Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimen...Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimensional(2D)rhombic lattice Fe-metal-organic framework(Fe-MOF)with frustrated antiferromagnetism.This Fe-MOF exhibits a high frustration factor f=|θCW|/TN≥315,and its long-range magnetic order is suppressed down to 180 mK.Detailed theoretical calculations demonstrate strong antiferromagnetic coupling between adjacent Fe3+ions,indicating the potential of a classical spin-liquid-like behavior.Notably,a T-linear heat capacity parameter,γ,originating from electronic contributions and with magnetic field independence up to 8 T,can be observed in the specific heat capacity measurements at low-temperature,providing further proof for the spin-liquid-like behavior.This work highlights the potential of MOF materials in geometrically frustrated systems,and will promote the research of exotic quantum physics phenomena.展开更多
Perovskite oxides are significant candidates to develop electrochemical catalysts for water oxidation in consideration of their high catalysis capacity,low costing and excellent stability.Rational design of coordinati...Perovskite oxides are significant candidates to develop electrochemical catalysts for water oxidation in consideration of their high catalysis capacity,low costing and excellent stability.Rational design of coordination structure and overcoming poor electronic transport are regarded as critical factors for outstanding perovskite-based oxygen evolution reaction (OER) catalysts.Herein,we report a mild chemical oxidation method to realize ligancy engineering from strongly-correlated brownmillerite Sr2Co2O5 to perovskite phase Sr2Co2O5.5,along with abundant oxygen vacancies formation and greatly boosted electric conductivity,which helps to form the active species of Co hydroxide/oxide on the surface of catalysts.The coupling effect of catalytic kinetics and unimpeded electronic movement brings high OER activities in Sr2Co2O5.5 with a low onset potential and a small Tafel slope.Our work not only displays in-depth understanding into the relationship among catalysis performance and multiple physical degrees of freedom,but also paves a new path to develop high-efficient electrochemical catalysts.展开更多
In recent years,few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional(2D)magnets into next-generation spintronic devices.The SrRuO...In recent years,few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional(2D)magnets into next-generation spintronic devices.The SrRuO_(3)monolayer is a rare example of stable 2D magnetism under ambient conditions,but only weak ferromagnetism or antiferromagnetism has been found.The biatomic layer SrRuO_(3)as another environmentally inert 2D magnetic system has been paid less attention heretofore.Here we study both the bi-atomic layer and monolayer SrRuO_(3)in(SrRuO_(3))n/(SrTiO_(3))m(n=1,2)superlattices in which the SrTiO3 serves as a non-magnetic and insulating space layer.Although the monolayer exhibits arguably weak ferromagnetism,we find that the bi-atomic layer exhibits exceedingly strong ferromagnetism with a Tc of 125 K and a saturation magnetization of 1.2μB/Ru,demonstrated by both superconducting quantum interference device(SQUID)magnetometry and element-specific X-ray circular dichroism.Moreover,in the bi-atomic layer SrRuO_(3),we demonstrate that random fluctuations and orbital reconstructions inevitably occurring in the 2D limit are critical to the electrical transport,but are much less critical to the ferromagnetism.Our study demonstrates that the bi-atomic layer SrRuO_(3)is an exceedingly strong 2D ferromagnetic oxide which has great potentials for applications of ultracompact spintronic devices.展开更多
基金supported by the National Key Research and Development Program of China(No.2021YFA1600800)the National Natural Science Foundation of China(Nos.11975234,12075243,12005227,12105286,121350122,U2032150,12275271,12205305,and U1932211)+5 种基金the Natural Science Foundation of Anhui Province(Nos.2208085QA14 and 2208085J13)the Users with Excellence Program of Hefei Science Center CAS(Nos.2020HSC-UE002,2020HSC-CIP013,2021HSC-UE002,and 2021HSC-UE003)the Major science and technology project of Anhui Province(No.202103a05020025)the Key Program of Research and Development of Hefei Science Center,CAS(Nos.2021HSC-KPRD002 and 2021HSC-KPRD003)the Fundamental Research Funds for the Central Universities(No.WK 2310000103)partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘Discovering more and new geometrically frustrated systems remains an active point of inquiry in fundamental physics for the existence of unusual states of matter.Here,we report spin-liquid-like behavior in a two-dimensional(2D)rhombic lattice Fe-metal-organic framework(Fe-MOF)with frustrated antiferromagnetism.This Fe-MOF exhibits a high frustration factor f=|θCW|/TN≥315,and its long-range magnetic order is suppressed down to 180 mK.Detailed theoretical calculations demonstrate strong antiferromagnetic coupling between adjacent Fe3+ions,indicating the potential of a classical spin-liquid-like behavior.Notably,a T-linear heat capacity parameter,γ,originating from electronic contributions and with magnetic field independence up to 8 T,can be observed in the specific heat capacity measurements at low-temperature,providing further proof for the spin-liquid-like behavior.This work highlights the potential of MOF materials in geometrically frustrated systems,and will promote the research of exotic quantum physics phenomena.
