SPIN

This paper reviews issues of biological effects and safety aspects of the electromagnetic fields related to both Magnetic Resonance Imaging (MRI) and Transcranial Magnetic Stimulation (TMS) as a diagnostic technique. The noninvasive character of these diagnostic techniques is based on the utilization of the electromagnetic fields such as the static magnetic field, time-varying magnetic field, and radiofrequency electromagnetic field. Following the short view of the history and the principle of these noninvasive techniques, we review the biological effects of the electromagnetic fields, the health effects and safety issues related to MRI/TMS environments. Through a discussion of biological and health effects, it shows briefly guidelines which provide a consideration in human risk for both patients and medical staff. Finally, safety issues related to MRI/TMS are discussed with the highlighting of the guideline such as the International Commission on NonIonizing Radiation Protection (ICNIRP) and EMF Directive (Directve2013/35/EU) of European Union.

Spin pumping efficiency (SPE) in a ferromagnetic (FM)/Pt system relies on the effective magnetization damping of FM layer and the interface spin mixing conductance. However, there are very few studies on the influence of magnetic anisotropy of FM material on SPE. In this study, the spin pumping induced spin voltage $V_{\mathrm{\text{ISHE}}}$ in Fe₃O₄(58.9nm)/Pt(5.5nm) is investigated in two different orientations of the external magnetic field, one parallel and other perpendicular to the in-plane easy axis of Fe₃O₄. The value of $V_{\mathrm{\text{ISHE}}}$ with the magnetic field along the easy axis is 38% higher compared with that along the hard axis. The possible origin of this enhancement is investigated based on the model of ferromagnetic resonance induced spin pumping.

Some experimental research works report on the superb magnetoresistance properties of magnetically contacted gold nanowires. With the intention of trying to understand the spin-dependent transport mechanism of these structures, in this work we have used first-principles density functional theory methods to investigate effects of interface structure on the spintronic characteristics of Au nanowires. Monatomic chains of gold are sandwiched between two ferromagnetic electrodes of Fe and by substituting the interfacial Fe atoms with some other transition metal elements (including Cr, Mn, Co and Ni) the occurrence of possible enhancement in the electronic conductance and magnetoresistance characteristics of the device are investigated. It is observed that replacing the interfacial atoms with Ni raises the junction’s magnetoresistance ratio to as high as 2000%.

A systematic investigation on magnetism and spin-resolved electronic properties in double perovskite Ca₂CoMoO₆ compound was performed by using the full-potential augmented plane wave plus local orbitals (APW$+lo$) method within the generalized gradient approximation (GGA-PBE) and GGA-PBE$+U$ scheme. The stability of monoclinic phase ($P{2}_1∕n$ #14) relative to the tetragonal ($I4∕m$#87) and cubic ($Fm\bar{3}m$ #225) phase is evaluated. We investigate the effect of Hubbard parameter $U$on the ground-state structural and electronic properties of Ca₂CoMoO₆ compound. We found that the ferromagnetic ground state is the most stable magnetic configuration. The calculated spin-polarized band structures and densities of states indicate that the Ca₂CoMoO₆ compound is half-metallic (HM) and half-semiconductor (HSC) ferromagnetic (FM) semiconductor with a total magnetic moment of 6.0 using GGA-PBE and GGA-PBE$+U$, respectively. The Hubbard $U$ parameter provides better description of the electronic structure. Using the Vampire code, an estimation of exchange couplings and magnetic Curie temperature is calculated. Further, our results regarding the magnetic properties of this compound reveal their ferromagnetic nature. The GGA-PBE$+U$ approach provides better band gap results as compared to GGA-PBE approximation. These results imply that Ca₂CoMoO₆ could be a promising magnetic semiconductor for application in spintronic devices.

In this study, we present the calculated structural, electronic and magnetic properties of mixed Heusler alloys (Ni${}_{1-x}$Co${}_x{)}_2$MnSn. Using ab initio calculations with the full-potential augmented plane-wave method (FP-LAPW), we evaluated the various possible configurations of Ni and Co sites in the (Ni${}_{1-x}$Co${}_x{)}_2$MnSn crystallographic lattice. The lowest energy configuration is determined based on energetic considerations. The calculated equilibrium lattice parameters and magnetic moments are in a reasonable agreement with available experimental data. Of interest, we found that the change of total magnetic moment can be interpreted as a linear variation of the magnetic moment of manganese and cobalt atoms.

A cylindrical ferrimagnetic magnetic nanowire system of core and shell layers has been investigated using Monte Carlo simulation. Critical temperature is obtained for different values of exchange couplings at the core–shell interface, at shell–shell and core–core. The total magnetization has been the determinate for different values of crystal field. Hysteresis loop, coercive field and remanent magnetization of a core and shell layers are obtained using the Monte Carlo simulation. A number of characteristic behaviors are found, such as the occurrence of single and triple hysteresis loops for appropriate values of crystal field, temperatures values and exchange interaction values.