Jin NAKAMURA (中村 仁)

There is a growing interest in using pulsed high magnetic field as a controlling parameter of physical phenomena in various scientific disciplines, such as condensed matter physics, particle physics, plasma physics, chemistry, and biological studies. We devised a concise and portable pulsed magnetic field generator that produces a 40 T field with a pulse duration of 2 ms. It is assembled using only off-the-shelf components and a homemade coil that leverages small computers, Raspberry Pi, and Python codes. It allows for straightforward modification for general purposes. As working examples, we show representative applications in condensed matter experiments of magnetoresistance, magnetization, and magnetostriction measurements for graphite, NdNi2P2, and NdCo2P2, respectively, with the maximum magnetic field of 41 T and the lowest temperature of 4.2 K.

Aluminum-doped diamond samples were synthesized using the conventional microwave plasma chemical vapor deposition method. The electronic structures were measured using an electron probe microanalyzer and by X-ray photoelectron spectroscopy. The area intensity of the partial profile of Al-3p near the Fermi level increased with increasing aluminum concentration in the sample. The partial profile of Al-3p resembles that of C-2p at high aluminum concentrations, which suggests strong hybridization between Al-3p and C-2p. Additionally, the temperature dependence of the electric resistance yields an activation energy of 8.2 meV at room temperature. The present results suggest the metal–insulator transition of aluminum-doped diamond, similar to that of boron-doped diamond. However, with increasing aluminum concentration, a considerable amount of carriers is not doped to C-2p orbitals in aluminum-doped diamond. The present results indicate that superconductivity in aluminum-doped diamond with the same mechanism as that in boron-doped diamond does not occur.