基金This work was financially supported by the National Key R&D Program of Chnia(No.2017YFA0207301)the National Natural Science Foundation of China(Nos.U1632154,21890751,91745113,11621063,21601172,and J1030412)+2 种基金National Program for Support of Top-notch Young Professionals,the Fundamental Research Funds for the Central Universities(No.WK2090050043)Youth Innovation Promotion Association of CAS(No.2018500)Users with Excellence Project of Hefei Science Center(No.CAS2018HSCUE002).
文摘Perovskite oxides are significant candidates to develop electrochemical catalysts for water oxidation in consideration of their high catalysis capacity,low costing and excellent stability.Rational design of coordination structure and overcoming poor electronic transport are regarded as critical factors for outstanding perovskite-based oxygen evolution reaction (OER) catalysts.Herein,we report a mild chemical oxidation method to realize ligancy engineering from strongly-correlated brownmillerite Sr2Co2O5 to perovskite phase Sr2Co2O5.5,along with abundant oxygen vacancies formation and greatly boosted electric conductivity,which helps to form the active species of Co hydroxide/oxide on the surface of catalysts.The coupling effect of catalytic kinetics and unimpeded electronic movement brings high OER activities in Sr2Co2O5.5 with a low onset potential and a small Tafel slope.Our work not only displays in-depth understanding into the relationship among catalysis performance and multiple physical degrees of freedom,but also paves a new path to develop high-efficient electrochemical catalysts.
基金financially supported by the National Natural Science Foundation of China(U1832142 and 21805269)the National Key R&D Program of China(2018YFB0703602 and 2017YFA0303500)+6 种基金the Youth Innovation Promotion Association,CAS(Y202092)the Fundamental Research Funds for the Central Universities(WK2340000094)The University Synergy Innovation Program of Anhui Province(GXXT-2020-003)Anhui Provincial Natural Science Foundation(1808085QA08)the Key Research Program of Frontier Sciences(QYZDYSSW-SLH011)China Postdoctoral Science Foundation(2017M620261,2019TQ0293 and 2020M671868)the National Synchrotron Radiation Laboratory Joint funds of University of Science and Technology of China(KY2060000156 and KY2340000114)。
基金the National Natural Science Foundation of China(Nos.52072244 and 12104305)the Science and Technology Commission of Shanghai Municipality(No.21JC1405000)+1 种基金the ShanghaiTech Startup Fund.This research used resources of the Advanced Photon Source,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract(No.DE-AC02-06CH11357)the Advanced Light Source,a U.S.DOE Office of Science User Facility under Contract(No.DE-AC02-05CH11231).
文摘In recent years,few-layer or even monolayer ferromagnetic materials have drawn a great deal of attention due to the promising integration of two-dimensional(2D)magnets into next-generation spintronic devices.The SrRuO_(3)monolayer is a rare example of stable 2D magnetism under ambient conditions,but only weak ferromagnetism or antiferromagnetism has been found.The biatomic layer SrRuO_(3)as another environmentally inert 2D magnetic system has been paid less attention heretofore.Here we study both the bi-atomic layer and monolayer SrRuO_(3)in(SrRuO_(3))n/(SrTiO_(3))m(n=1,2)superlattices in which the SrTiO3 serves as a non-magnetic and insulating space layer.Although the monolayer exhibits arguably weak ferromagnetism,we find that the bi-atomic layer exhibits exceedingly strong ferromagnetism with a Tc of 125 K and a saturation magnetization of 1.2μB/Ru,demonstrated by both superconducting quantum interference device(SQUID)magnetometry and element-specific X-ray circular dichroism.Moreover,in the bi-atomic layer SrRuO_(3),we demonstrate that random fluctuations and orbital reconstructions inevitably occurring in the 2D limit are critical to the electrical transport,but are much less critical to the ferromagnetism.Our study demonstrates that the bi-atomic layer SrRuO_(3)is an exceedingly strong 2D ferromagnetic oxide which has great potentials for applications of ultracompact spintronic devices.
