan, Gul Wali

AU - Aqib, Muhammad

AU - Shabbir, Sania

PY - 2026/6/22

Y1 - 2026/6/22

N2 - This study presents a comprehensive investigation of hard-soft magnetic composites [SrFe12O19 (SFO) and Ni0.1Co0.9Fe2O4 (NCFO)] synthesized via mechanical ball milling. The composites were analyzed to understand the interplay between exchange coupling, dipolar interactions, and high-field magnetization behavior. X-ray diffraction confirmed the coexistence of hexagonal SFO and cubic spinel NCFO phases without any secondary phase. A steady decrease in crystallite size and a slight change in lattice suggest effective strain accommodation and interfacial interaction. SEM analysis revealed increased particle agglomeration with increasing NCFO content. Magnetic measurements confirmed single-step hysteresis loops, confirming exchange-coupled characteristics. The saturation magnetization decreased with increasing NCFO content, while coercivity was moderately reduced yet remained high due to dominant hard-phase anisotropy. Optimal exchange coupling was observed in the 10 to 20 wt% composites, beyond which partial magnetic decoupling occurred. Law of Approach to Saturation (LAS) analysis revealed increasing defect-related contributions (α1) and high-field susceptibility (χhf), indicating enhanced interfacial disorder and spin canting. At the same time, magneto-crystalline anisotropy (α2) remained relatively stable. IRM-DCD and ΔM analyses confirmed a transition from dipolar-dominated interactions to mixed exchange dipolar interactions with increased soft-phase concentration. Thermo-magnetic analysis confirmed distinct Curie temperatures of both phases, validating phase stability. Singular Point Detection (SPD) analysis revealed nearly constant anisotropy fields, suggesting that intrinsic anisotropy depends only on hard-phase. This work lies in the combined application of LAS, IRM-DCD, and SPD techniques to establish a direct correlation between microstructure, exchange coupling, and magnetization reversal behavior. Overall, the study reveals that controlled soft-phase incorporation effectively tailors magnetic interactions and reversal mechanisms, making these composites promising for high-frequency and microwave applications.

AB - This study presents a comprehensive investigation of hard-soft magnetic composites [SrFe12O19 (SFO) and Ni0.1Co0.9Fe2O4 (NCFO)] synthesized via mechanical ball milling. The composites were analyzed to understand the interplay between exchange coupling, dipolar interactions, and high-field magnetization behavior. X-ray diffraction confirmed the coexistence of hexagonal SFO and cubic spinel NCFO phases without any secondary phase. A steady decrease in crystallite size and a slight change in lattice suggest effective strain accommodation and interfacial interaction. SEM analysis revealed increased particle agglomeration with increasing NCFO content. Magnetic measurements confirmed single-step hysteresis loops, confirming exchange-coupled characteristics. The saturation magnetization decreased with increasing NCFO content, while coercivity was moderately reduced yet remained high due to dominant hard-phase anisotropy. Optimal exchange coupling was observed in the 10 to 20 wt% composites, beyond which partial magnetic decoupling occurred. Law of Approach to Saturation (LAS) analysis revealed increasing defect-related contributions (α1) and high-field susceptibility (χhf), indicating enhanced interfacial disorder and spin canting. At the same time, magneto-crystalline anisotropy (α2) remained relatively stable. IRM-DCD and ΔM analyses confirmed a transition from dipolar-dominated interactions to mixed exchange dipolar interactions with increased soft-phase concentration. Thermo-magnetic analysis confirmed distinct Curie temperatures of both phases, validating phase stability. Singular Point Detection (SPD) analysis revealed nearly constant anisotropy fields, suggesting that intrinsic anisotropy depends only on hard-phase. This work lies in the combined application of LAS, IRM-DCD, and SPD techniques to establish a direct correlation between microstructure, exchange coupling, and magnetization reversal behavior. Overall, the study reveals that controlled soft-phase incorporation effectively tailors magnetic interactions and reversal mechanisms, making these composites promising for high-frequency and microwave applications.

KW - Exchange-spring magnets

KW - LAS

KW - Magneto-crystalline anisotropy

KW - Thermo-magnetic behavior

KW - XRD

UR - https://www.scopus.com/pages/publications/105042678476

UR - https://www.mendeley.com/catalogue/e2d7f129-7e97-387d-a0db-72448d8b02bc/

U2 - 10.1016/j.ceramint.2026.06.267

DO - 10.1016/j.ceramint.2026.06.267

M3 - Article

JO - Ceramics International

JF - Ceramics International

SN - 0272-8842

ER -