We aim to rationalize the heating mechanisms and the corresponding structure evolution at high temperature in responsive nanocomposites made of a thermoplastic elastomer (TPE) filled with 90 nm diameter iron nanoparticles (Fe NP) submitted to a high frequency magnetic field (f=855 kHz). While at low temperature, the heat comes from hysteresis losses generated by Weiss domains walls motion, the melting of the TPE hard phase triggers an additional heating mechanism originating from mechanical friction between the NP and the polymer, leading ultimately to NP alignment. Specifically, we want to observe this structural reorganization by characterizing the static structure through USAXS and NP mobility through XPCS. Regarding the latter, our main goal is to decorrelate the impact of temperature and magnetic field on NP dynamics by measuring their characteristic time and length scales under different experimental conditions.