83 research outputs found
Absence of Edge Localized Moments in the Doped Spin-Peierls System CuGeSiO
We report the observation of nuclear quadrupole resonance (NQR) of Cu from
the sites near the doping center in the spin-Peierls system
CuGeSiO. The signal appears as the satellites in the Cu NQR
spectrum, and has a suppressed nuclear spin-lattice relaxation rate indicative
of a singlet correlation rather than an enhanced magnetic correlation near the
doping center. Signal loss of Cu nuclei with no neighboring Si is also
observed. We conclude from these observations that the doping-induced moments
are not in the vicinity of the doping center but rather away from it.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev. Let
Phase Inhomogeneity of the Itinerant Ferromagnet MnSi at High Pressures
The pressure induced quantum phase transition of the weakly itinerant
ferromagnet MnSi is studied using zero-field NMR spectroscopy and
relaxation. Below , the intensity of the signal and the
nuclear spin-lattice relaxation is independent of pressure, even though the
amplitude of the magnetization drops by 20% from the ambient pressure
amplitude. For , the decreasing intensity within the experimentally
detectable bandwidth signals the onset of an inhomogeneous phase that persists
to the highest pressure measured, , which is well beyond the
known critical pressure . Implications for the non-Fermi Liquid
behavior observed for are discussed.Comment: 4 pages, 4 figure
Unconventional ferromagnetic and spin-glass states of the reentrant spin glass Fe0.7Al0.3
Spin excitations of single crystal Fe0.7Al0.3 were investigated over a wide
range in energy and reciprocal space with inelastic neutron scattering. In the
ferromagnetic phase, propagating spin wave modes become paramagnon-like
diffusive modes beyond a critical wave vector q0, indicating substantial
disorder in the long-range ordered state. In the spin glass phase, spin
dynamics is strongly q-dependent, suggesting remnant short-range spin
correlations. Quantitative model for S(energy,q) in the ``ferromagnetic'' phase
is determined.Comment: 4 pages, 5 figure
Itinerant-Electron Magnet of the Pyrochlore Lattice: Indium-Doped YMn2Zn20
We report on a ternary intermetallic compound, "YMn2Zn20", comprising a
pyrochlore lattice made of Mn atoms. A series of In-doped single crystals
undergo no magnetic long-range order down to 0.4 K, in spite of the fact that
the Mn atom carries a local magnetic moment at high temperatures, showing
Curie-Weiss magnetism. However, In-rich crystals exhibit spin-glass transitions
at approximately 10 K due to a disorder arising from the substitution, while,
with decreasing In content, the spin-glass transition temperature is reduced to
1 K. Then, heat capacity divided by temperature approaches a large value of 280
mJ K-2 mol-1, suggesting a significantly large mass enhancement for conduction
electrons. This heavy-fermion-like behavior is not induced by the Kondo effect
as in ordinary f-electron compounds, but by an alternative mechanism related to
the geometrical frustration on the pyrochlore lattice, as in (Y,Sc)Mn2 and
LiV2O4, which may allow spin entropy to survive down to low temperatures and to
couple with conduction electrons.Comment: 5 pages, 4 figures, J. Phys. Soc. Jpn., in pres
Bulk screening in core level photoemission from Mott-Hubbard and Charge-Transfer systems
We report bulk-sensitive hard X-ray ( = 5.95 KeV) core level
photoemission spectroscopy (PES) of single crystal VCrO
and the high- cuprate BiSrCaCuO (Bi2212).
VCrO exhibits low binding energy "satellites" to the V
"main lines" in the metallic phase, which are suppressed in the
antiferromagnetic insulator phase. In contrast, the Cu spectra of Bi2212
do not show temperature dependent features, but a comparison with soft X-ray
PES indicates a large increase in the "satellites" or weight
in the bulk. Cluster model calculations, including full multiplet structure and
a screening channel derived from the coherent band at the Fermi energy, give
very satisfactory agreement with experiments
Coexistence of double alternating antiferromagnetic chains in (VO)_2P_2O_7 : NMR study
Nuclear magnetic resonance (NMR) of 31P and 51V nuclei has been measured in a
spin-1/2 alternating-chain compound (VO)_2P_2O_7. By analyzing the temperature
variation of the 31P NMR spectra, we have found that (VO)_2P_2O_7 has two
independent spin components with different spin-gap energies. The spin gaps are
determined from the temperature dependence of the shifts at 31P and 51V sites
to be 35 K and 68 K, which are in excellent agreement with those observed in
the recent inelastic neutron scattering experiments [A.W. Garrett et al., Phys.
