title: External magnetic field dependent shift of superparamagnetic blocking temperature due to core/surface disordered spin interactions.
abstract: Although the blocking temperature of superparamagnetic nanoparticles (SPNPs) is crucial for various spintronics and biomedical applications, the precise determination of the blocking temperature is still not clear. Here, we present 'intrinsic' and 'extrinsic' characteristics of the blocking temperature in SPNP systems. In zero-field-cooled/field-cooled (ZFC-FC) curves, there was no shift of 'intrinsic blocking temperature' at different applied external (excitation) magnetic fields. However, 'extrinsic blocking temperature' shift is clearly dependent on the external (excitation) magnetic field. According to our newly proposed physical model, the 'intermediate spin layer' located between the core and surface disordered spin layers is primarily responsible for the physical nature of the shift of extrinsic blocking temperature. Our new findings offer possibilities for characterizing the thermally induced physical properties of SPNPs. Furthermore, these findings provide a new empirical approach to indirectly estimate the qualitative degree of the disordered surface spin status in SPNPs.
authors.affiliation: Nanobiomagnetics and Bioelectronics Laboratory (NBL), Department of Electrical Engineering, University of South Carolina, Columbia, SC 29208, United States. P&B Nano Laboratory, Advanced Institutes of Convergence Technology (AICT), Yeongtong-gu, Suwon-si, Gyeonggi-do, 443-270, Republic of Korea.
authors.forename: Kwan
authors.initials: K
authors.lastname: Lee
authors.forename: Jung-Tak
authors.initials: JT
authors.lastname: Jang
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nakano
authors.forename: Shigeki
authors.initials: S
authors.lastname: Nakagawa
authors.forename: Sun Ha
authors.initials: SH
authors.lastname: Paek
authors.forename: Seongtae
authors.initials: S
authors.lastname: Bae