Recently,a series of novel compounds Ba3MX5(M=Fe,Ti,V;X=Se,Te)with hexagonal crystal structures composed of quasi-1-dimensional(1D)magnetic chains has been synthesized by our research team using high-pressure and high...Recently,a series of novel compounds Ba3MX5(M=Fe,Ti,V;X=Se,Te)with hexagonal crystal structures composed of quasi-1-dimensional(1D)magnetic chains has been synthesized by our research team using high-pressure and high-temperature methods.The initial hexagonal phases persist to the maximum achievable pressure,while spin configurations and magnetic interactions may change dramatically as a result of considerable reductions in interchain separations upon pressurization.These compounds therefore offer unique possibilities for studying the evolution of intrinsic electronic structures in quasi-1D magnetic systems.Here we present a systematic investigation of Ba9Fe3Te15,in which the interchain separations between trimerized 1D chains(~10.2Å)can be effectively modulated by external high pressure.The crystal structure especially along the 1D chains exhibits an abnormal expansion at^GPa,which accompanies trimerization entangled anomalous mixed-high-low spin transition.An insulator-metal transition has been observed under high pressure as a result of charge-transfer gap closing.Pressure-induced superconductivity emerges at 26 GPa,where the charge-transfer gap fully closes,3D electronic configuration forms and local spin fully collapses.展开更多
Iron oxide is one of the most important components in the Earth’s mantle.The recent discovery of the stable presence of Fe_(5)O_(6) in the Earth’s mantle environment has stimulated significant interests in understan...Iron oxide is one of the most important components in the Earth’s mantle.The recent discovery of the stable presence of Fe_(5)O_(6) in the Earth’s mantle environment has stimulated significant interests in understanding of this new category of iron oxides.We report the electronic structure and magnetic properties of Fe_(5)O_(6) calculated by the density functional theory plus dynamic mean field theory(DFT+DMFT)approach.Our calculations indicate that Fe_(5)O_(6) is a conductor at ambient pressure with dominant Fe-3 d density of states at the Fermi level.The magnetic moments of iron atoms at three non-equivalent crystallographic sites in Fe_(5)O_(6) collapse at significantly different rates under pressure.This site-selective collapse of magnetic moments originates from the shifting of energy levels and the consequent charge transfer among the Fe-3 d orbis when Fe_(5)O_(6) is being compressed.Our simulations suggest that there could be high conductivity and volume contraction in Fe_(5)O_(6) at high pressure,which may induce anomalous features in seismic velocity,energy exchange,and mass distribution in the deep interior of the Earth.展开更多
基金Supported by the National Natural Science Foundation of China(Grant Nos.U1930401,11974410,11820101003,11921004 and 11534016)the National Key R&D Program of China(Grant Nos.2018YFA0305703,2018YFA0305700 and 2017YFA0302900).
文摘Recently,a series of novel compounds Ba3MX5(M=Fe,Ti,V;X=Se,Te)with hexagonal crystal structures composed of quasi-1-dimensional(1D)magnetic chains has been synthesized by our research team using high-pressure and high-temperature methods.The initial hexagonal phases persist to the maximum achievable pressure,while spin configurations and magnetic interactions may change dramatically as a result of considerable reductions in interchain separations upon pressurization.These compounds therefore offer unique possibilities for studying the evolution of intrinsic electronic structures in quasi-1D magnetic systems.Here we present a systematic investigation of Ba9Fe3Te15,in which the interchain separations between trimerized 1D chains(~10.2Å)can be effectively modulated by external high pressure.The crystal structure especially along the 1D chains exhibits an abnormal expansion at^GPa,which accompanies trimerization entangled anomalous mixed-high-low spin transition.An insulator-metal transition has been observed under high pressure as a result of charge-transfer gap closing.Pressure-induced superconductivity emerges at 26 GPa,where the charge-transfer gap fully closes,3D electronic configuration forms and local spin fully collapses.
基金the National Natural Science Foundation of China(Grant Nos.11604255 and U1930401)the Natural Science Basic Research Program of Shaanxi(Grant No.2021JM-001)。
文摘Iron oxide is one of the most important components in the Earth’s mantle.The recent discovery of the stable presence of Fe_(5)O_(6) in the Earth’s mantle environment has stimulated significant interests in understanding of this new category of iron oxides.We report the electronic structure and magnetic properties of Fe_(5)O_(6) calculated by the density functional theory plus dynamic mean field theory(DFT+DMFT)approach.Our calculations indicate that Fe_(5)O_(6) is a conductor at ambient pressure with dominant Fe-3 d density of states at the Fermi level.The magnetic moments of iron atoms at three non-equivalent crystallographic sites in Fe_(5)O_(6) collapse at significantly different rates under pressure.This site-selective collapse of magnetic moments originates from the shifting of energy levels and the consequent charge transfer among the Fe-3 d orbis when Fe_(5)O_(6) is being compressed.Our simulations suggest that there could be high conductivity and volume contraction in Fe_(5)O_(6) at high pressure,which may induce anomalous features in seismic velocity,energy exchange,and mass distribution in the deep interior of the Earth.
