超高圧下における遷移金属酸化物の金属化と磁気モーメント消失

概要

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Shock and static compression studies of the transition metal monoxides MnO, CoO, and NiO were carried out in the pressure range of 100 GPa. Shock-induced phase transitions of MnO and CoO were first observed at 90 and 81 GPa, respectively, but not in NiO up to 147 GPa. High-pressure X-ray diffraction study using a diamond anvil cell confirmed these transitions at corresponding pressures, and showed that the highest-pressure phases of MnO and CoO are metallic with NiAs-type and magnetically collapsed rocksalt structures, respectively. First-principles calculation based on the density functional formalism successfully explained these experimental results, indicating that both MnO and CoO undergo insulator-metal transition accompanied by spin-pairing due to the breakdown of electron correlation at high pressure. The present results are compared with phase transitions previously observed in FeO and Fe_2O_3.
社団法人日本磁気学会の論文
2000-02-01