In this work, we showed the experimental methodology for the precise characterization of the spin thermoelectric device of longitudinal spin Seebeck geometry, including heater design, temperature calibration, and the estimation of the spin-thermoelectric energy conversion. In particular, the developed on-chip heater design allows nominal heat dissipation due to direct contact between the device and heat source, and its simultaneous use for temperature sensor based-on temperature dependent resistance provides precise calibration for the thermal gradient applied on thin magnetic layer.

AlFe₂B₂ is one of good candidates for the magnetic refrigerator with the magnetic cooling effect. In this study, we investigated the change of magnetocaloric properties by doping 1.5% and 5.0% of B in AlFe₂B₂. Structural phase analysis through X-ray diffraction was carried out to find the optimal conditions for the synthesis of AlFe₂B₂ by arc-melting, and then analyzed AlFe₂B₂ phase after post-treatment, such as acid-treatment and annealing. As a result of the structural phase analysis, the presence or absence of FeB impurities was determined according to the amount of doping in the post-treated AlFe₂B₂. Each sample was measured using Magnetic Properties Measurement System (MPMS) for magnetic properties. The magnetization and saturation magnetization in terms of temperature were measured, and the difference in magnetization value was observed according to the amount of B doping. The magnetic entropy change (-ΔS) was calculated from the measured M-H data. -ΔS at 2 T has 2.01 J/kg∙K and 2.24 J/kg∙K for boron 1.5% and 5.0% doped samples, respectively. The difference between the magnetization values and -ΔS was due to the amount of FeB impurities produced by B doping.

As a device that measures a fine magnetic field to be used as a biosensor, a simple multilayered cross-shaped current and voltage terminals are formed. The sensitivity of planar Hall voltage sensitivity (SPHV) were obtained from the planar Hall voltage (PHV) curve, which was measured by applying an external magnetic field perpendicular to the magnetization easy axis. The PHV curve for the NiFe(6 nm)/Ta(20 nm)/NiFe(6 nm) multilayer changed linearly in the region of ±0.9 Oe, and the SPHV was 500 μV/Oe. In particular, as the increased sensing current from 1.0 mA to 40 mA, the SPHV was from 2.0 mV/Oe to 398 μV/Oe. These results suggested the possibility of developing a PHR biosensor with high sensitivity even with a multilayer structure formed of a bottom Ta layer and a ferromagnetic NiFe layer.

The difference of proliferation rates between human liver cancer cells and normal liver cells stimulated by alternative magnetic field at the frequency of 1.5 kHz and the intensity of 0.5 mT during 48 hours in incubator were investigated. The proliferation rates of liver cancer cells stimulated by the magnetic field decreased up to 79%, but the rates of normal liver cells did not change in spite of the magnetic field stimulation. It is assumed that the alternative magnetic stimulation on the living cells can influence to the proliferation rates of liver cancer cells. In order to know the influence of ion channel on magnetic field in liver cell membrane, we should study to the frequency dependence of alternative magnetic field.

We investigated the electronic and magnetic properties for a diluted magnetic semiconductor of 3d-metal Mn-doped chalcopyrite (CH) AlAs, GaAs, and AlGaAs₂ semiconductors by using the first-principle calculations. The CH-AlGaAs₂:Mn without the defects exhibits the ferromagnetic and half-metallic states. For the system of CH-Al(Ga,Mn)As₂, the ferromagnetism with high magnetic moment of Mn is induced from the exchange couplings between Mn-3d and As-4p bands. The partially unoccupied majority-spin Mn-3d and As-4p states are induced. Thus the Mn moments couple to holes by an on-site exchange interaction due to the overlap of the hole wave-function with the Mn-3d (or As-4p) electrons. The electronic and magnetic properties for Mn-doped CH-AlAs and CH-GaAs systems were compared with that of CH-Al(Ga,Mn)As₂. It is noticeable that high magnetic moment induces from the characteristics by holes-mediated double-exchange coupling.

Biomedical convergence technology based on magnetic technology has been potential ranges from expensive medical equipment such as MRI and MEG that can be used in large hospitals to laboratory-level equipment such as molecular diagnostic equipment, and simple devices that can be used by individuals such as immunochromatography. Until now, they are active in various fields in the field of disease diagnosis. Diagnosis technology using magnetic sensors and magnetic nanoparticles shows the possibility of developing small, portable equipment with diagnostic capabilities comparable to those of medical equipment used in hospitals. In addition to such disease diagnosis, various studies are being conducted as a next-generation biomedical technology such as manipulation of cell location and remote control of nerve cells. This paper briefly summarizes the previously described studies and introduces recent research trends in molecules(microscopic), cells(mesoscopic), organs and bodies(macroscopic) studies.