Strong coupling among spontaneous structural symmetric breaking,magnetism,and metallicity in an intrinsic polar magnetic metal can give rise to novel physical phenomena and holds great promise for applications in spin...Strong coupling among spontaneous structural symmetric breaking,magnetism,and metallicity in an intrinsic polar magnetic metal can give rise to novel physical phenomena and holds great promise for applications in spintronics.Here,we elucidate the mechanism of magnetic polarity in the recently discovered polar metal Sr_(3)Co_(2)O_(7).Our first-principles calculations reveal that both the spontaneous polar displacements and the metallicity originate from charge disproportionation of Co ions.This is characterized by an inverted ligand-field splitting of the Co t_(2g) orbitals at one site,while the metallic behavior is preserved by the t_(2g) orbitals at both sites.Charge disproportionation,which originates from the on-site Hubbard U interaction,stabilizes the asymmetric phase.We thus propose that in related transition metal oxides,charge disproportionation within specific orbitals can concurrently drive metallicity and polarity,enabling strong coupling between these properties.More remarkably,this mechanism allows for the coexistence of magnetism,as evidenced in Sr_(3)Co_(2)O_(7).Our findings highlight a promising avenue for realizing polar magnetic metals and provide a new design principle for exploring multifunctional materials.展开更多
A new method of synthesizing single-component molecular conductor [Ni(dmit)2] by the reaction 2(Me4N)[Ni(dmit)2]2 [Ni(dmit)2] + (Me4N)[Ni(dmit)2] is reported. [Ni(dmit)2] exhibits a semiconductive behavior above 167...A new method of synthesizing single-component molecular conductor [Ni(dmit)2] by the reaction 2(Me4N)[Ni(dmit)2]2 [Ni(dmit)2] + (Me4N)[Ni(dmit)2] is reported. [Ni(dmit)2] exhibits a semiconductive behavior above 167 K, while from 167 K down to the measuring limit of 60 K, it exhibits metallic conductivity.展开更多
We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition bet...We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition between the ferromagnetic interaction of Fe3+and Fe5+ions and the antiferromagnetic one of Fe3+and Fe3+ions results in a unidirectional anisotropy in the cluster-glass system.An antiferromagnetically interfacial exchange coupling constant Ji1.95 meV at the cluster-glass region was yielded by fitting the cooling field-dependence of the exchange bias field.展开更多
Ni_(1-x)Co_(x)O nanoparticles were synthesized by a solution diffusion synergistic capture doping method and subsequent heat treatment.The charge disproportionation of the Ni ions promoted the REDOX reaction of Ni_(1-...Ni_(1-x)Co_(x)O nanoparticles were synthesized by a solution diffusion synergistic capture doping method and subsequent heat treatment.The charge disproportionation of the Ni ions promoted the REDOX reaction of Ni_(1-x)Co_(x)O electrode materials and improved their electrochemical performance.After incorporating Co atoms into the NiO structure.展开更多
Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semicond...Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.12274309 for H.-F.H.and J.-X.Y.)NERSC award (Grant No.BES-ERCAP0037158)。
文摘Strong coupling among spontaneous structural symmetric breaking,magnetism,and metallicity in an intrinsic polar magnetic metal can give rise to novel physical phenomena and holds great promise for applications in spintronics.Here,we elucidate the mechanism of magnetic polarity in the recently discovered polar metal Sr_(3)Co_(2)O_(7).Our first-principles calculations reveal that both the spontaneous polar displacements and the metallicity originate from charge disproportionation of Co ions.This is characterized by an inverted ligand-field splitting of the Co t_(2g) orbitals at one site,while the metallic behavior is preserved by the t_(2g) orbitals at both sites.Charge disproportionation,which originates from the on-site Hubbard U interaction,stabilizes the asymmetric phase.We thus propose that in related transition metal oxides,charge disproportionation within specific orbitals can concurrently drive metallicity and polarity,enabling strong coupling between these properties.More remarkably,this mechanism allows for the coexistence of magnetism,as evidenced in Sr_(3)Co_(2)O_(7).Our findings highlight a promising avenue for realizing polar magnetic metals and provide a new design principle for exploring multifunctional materials.
