Potential for Improvement of Gut Microbiota Deterioration Caused by a High-fat, High-sucrose Diet through Administration of Acylated Steryl-ß-glycosides.

Consumption of a high-fat diet (HFD) is associated with an increased risk of metabolic diseases, cancer, and neurological disorders, which are major global health concerns. In the present study, mice were fed a HFD containing 40% fat and 0.5% or 1.0% acylated steryl-ß-glucosides (ASG) and their gut microbiota was compared to that of mice fed with a low-fat diet (LFD). After 55 d, the epididymal fat weight was higher in the HFD and ASG groups than in the LFD group; however, the epididymal fat weight was lower in the ASG group than in the HFD group. The abundance of gut microbiota increased with HFD in obese micespecific Bacillota, but decreased when ASG was added to the HFD. The number of intestinal bacteria involved in the production of carcinogenic secondary bile acids was increased by the consumption of HFD, but decreased by the addition of ASG to HSD. This finding may indicate the gut bacteria-mediated health benefits of ASG.

Theory of Emergent Inductance with Spin-Orbit Coupling Effects.

We extend the theory of emergent inductance, which has recently been discovered in spiral magnets, to arbitrary magnetic textures by taking into account spin-orbit couplings arising in the absence of spatial inversion symmetry. We propose a new concept of spin-orbit emergent inductance, which can be formulated as originating from a dynamical Aharonov-Casher phase of an electron in ferromagnets. The spin-orbit emergent inductance universally arises in the coexistence of magnetism and the spin-orbit couplings, even with spatially uniform magnetization, allowing its stable operation in wide ranges of temperature and frequency. Revisiting the widely studied systems involving ferromagnets with spatial inversion asymmetry, with the new perspective offered by our work, will lead to opening a new paradigm in the study of spin-orbit physics and the spintronics-based power management in ultrawideband frequency range.

Chiral-spin rotation of non-collinear antiferromagnet by spin-orbit torque.

Electrical manipulation of magnetic materials by current-induced spin torque constitutes the basis of spintronics. Here, we show an unconventional response to spin-orbit torque of a non-collinear antiferromagnet Mn3Sn, which has attracted attention owing to its large anomalous Hall effect despite a vanishingly small net magnetization. In epitaxial heavy-metal/Mn3Sn heterostructures, we observe a characteristic fluctuation of the Hall resistance under the application of electric current. This observation is explained by a rotation of the chiral-spin structure of Mn3Sn driven by spin-orbit torque. We find that the variation of the magnitude of anomalous Hall effect fluctuation with sample size correlates with the number of magnetic domains in the Mn3Sn layer. In addition, the dependence of the critical current on Mn3Sn layer thickness reveals that spin-orbit torque generated by small current densities, below 20 MA cm-2, effectively acts on the chiral-spin structure even in Mn3Sn layers that are thicker than 20 nm. The results provide additional pathways for electrical manipulation of magnetic materials.

Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient.

Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter ß that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient.

Time-domain observation of the spinmotive force in permalloy nanowires.

The spinmotive force associated with a moving domain wall is observed directly in Permalloy nanowires using real time voltage measurements with proper subtraction of the electromotive force. Whereas the wall velocity exhibits nonlinear dependence on magnetic field, the generated voltage increases linearly with the field. We show that the sign of the voltage reverses when the wall propagation direction is altered. Numerical simulations explain quantitatively these features of spinmotive force and indicate that it scales with the field even in a field range where the wall motion is no longer associated with periodic angular rotation of the wall magnetization.