Effect of Milling Conditions on the Microstructure and Interphase Exchange Coupling of Nd2Fe14B/α-Fe Nanocomposites

AbstractThe effects of milling conditions on the microstructure and interphase exchange coupling of Nd2Fe14B+10 wt% α-Fe nanocomposites were investigated. The α-Fe crystallite size is critical for obtaining an efficient interphase exchange coupling. The problem of damaging the Nd2Fe14B crystal structure during milling was addressed by using different milling conditions. Nd2Fe14B+ 10 wt% α-Fe powder samples were prepared through mechanical milling for 6h with Ø = 10mm and Ø = 15mm balls respectively. The restoration of the Nd2Fe14B crystal structure after annealing was confirmed by XRD, with a limited growth of α-Fe crystallites. The magnetic behavior was investigated from hysteresis curves and dM/dH vs. H plots. The samples milled with small balls show a good interphase exchange coupling, however, milling with larger diameter balls determined higher coercivities due to the reduced damaging of the Nd2Fe14B crystal structure during milling. The best exchange coupling was obtained for the samples annealed at 750°C for 1.5minutes, with a maximum coercive field of about 0.65 T. The Nd2Fe14B /α-Fe exchange coupling was analyzed as a function of milling and annealing conditions

Microstructure and interphase magnetic coupling in Nd2Fe14B/alpha-Fe nanocomposites obtained by mechanical milling and short time annealing

International audienceThe effects of short time annealing and soft phase pre-milling on the structural and magnetic properties of 6 h milled Nd2Fe14B/10wt% Fe magnetic nanocomposites were investigated. The X-ray diffraction peaks of Nd2Fe14B disappeared after milling due to crystal structure damage, this effect being more pronounced when using pre-milled Fe. After annealing, the characteristic peaks of Nd2Fe14B were restored with a limited growth of the α-Fe crystallites. The best exchange coupling was obtained for the samples which contain unmilled Fe as the soft phase. The maximum coercive field is 0.61 T. The samples containing pre-milled Fe have lower coercive field values, but show a higher remanence. The Nd2Fe14B/α-Fe exchange coupling is analysed

Structural, electronic and magnetic properties of the Mn 50 Al 46 Ni 4 alloy

International audienc

Route towards efficient magnetization reversal driven by voltage control of magnetic anisotropy

International audienceAbstract The voltage controlled magnetic anisotropy (VCMA) becomes a subject of major interest for spintronics due to its promising potential outcome: fast magnetization manipulation in magnetoresistive random access memories with enhanced storage density and very low power consumption. Using a macrospin approach, we carried out a thorough analysis of the role of the VCMA on the magnetization dynamics of nanostructures with out-of-plane magnetic anisotropy. Diagrams of the magnetization switching have been computed depending on the material and experiment parameters (surface anisotropy, Gilbert damping, duration/amplitude of electric and magnetic field pulses) thus allowing predictive sets of parameters for optimum switching experiments. Two characteristic times of the trajectory of the magnetization were analyzed analytically and numerically setting a lower limit for the duration of the pulses. An interesting switching regime has been identified where the precessional reversal of magnetization does not depend on the voltage pulse duration. This represents a promising path for the magnetization control by VCMA with enhanced versatility

Additional file 1: of Polyethylene Glycol-Mediated Synthesis of Cubic Iron Oxide Nanoparticles with High Heating Power

It contains a TEM image of IOMNPs, the magnetic hysteresis at 4 K of IOMNPs, the ZFC-FC curves of IOMNPs, the SAR values of IOMNPs in PEG600 and PEG1000, DLS spectra of IOMNPs, and information related to the XRD and XPS analysis and magnetic properties of IOMNPs. The calibration of the hyperthermia setup and the experimental and theoretical protocols for SAR determination are fully described as well. (DOCX 1448 kb