arXiv subjects

N. Terada

Publications and source records attributed to N. Terada.

8 recordsLinked to original sources

arXiv2022

Unusually strong electronic correlation and field-induced ordered phase in YbCo$_2$

We report the first study of electrical resistivity, magnetization, and specific heat on YbCo$_2$. The measurements on a single-phased sample of YbCo$_2$ bring no evidence of magnetic ordering down to 0.3 K in a zero magnetic field. The manifestations of low Kondo temperature are observed. The specific heat value divided by temperature, C/T, keeps increasing logarithmically beyond 7 J/mol.K2 with decreasing temperature down to 0.3 K without no sign of magnetic ordering, suggesting a very large electronic specific heat. Analysis of the magnetic specific heat indicates that the large portion of the low-temperature specific heat is not explained simply by the low Kondo temperature but is due to the strong intersite magnetic correlation in both the 3d and 4f electrons. Temperature-dependent measurements under static magnetic fields up to 7 T are carried out, which show the evolution of field-induced transition above 2 T. The transition temperature increases with increasing field, pointing to a ferromagnetic character. The extrapolation of the transition temperature to zero field suggests that YbCo$_2$ is in the very proximity of the quantum critical point. These results indicate that in the unique case of YbCo$_2$, the itinerant electron magnetism of Co 3d-electrons and the Kondo effect within the vicinity of quantum criticality of Yb 4f-local moments can both play a role.

cond-mat.str-el↗

arXiv2021

Mars' atmospheric neon suggests volatile-rich primitive mantle

Martian atmospheric neon (Ne) has been detected by Viking and also found as trapped gas in Martian meteorites, though its abundance and isotopic composition have not been well determined. Because the timescale of Ne loss via atmospheric escape estimated from recent measurements with MAVEN is short (0.6--1 $\times$ 10$^8$ years), the abundance and isotope composition of Martian atmospheric Ne reflect recent atmospheric gas supply mostly from volcanic degassing. Thus, it can serve as a probe for the volatile content of the interior. Here we show that the tentatively-informed atmospheric Ne abundance suggests recent active volcanism and the mantle being richer in Ne than Earth's mantle today by more than a factor of 5--80. The estimated mantle Ne abundance requires efficient solar nebular gas capture or accretion of Ne-rich materials such as solar-wind-implanted dust in the planet formation stage, both of which provide important constraints on the abundance of other volatile elements in the interior and the accretion history of Mars. More precise determination of atmospheric Ne abundance and isotopic composition by in situ analysis or Mars sample return is crucial for distinguishing the possible origins of Ne.

astro-ph.EP↗

arXiv2017

Universal magneto-orbital ordering in the divalent $A$-site quadruple perovskite manganites $A$Mn$_7$O$_{12}$ ($A$ = Ca, Sr, Cd, and Pb)

Through analysis of variable temperature neutron powder diffraction data, we present solutions for the magnetic structures of SrMn$_7$O$_{12}$, CdMn$_7$O$_{12}$, and PbMn$_7$O$_{12}$ in all long-range ordered phases. The three compounds were found to have magnetic structures analogous to that reported for CaMn$_7$O$_{12}$. They all feature a higher temperature lock-in phase with \emph{commensurate} magneto-orbital coupling, and a delocked, multi-\textbf{k} magnetic ground state where \emph{incommensurate} magneto-orbital coupling gives rise to a constant-moment magnetic helix with modulated spin helicity. CdMn$_7$O$_{12}$ represents a special case in which the orbital modulation is commensurate with the crystal lattice and involves stacking of fully and partially polarized orbital states. Our results provide a robust confirmation of the phenomenological model for magneto-orbital coupling previously presented for CaMn$_7$O$_{12}$. Furthermore, we show that the model is universal to the $A^{2+}$ quadruple perovskite manganites synthesised to date, and that it is tunable by selection of the $A$-site ionic radius.

