arXiv subjects

H. Osawa

Publications and source records attributed to H. Osawa.

2 recordsLinked to original sources

arXiv2022

Suppression of atomic displacive excitation in photo-induced A$_{\mathrm{1g}}$ phonon mode of bismuth unveiled by low-temperature time-resolved x-ray diffraction

An ultrafast atomic motion of a photo-induced coherent phonon of bismuth at low temperatures was directly observed with time-resolved x-ray diffraction. A cryostat with a window that is transparent to both optical lasers and x-rays enabled versatile diffraction measurements in a wide temperature range including below 10 K. It is found that an atomic displacement in a fully symmetric A$_{\mathrm{1g}}$ phonon mode is suppressed at low temperatures. This result indicates the displacive excitation process is suppressed in the phonon generation with decreasing temperature.

cond-mat.mtrl-sci↗

arXiv2022

Following enhanced Sm spin projection in Gd$_x$Sm$_{1-x}$N

The rare-earth nitrides form a series of structurally simple $intrinsic$ ferromagnetic semiconductors, a rare class of both fundamental interest and application potential. Within the series there is a wide range of magnetic properties relating to the spin/orbit contributions to the ferromagnetic ground states. We report an x-ray magnetic circular dichroism investigation of the spin/orbit magnetic dipole alignments of Sm and Gd ions in epitaxial Gd$_x$Sm$_{1-x}$N films. The Sm spin-alignment expectation value $\langle S_{z} \rangle$ is seen to be strengthened by the Gd/Sm exchange interaction, providing guidance concerning the composition for an angular momentum compensation point (where the volume-averaged total angular momentum of a film is zero).

cond-mat.mtrl-sci↗