Bulletin of the Graduate School of Integrated Arts and Sciences, Hiroshima University. II, Studies in environmental sciences Volume 5
2010-12-31 発行

The research of sample preparation and measurement of physical properties of rare-earth compounds : As examples on the low carrier rare-earth pnictide Yb4As3, and the rare-earth hydride SmH2+δ <Summaries of the Doctoral Theses>

試料作製・評価による希土類化合物の研究 : 少数キャリヤー系希土類プニクタイドYB4AS3及び希土類水素化物SmH2+δを例として <学位論文要旨>
Nakamura, Osamu
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abstract
Physical properties were investigated for Yb4As3 and SmH2+δ. In the case of Yb4As3, the Sommerfeld coefficient γ = 200 mJ/(K2 mole) of Yb4As3 does not originate from impurities. The change of γ is observed when the specific heat is measured in a magnetic field of 1 T. The Korringa law (T1T=constant) holds only in the narrow temperature range between 20 K and 10 K. Their physical properties of Yb4As3 cannot be described by a simple Fermi liquid picture. In the case of bulk SmH2.16, the temperature dependence of the magnetic susceptibility and of the specific heat in the paramagnetic region can be described by assuming all Sm ions are Sm3+; ground state Γ8. The Cp/T exhibits an antiferromagnetic spin wave and that the Sommerfeld coefficient γ is 150 mJ/(K2 mole). In the case of SmH2+δ films, the reflectivity shows a minimum at 1–2 eV, which is possibly due to a plasma edge. The minimum show a red shift as the H/Sm ratio increases. The transmittance has a maximum at about 1 eV. The line shape of the optical conductivity cannot be explained in terms of a simple single carrier model. In the range 0.25-0.6 eV, the relaxation time increases as δ increases.
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