Al³⁺ and Cr³⁺-substituted garnet Y₃Fe_5-xM_xO₁₂ (M=Al and Cr, x = 0.5 and 1.0) was prepared using a sol-gel method. Mössbauer spectra of Y₃Fe_5-xM_xO₁₂ were taken at various absorber temperatures ranging from 12 to 700 K. As the temperature increased up to Néel temperature, a line broadening of the Mössbauer spectra was observed. Al ions prefer to occupy tetrahedral-sites. The octahedral occupied Fe³⁺ ions are linked to six tetrahedral sites containing a statistical distribution of Fe³⁺ and Al³⁺ ions. In this way, seven nonequivalent octahedral sites are expected. The probability for a Fe³⁺ ion with n nearest-neighbor sites occupied by Fe ions becomes P(n,y) = ₆C_nyⁿ(1-y)^6-n, where y is the iron concentration in tetrahedral (T_d) site. On the contrary, Cr ions prefer to occupy octahedral-sites. So, five nonequivalent tetrahedral sites are expected. It results from the distribution (₄C_n) of Fe³⁺ and Cr³⁺ at octahedral site.

Recently, Fe-rich alloys with ThMn₁₂ structure have attracted much attention as next generation permanent magnet materials. Among them, Sm(Fe_0.8Co_0.2)₁₁Ti alloy shows good magnetic properties, however the low coercivity problem is still to be solved. In order to improve the coercivity, Sm(Fe_0.8Co_0.2)₁₁Ti bulk samples were prepared by adding non-magnetic Sm₇Cu₃ powders (0, 5, and 10 wt%). The crystallographic and magnetic properties of Sm(Fe_0.8Co_0.2)₁₁Ti added Sm₇Cu₃ have been investigated by using X-ray diffractometer (XRD), scaning electron microscope (SEM), and vibrating sample magnetometer (VSM). The phase identity and volume fraction of Sm(Fe_0.8Co_0.2)₁₁Ti powders were determined by using Rietveld refinement. The phase distribution of grains and grain boundaries was analyzed by using SEM. With increasing Sm₇Cu₃ content, the value of saturation magnetization of Sm(Fe_0.8Co_0.2)₁₁Ti bulk samples decreased, while their coercivity increased by about 67% with an addition of a non-magnetic phase.

Magnetocaloric effect is observed for magnetic materials under external magnetic fields due to reduced magnetic entropy by being aligned along the applied field direction. Although it is discovered about 140 years ago, there are still many things to be explored. Here, we introduce basic concepts of magnetocaloric effect in terms of its relation with phase transition and thermodynamics. Various magnetocaloric materials are introduced with recent research trend to control structural/magnetic properties of those materials. Magnetocaloric effect for nanoparticles at cryogenic temperatures are introduced. Lastly, existence of magnetocaloric effect even on ultrafast fs- and ps timescale is discussed.

Spin diffusion theory is widely used to interpret experimental results in the field of spintronics. In this paper, we overview the detailed derivation of spin diffusion equation with emphasizing two main assumptions. We discuss possible misinterpretations when applying the spin diffusion equation to spin-orbit torque experiment, where two assumptions of the spin diffusion theory are not applicable in general.

The ultrashort strain pulse is a picosecond pure mechanical stress without thermal energy, hence it has been actively utilized for the efficient control of magnetization as new type of an excitation source. In the main body organized into two parts, first I briefly described how to generate and measure the ultrafast strain pulses. In the second part, I introduced the current research for magnetization dynamics excited by various types of ultrashort strain pulses. In closing, the prospects for ultrashort strain pulses are presented in the viewpoint of ultrafast nonthermal phase transition for various materials beyond ferromagnetic systems.

Mines have been used to protect army from enemy with cost effectively. In opposite site, quick detection and remove of mines are very important for movement of armed force. Measure and remove of UXO (UneXploded Ordnance) is one of very important problems for safety of peoples living that area after war. To countermeasure mine and UXO, EMI (ElectroMagnetic Impedance), EMI (ElectroMagnetic Induction), Magnetometer, and GPR (Ground Penetrating Radar) methods have been used. In this work, we introduced magnetic field measuring method to find location of mine and UXO because they are made by iron steel and earth magnetic field is distorted by them. The conditions of magnetometers and research trends, which are applicable to unmanned vehicle such as UGV, UAV, USV, and UUV are introduced.