Evolution from a ferromagnetic to a spin-glass regime in the spinel-type Cu(Cr1-xTix)2S4

Successive changes from ferromagnetic, re-entrant mixed, to spin-glass regime have been manifestly found with increasing Ti-composition x in the quaternary spinel-type Cu(Cr1-xTix)2S4 system. The Curie temperature Tc　decreases steeply with increasing x and this transition becomes ill-defined around x = 0.47. Two distinct transitions appear below Tc over the range x = 0.40 - 0.47. Coexistence of the ferromagnetism and spin-glass order would be observed below the Gabay and Toulouse transition TGT, owing to freezing of the transverse-spin components without changing of the ferromagnetic order parameter. Finally, at a yet lower temperature de Almeida-Thouless transition TAT, the longitudinal-spin component freezes randomly at which an irreversibility arises between zero-field-cooled (ZFC) and field-cooled (FC) magnetizations. Over the range of 0.47 ≤ x ≤ 0.85, a cusp of the ZFC magnetization is seen at Tg like conventional spin-glass. Specimens with x ≥ 0.90 remain paramagnetic down to 2.0 K. A magnetic phase diagram between T versus x has been obtained experimentally. The values of the multi critical point in 100 Oe is detected to be x = 0.47 and T = 7.40 K. The low field magnetization and the phase diagram are satisfactorily explained by the theory of Gabay and Toulouse on the basis of Heisenberg isotropic vector spin model rather than the Ising spin model

ショクヒン ノ サンカカンゲンデンイ ニ カンスル ケンキュウ

野菜・果実類の酸化還元電位を測定し,加熱したほうが食品の酸化還元電位が低下することが判った。これは(1)食品中のポリフェノラーゼなどが加熱により失活するため,抗酸化成分の酸化・分解が抑制されること,(2)加熱より細胞組織が柔軟化し,細胞内容物が細胞外に浸出しやすくなることなどが主な理由であると考えられた。また酸化還元電位の異なる食品の摂取試験から,人体の酸化還元電位よりも相対的に低い酸化還元電位を有する食品の摂取が人体(尿)の酸化還元電位を低くすることが示唆された。特に野菜・果実類を加熱して摂取することが,生で摂取するよりも,人体の酸化還元電位という指標から体内の酸化還元電位の改善に有効であることが示唆された

Evolution from a ferromagnetic to a spin-glass regime in the spinel-type Cu(Cr1-xTix)2S4

application/pdfSuccessive changes from ferromagnetic, re-entrant mixed, to spin-glass regime have been manifestly found with increasing Ti-composition x in the quaternary spinel-type Cu(Cr1-xTix)2S4 system. The Curie temperature Tc　decreases steeply with increasing x and this transition becomes ill-defined around x = 0.47. Two distinct transitions appear below Tc over the range x = 0.40 - 0.47. Coexistence of the ferromagnetism and spin-glass order would be observed below the Gabay and Toulouse transition TGT, owing to freezing of the transverse-spin components without changing of the ferromagnetic order parameter. Finally, at a yet lower temperature de Almeida-Thouless transition TAT, the longitudinal-spin component freezes randomly at which an irreversibility arises between zero-field-cooled (ZFC) and field-cooled (FC) magnetizations. Over the range of 0.47 ≤ x ≤ 0.85, a cusp of the ZFC magnetization is seen at Tg like conventional spin-glass. Specimens with x ≥ 0.90 remain paramagnetic down to 2.0 K. A magnetic phase diagram between T versus x has been obtained experimentally. The values of the multi critical point in 100 Oe is detected to be x = 0.47 and T = 7.40 K. The low field magnetization and the phase diagram are satisfactorily explained by the theory of Gabay and Toulouse on the basis of Heisenberg isotropic vector spin model rather than the Ising spin model