Rev. Lett. 79, 745 (1997)]. This suggests that (VO)_2P_2O_7 is composed of two
magnetic subsystems showing distinct magnetic excitations, which are associated
with the two crystallographically-inequivalent V chains running along the b
axis. The difference of the spin-gap energies between the chains is attributed
to the small differences in the V-V distances, which may result in the
different exchange alternation in each magnetic chain. The exchange
interactions in each alternating chain are estimated and are discussed based on
the empirical relation between the exchange interaction and the interatomic
distance.Comment: 10 pages, 11 embedded eps figures, REVTeX, Submitted to Phys. Rev.
Magnetic fluctuations in frustrated Laves hydrides R(Mn_{1-x}Al_{x})_{2}H_{y}
By neutron scattering, we have studied the spin correlations and spin
fluctuations in frustrated Laves hydrides, where magnetic disorder sets in the
topologically frustrated Mn lattice. Below the transition towards short range
magnetic order, static spin clusters coexist with fluctuating and alsmost
uncorrelated spins. The magnetic response shows a complexe lineshape, connected
with the presence of the magnetic inhomogeneities. Its analysis shows the
existence of two different processes, relaxation and local excitations, for the
spin fluctuations below the transition. The paramagnetic fluctuations are
discussed in comparison with classical spin glasses, cluster glasses, and non
Fermi liquid itinerant magnets
Nonlinear magnetic susceptibility and aging phenomena in reentrant ferromagnet: CuCoCl-FeCl graphite bi-intercalation compound
Linear and nonlinear dynamic properties of a reentrant ferromagnet
CuCoCl-FeCl graphite bi-intercalation compound are
studied using AC and DC magnetic susceptibility. This compound undergoes
successive phase transitions at the transition temperatures (= 16 K),
(= 9.7 K), and (= 3.5 K). The static and dynamic behaviors of
the reentrant spin glass phase below are characterized by those of
normal spin glass phase with critical exponent = 0.57 0.10, a
dynamic critical exponent = 8.5 1.8, and an exponent (= 1.55
0.13) for the de Almeida -Thouless line. A prominent nonlinear
susceptibility is observed between and and around ,
suggesting a chaotic nature of the ferromagnetic phase () and the helical spin ordered phase (). The
aging phenomena are observed both in the RSG and FM phases, with the same
qualitative features as in normal spin glasses. The aging of zero-field cooled
magnetization indicates a drastic change of relaxation mechanism below and
above . The time dependence of the absorption
is described by a power law form () in the
ferromagnetic phase, where at =
0.05 Hz and = 7 K. No -scaling law for
[] is observed.Comment: 14 pages, 16 figures, and 2 table
MicroRNA-196b is an independent prognostic biomarker in patients with pancreatic cancer
microRNA-196bは膵癌において異常高発現しており,多変量解析で不良な予後に相関した.その阻害剤は膵癌細胞株において抗腫瘍効果を示すことから,microRNA-196bは診断バイオマーカーおよび治療標的となることが示唆された
Support for UNRWA's survival
The United Nations Relief and Works Agency for Palestine Refugees in the Near East (UNRWA) provides life-saving humanitarian aid for 5·4 million Palestine refugees now entering their eighth decade of statelessness and conflict. About a third of Palestine refugees still live in 58 recognised camps. UNRWA operates 702 schools and 144 health centres, some of which are affected by the ongoing humanitarian disasters in Syria and the Gaza Strip. It has dramatically reduced the prevalence of infectious diseases, mortality, and illiteracy. Its social services include rebuilding infrastructure and homes that have been destroyed by conflict and providing cash assistance and micro-finance loans for Palestinians whose rights are curtailed and who are denied the right of return to their homeland
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