32 research outputs found
Field-Induced Transition on Triangular Plane in the Spin Ice Compound Dy2Ti2O7
The origin of the lowest-temperature anomaly reported several years ago using
a polycrystalline sample of the spin ice compound Dy2Ti2O7 had remained
unresolved. Here we finally clarify its origin by susceptibility measurements
down to 65 mK using single crystals under accurate control of the magnetic
fields in two independent directions. We demonstrate that the transition is
induced under a subtle field combination that precisely cancel the
nearest-neighbor spin interactions acting on the spins on the triangular
lattice within the pyrochlore structure. Contrary to the other two fieldinduced
transitions, this transition is driven only by the interactions beyond the
nearest neighbors. Our observation thus provides the first qualitative evidence
for the essential importance of the dipolar interaction beyond the nearest
neighbors in the spin ice.Comment: submitted to PR
Magnetodielectric Response of the Spin-Ice Dy2Ti2O7
We report the magneto-dielectric response of single crystals of the spin-ice
compound Dy2Ti2O7 down to 0.26 K. The dielectric constant under zero magnetic
field exhibits a clear decrease reflecting the development of the local
two-spins-in, two-spins-out structure below about 1.2 K. Both the real and
imaginary parts of the dielectric constant under magnetic fields sensitively
respond to various changes in the spin structures. We found that the real part
can be described in terms of local spin correlations among the moments of
tetrahedra, rather than among individual Dy3+ moments. Using the peaks in the
imaginary part, we have constructed a precise field-temperature phase diagram
in the [111] field direction. We thus demonstrate that the magneto-dielectric
response can be a high-sensitivity local probe of the spin state of
geometrically frustrated systems.Comment: 6 pages, 6 figure
Superconductivity in In-doped AgPbBiTe3 compounds synthesized by high-pressure synthesis
NaCl-type metal tellurides (MTe) have been widely studied due to unique
physical properties. We investigated the In-doping effects on structural and
physical properties of Na-Cl type (AgPbBi)(1-x)/3InxTe and the superconducting
properties of the In-doped samples. Polycrystalline samples with x = 0-0.5 were
synthesized by utilizing high-pressure synthesis. For x = 0.2-0.5,
superconductivity was observed in magnetization measurements, where the highest
transition temperature (Tc) was 2.8 K for x = 0.4. We measured specific heat
for x = 0.4 and confirmed the bulk nature of the superconductivity. The
evolution of the Seebeck coefficient and lattice constant by In doping suggests
that In valence state is In+3, and the In doping generates electron carriers in
the (AgPbBi)(1-x)/3InxTe system.Comment: 12 pages, 5 figure
93Nb- and 27Al-NMR/NQR studies of the praseodymium based PrNb2Al20
International Conference on Strongly Correlated Electron Systems 2014 (SCES2014