77 research outputs found
Magnetic Instability of Pr3Ru4Sn13
We report on the quantum criticality of PrRuSn revealed by our
new material research. PrRuSn has been synthesized by flux
growth and characterized by single X-ray, powder X-ray, and powder neutron
diffraction measurements. The compound adopts a YbRhSn-type
structure with a cubic Pmn. From the magnetization at 1 T, the
effective magnetic moment was estimated to be 3.58 per Pr,
suggesting that the magnetism is mainly contributed by Pr ions. The
specific heat and magnetization show an anomaly at ~ K owing to
the phase transition. The muon spin rotation and relaxation (SR) time
spectra exhibit clear oscillations below . This suggests that the phase is
magnetically ordered. The volume fraction of the magnetic phase estimated from
the initial asymmetry is around ten percent. In addition, spin fluctuations
were observed at low temperatures. These results provide microscopic evidence
that the material is closest to the antiferromagnetically quantum critical
point with a partial order among PrSn ( Co, Ru, Rh).Comment: 14 pages, 4 figures, accepted for publication in J. Phys. Soc. Jp
The Role of Dorsal Raphe Serotonin Neurons in the Balance between Reward and Aversion
Background: Reward processing is fundamental for animals to survive and reproduce. Many studies have shown the importance of dorsal raphe nucleus (DRN) serotonin (5-HT) neurons in this process, but the strongly correlative link between the activity of DRN 5-HT neurons and rewarding/aversive potency is under debate. Our primary objective was to reveal this link using two different strategies to transduce DRN 5-HT neurons. Methods: For transduction of 5-HT neurons in wildtype mice, adeno-associated virus (AAV) bearing the mouse tryptophan hydroxylase 2 (TPH2) gene promoter was used. For transduction in Tph2-tTA transgenic mice, AAVs bearing the tTA-dependent TetO enhancer were used. To manipulate the activity of 5-HT neurons, optogenetic actuators (CheRiff, eArchT) were expressed by AAVs. For measurement of rewarding/aversive potency, we performed a nose-poke self-stimulation test and conditioned place preference (CPP) test. Results: We found that stimulation of DRN 5-HT neurons and their projections to the ventral tegmental area (VTA) increased the number of nose-pokes in self-stimulation test and CPP scores in both targeting methods. Concomitantly, CPP scores were decreased by inhibition of DRN 5-HT neurons and their projections to VTA. Conclusion: Our findings indicate that the activity of DRN 5-HT neurons projecting to the VTA is a key modulator of balance between reward and aversion
Coupled spin-charge-phonon fluctuation in the all-in/all-out antiferromagnet Cd2Os2O7
We report on a spin-charge fluctuation in the all-in/all-out pyrochlore magnet Cd2Os2O7, where the spin fluctuation is driven by the conduction of thermally excited electrons/holes and associated fluctuation of Os valence. The fluctuation exhibits an activation energy significantly greater than the spin-charge excitation gap and a peculiar frequency range of 10(6)-10(10) s(-1). These features are attributed to the hopping motion of carriers as small polarons in the insulating phase, where the polaron state is presumably induced by the magnetoelastic coupling via the strong spin-orbit interaction. Such a coupled spin-charge-phonon fluctuation manifests as a part of the metal-insulator transition that is extended over a wide temperature range due to the modest electron correlation comparable with other interactions characteristic for 5d-subshell systems
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