123 research outputs found
Ga-substitution effects in the weak ferromagnetic oxide LaCoRhO
Magnetization and x-ray diffraction have been measured on polycrystalline
samples of LaCoRhGaO for in
order to understand the spin state of Co through the Ga
substitution effect. The ferromagnetic order in LaCoRhO
below 15 K is dramatically suppressed by the Ga substitution, where the
ferromagnetic volume fraction is linearly decreased. The normal state
susceptibility also systematically decreases with the Ga content, from which we
find that one Ga ion reduces 4.6 per formula unit. We have
evaluated how the concentration of the high-spin state Co changes with
temperature by using an extended Curie-Weiss law, and have found that the
substituted Rh ion stabilizes the high-spin state Co ion down to
low temperatures. We find that Ga preferentially replaces the high-spin
state Co, which makes a remarkable contrast to our previous finding that
Rh preferentially replaces the low-spin state Co. These results
strongly suggest that the magnetically excited state of LaCoO at room
temperature is a mixed state of high-spin state Co and low-spin state
Co.Comment: 5 pages, 6 figure
Static magnetic moments revealed by muon spin relaxation and thermodynamic measurements in quantum spin ice YbTiO
We present muon spin relaxation (SR) and specific-heat versus
temperature measurements on polycrystalline and single-crystal samples
of the pyrochlore magnet YbTiO. exhibits a sharp peak at a
of 0.21 and 0.26~K for the single-crystal and polycrystalline
samples respectively. For both samples, the magnetic entropy released between
50~mK and 30~K amounts to per Yb. At temperatures below
we observe a steep drop in the asymmetry of the zero-field SR time spectra
at short time scales, as well as a decoupling of the muon spins from the
internal field in longitudinal magnetic fields of ~T for both the
polycrystalline and single-crystal samples. These muon data are indicative of
static magnetic moments. Our results are consistent with the onset of
long-range magnetic order in both forms of YbTiO.Comment: 6 pages, 4 figures, accepted to PR
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