cond-mat.str-el↗

arXiv2015

Precise determination of $^{12}_Λ$C level structure by $γ$-ray spectroscopy

Level structure of the $^{12}_Λ$C hypernucleus was precisely determined by means of $γ$-ray spectroscopy. We identified four $γ$-ray transitions via the $^{12}$C$(π^{+},K^{+}γ)$ reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet $(2^{-}_{1},1^{-}_{1})$ was measured to be $161.5\pm0.3\text{(stat)}\pm0.3\text{(syst)}$\,keV from the direct $M1$ transition. Excitation energies of the $1^{-}_{2}$ and $1^{-}_{3}$ states were measured to be $2832\pm3\pm4$\,keV and $6050\pm8\pm7$\,keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of $Λ$ hypernuclei.

nucl-ex↗

arXiv2012

Report on strangeness photoproduction experiments performed with the Neutral Kaon Spectrometer 2

An experiment designed to investigate the strangeness photoproduction process using a tagged photon beam in the energy range of 0.90 -1.08 GeV incident on a liquid deuterium target was successfully performed. The purpose of the experiment was to measure the production of neutral kaons and the lambda particles on a deuteron. The generation of photo produced particles was verified by the measurement of their decayed charged particles in the Neutral Kaon Spectrometer 2. The reconstructed invariant mass distributions were achieved by selecting events where two or more particles tracks were identified. Preliminary results are presented here.

nucl-ex↗

arXiv2011

High-order Ho multipoles in HoB2C2 observed with soft resonant x-ray diffraction

Soft resonant x-ray Bragg diffraction (SRXD) at the Ho M$_{4,5}$ edges has been used to study Ho $4f$ multipoles in the combined magnetic and orbitally ordered phase of HoB$_2$C$_2$. A full description of the energy dependence for both $σ$ and $π$ incident x-rays at two different azimuthal angles, as well as the ratio $I_σ/I_π$ as a function of azimuthal angle for a selection of energies, allows a determination of the higher order multipole moments of rank 1 (dipole) to 6 (hexacontatetrapole). The Ho 4f multipole moments have been estimated, indicating a dominant hexadecapole (rank 4) order with an almost negligible influence from either the dipole or the octupole magnetic terms. The analysis incorporates both the intra-atomic magnetic and quadrupolar interactions between the 3d core and 4f valence shells as well as the interference of contributions to the scattering that behave differently under time reversal. Comparison of SRXD, neutron diffraction and non resonant x-ray diffraction shows that the magnetic and quadrupolar order parameter are distinct. The $(0 0 1/2)$ component of the magnetic order exhibits a Brillouin type increase below the orbital ordering temperature T$_Q$, while the quadrupolar order increases more sharply. We conclude the quadrupolar interaction is strong, but quadrupolar order only occurs when the magnetic order gives rise to a quasi doublet ground state, which results in a lock-in of the orbitals at T$_Q$.

cond-mat.str-el↗

arXiv2007

Optimised Curing of Silver Ink Jet Based Printed Traces

Manufacturing electronic devices by printing techniques with low temperature sintering of nano-size material particles can revolutionize the electronics industry in coming years. The impact of this change to the industry can be significant enabling low-cost products and flexibility in manufacturing. implementation of a new production technology with new materials requires thorough elementary knowledge creation. It should be noticed that although some of first electronic devices ideally can be manufactured by printing, at the present several modules are in fact manufactured by using hybrid techniques (for instance photolithography, vapor depositions, spraying, etc...).

cond-mat.mtrl-sci↗

arXiv2007

Electric Polarization Induced by a Proper Helical Magnetic Ordering in a Delafossite Multiferroic CuFe1-xAlxO2

Multiferroic CuFe1-xAlxO2 (x=0.02) exhibits a ferroelectric ordering accompanied by a proper helical magnetic ordering below T=7K under zero magnetic field. By polarized neutron diffraction and pyroelectric measurements, we have revealed a one-to-one correspondence between the spin helicity and the direction of the spontaneous electric polarization. This result indicates that the spin helicity of the proper helical magnetic ordering is essential for the ferroelectricity in CuFe1-xAlxO2. The induction of the electric polarization by the proper helical magnetic ordering is, however, cannot be explained by the Katsura-Nagaosa-Balatsky model, which successfully explains the ferroelectricity in the recently explored ferroelectric helimagnets, such as TbMnO3. We thus conclude that CuFe1-xAlxO2 is a new class of magnetic ferroelectrics.

cond-mat.str-el↗