82 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
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
PROPOSAL OF SINGLE-FLUX-QUANTUM LOGIC DEVICE
A new type of logic gate that can be designed using a nonhysteretic Josephson weak link is proposed. The basic component of the proposed device is a one-junction interferometer, and a logic state is represented by either a zero or a single-flux-quantum. In contrast to the “Parametric Quantron,” this device is designed to operate without a three-phase clock and the dependence of the junction critical current on magnetic field is not used. The switching behavior of the device was simulated by computer and an analytical expression for the switching delay has been obtained
Dimensional reduction by geometrical frustration in a cubic antiferromagnet composed of tetrahedral clusters
Dimensionality is a critical factor in determining the properties of solids and is an apparent built-in character of the crystal structure. However, it can be an emergent and tunable property in geometrically frustrated spin systems. Here, we study the spin dynamics of the tetrahedral cluster antiferromagnet, pharmacosiderite, via muon spin resonance and neutron scattering. We find that the spin correlation exhibits a two-dimensional characteristic despite the isotropic connectivity of tetrahedral clusters made of spin 5/2 Fe3+ ions in the three-dimensional cubic crystal, which we ascribe to two-dimensionalisation by geometrical frustration based on spin wave calculations. Moreover, we suggest that even one-dimensionalisation occurs in the decoupled layers, generating low-energy and one-dimensional excitation modes, causing large spin fluctuation in the classical spin system. Pharmacosiderite facilitates studying the emergence of low-dimensionality and manipulating anisotropic responses arising from the dimensionality using an external magnetic field
Abnormal spermatogenesis and male infertility in testicular zinc finger protein Zfp318-knockout mice
Zfp318, a mouse gene with a Cys2/His2 zinc finger motif, is mainly expressed in germ cells in the testis. It encodes two alternative transcripts, which regulate androgen receptor-mediated transcriptional activation or repression by overexpression of them. However, the role of Zfp318 is still obscure in vivo, especially in spermatogenesis. To elucidate the role of Zfp318 during gamete production, we established a knockout mouse line. Zfp318-null male mice exhibited infertility, whereas Zfp318-null female mice displayed normal fertility. ZFP318 was expressed during multiple stages of spermatogenesis, from spermatocytes to round spermatids. The nuclei of secondary spermatocytes showed high levels of expression. Histological analysis and quantitative analysis of DNA content showed decreased numbers of both spermatids in the seminiferous tubules and mature spermatozoa in the epididymides of Zfp318-null mice. These results suggest that Zfp318 is expressed as a functional protein in testicular germ cells and plays an important role in meiosis during spermatogenesis
PROPOSAL OF SINGLE-FLUX-QUANTUM LOGIC DEVICE
A new type of logic gate that can be designed using a nonhysteretic Josephson weak link is proposed. The basic component of the proposed device is a one-junction interferometer, and a logic state is represented by either a zero or a single-flux-quantum. In contrast to the “Parametric Quantron,” this device is designed to operate without a three-phase clock and the dependence of the junction critical current on magnetic field is not used. The switching behavior of the device was simulated by computer and an analytical expression for the switching delay has been obtained
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