基金supported by the National Natural Science Foundation of China(No.20172034)Foundation for Univemity Key Teacher by Ministry of Educationthe grant for the State Key Program of China.
文摘A new method of synthesizing single-component molecular conductor [Ni(dmit)2] by the reaction 2(Me4N)[Ni(dmit)2]2 [Ni(dmit)2] + (Me4N)[Ni(dmit)2] is reported. [Ni(dmit)2] exhibits a semiconductive behavior above 167 K, while from 167 K down to the measuring limit of 60 K, it exhibits metallic conductivity.
基金supported by the National Basic Research Program of Chinathe National Natural Sciences Foundation of China(Grant No.11205015)+1 种基金the Natural Sciences Foundation of Beijing(Grant No.1113017)Beijing Area Logistics System&Technology Major Laboratory and the Logistics Management and Engineering Innovation Platform of Beijing Wuzi University
文摘We observed an exchange bias effect in La0.5Ca0.5FeO3 perovskite compound.The exchange bias is associated with the charge disproportionation transition from Fe4+ions to Fe3+and Fe5+ions below 175 K.The competition between the ferromagnetic interaction of Fe3+and Fe5+ions and the antiferromagnetic one of Fe3+and Fe3+ions results in a unidirectional anisotropy in the cluster-glass system.An antiferromagnetically interfacial exchange coupling constant Ji1.95 meV at the cluster-glass region was yielded by fitting the cooling field-dependence of the exchange bias field.
基金supported by the National Natural Science Foundation of China,no.11474124.
文摘Ni_(1-x)Co_(x)O nanoparticles were synthesized by a solution diffusion synergistic capture doping method and subsequent heat treatment.The charge disproportionation of the Ni ions promoted the REDOX reaction of Ni_(1-x)Co_(x)O electrode materials and improved their electrochemical performance.After incorporating Co atoms into the NiO structure.
基金financially supported by the National Key Research and Development Program of China (No.2021YFA0718900)the National Natural Science Foundation of China (No.62074014)the Xiaomi Scholar project。
文摘Metal-to-insulator transitions (MITs),which are achieved in 3d-band correlated transitional metal oxides,trigger abrupt variations in electrical,optical,and/or magnetic properties beyond those of conventional semiconductors.Among such material families,iron(Fe:3d^(6)4s^(2))-containing oxides pique interest owing to their widely tunable MIT properties,which are associated with the various valence states of Fe.Their potential electronic applications also show promise,given the large abundance of Fe on Earth.Representative MIT properties triggered by critical temperature (TMIT) were reported for ReFe_(2)O_(4)(Fe^(2.5+)),ReBaFe_(2)O_(5)(Fe^(2.5+)),Fe_(3)O_(4)(Fe^(2.67+)),Re_(1/3)Sr_(2/3)FeO_(3)(Fe^(3.67+)),Re Cu_(3)Fe_(4)O_(12)(Fe^(3.75+)),and Ca_(1-x)Sr_(x)FeO_(3)(Fe^(4+))(where Re represents rare-earth elements).The common feature of MITs of these Fe-containing oxides is that they are usually accompanied by charge ordering transitions or disproportionation associated with the valence states of Fe.Herein,we review the material family of Fe-containing MIT oxides,their MIT functionalities,and their respective mechanisms.From the perspective of potentially correlated electronic applications,the tunability of the TMITand its resultant resistive change in Fe-containing oxides are summarized and further compared with those of other materials exhibiting MIT functionality.In particular,we highlight the abrupt MIT and wide tunability of TMITof Fe-containing quadruple perovskites,such as Re Cu3Fe4O12.However,their effective material synthesis still needs to be further explored to cater to potential applications.
