Room-Temperature Magnetic Enhancement due to Spin-Polarized Charge Transfer in Carbon-Encapsulated Magnetite Nanoparticles
Jiann-Shing Lee1, Wen-Bin Wu1, Jiunn Chen1*, Chi Liang Chen2, Hung-Wei Kuo2, Chun - Rong Lin1, Hong-Ji Lin2, Chien-Te Chen2
1Department of Physics, National Pingtung University, Pingtung, Taiwan
2National synchrotron radiation research center, Hsinchu, Taiwan
* Presenter:Jiunn Chen,
The origin of room temperature magnetic enhancement (~24%) in Fe3O4@carbon nanocomposite were uncovered in this work. Enhanced room-temperature magnetism can dramatically increase the contrast of MRI, reduce the concentration of magnetic particles required for cell separation, and allow drug delivery with much lower magnetic field gradients. Calculations based on Generalized Gradient Approximation employing Hubber-U correction (GGA+U) consist of the ionic picture hypothesis, which links the magnetic enhancement to the spin-polarized electronic charge transfer to Fe ions in the tetrahedral site of Fe3O4. First-principle calculations in conjunction with synchrotron radiation spectroscopy indicated that the polarized charge transfer into tetrahedral site of Fe3O4 give rise to the magnetic enhancement.

Keywords: first-principle calculation, synchrotron radiation, magnetite, magnetic enhancement