Physical properties,such as electrochemical and electromagnetic properties,of two-dimensional MXenes can be improved by enhancing their stability.However,MXenes fabricated via acid etching contain defects,which affect...Physical properties,such as electrochemical and electromagnetic properties,of two-dimensional MXenes can be improved by enhancing their stability.However,MXenes fabricated via acid etching contain defects,which affect their physical properties.In this study,a method to effectively remove Al residues using only water during MXene fabrication while maintaining structural stability is proposed.The fabrication and intercalation of MXenes are controlled via epitaxial self-intercalation of H_(2)O-etched Cr_(2)(AlLi)C.On the basis of this mechanism,the room-temperature ferromagnetism of two-dimensional few-layered Cr_(2)CT_(x)MXenes,which has a specific saturation magnetization of~0.26 emu/g and a Curie temperature of>353 K,is experimentally verified.The calculated electronic band structure implies that the semimetal Cr_(2)CT_(x)MXene has a band gap of 0.75 eV.This study opens new possibilities for the research and applications of industrial-scale manufacturing of MXenes and 2D semiconductors.展开更多
Self-intercalated van der Waals magnets,characterized by self-intercalating native atoms into van der Waals layered structures with intrinsic magnetism,exhibit a variety of novel physical properties.Here,using first-p...Self-intercalated van der Waals magnets,characterized by self-intercalating native atoms into van der Waals layered structures with intrinsic magnetism,exhibit a variety of novel physical properties.Here,using first-principles calculations and Monte Carlo simulations,we report a self-intercalated van der Waals ferromagnet,Cr_(3)Ge_(2)Te_(6),which has a high Curie temperature of 492 K.We find that Cr_(3)Ge_(2)Te_(6)is nearly half-metallic with a spin polarization reaching up to 90.9%.Due to the ferromagnetism and strong spin-orbit coupling effect in Cr_(3)Ge_(2)Te_(6),a large anomalous Hall conductivity of 138Ω^(-1)·cm^(-1)and 305Ω^(-1)·cm^(-1)can be realized when its magnetization is along its magnetic easy axis and hard axis,respectively.By doping electrons(holes)into Cr_(3)Ge_(2)Te_(6),these anomalous Hall conductivities can be increased up to 318Ω^(-1)·cm^(-1)(648Ω^(-1)·cm^(-1)).Interestingly,a five-layer Cr_(3)Ge_(2)Te_(6)thin film retains room-temperature ferromagnetism with a higher spin polarization and larger anomalous Hall conductivity.Our study demonstrates that Cr_(3)Ge_(2)Te_(6)is a novel room-temperature self-intercalated ferromagnet with high-spin polarization and large anomalous Hall conductivity,offering great opportunities for designing nano-scale electronic devices.展开更多
The self-intercalation of Cr into pristine two-dimensional(2D) van der Waals ferromagnetic CrTe_(2),which forms chromium tellurides(Cr_(x)Te_(2)),has garnered interest due to their remarkable magnetic characteristics ...The self-intercalation of Cr into pristine two-dimensional(2D) van der Waals ferromagnetic CrTe_(2),which forms chromium tellurides(Cr_(x)Te_(2)),has garnered interest due to their remarkable magnetic characteristics and the wide variety of chemical compositions available.Here,comprehensive basic characterization and magnetic studies are conducted on quasi-2D ferromagnetic Cr_(1.04)Te_(2) crystals.Measurements of the isothermal magnetization curves are conducted around the critical temperature to systematically investigate the critical behavior.Specifically,the critical exponents β=0.2399,γ=0.859,and δ=4.3498,as well as the Curie temperature T_(C)=249.56 K,are determined using various methods,including the modified Arrott plots,the Kouvel-Fisher method,the Widom scaling method,and the critical isotherm analysis.These results indicate that the tricritical mean-field model accurately represents the critical behavior of Cr_(1.04)Te_(2.A magnetic phase diagram with tricritical phenomenon is thus constructed.Further investigations confirm that the critical exponents obtained conform to the scalar equation near T_(C),indicating their self-consistency and reliability.Our work sheds light on the magnetic properties of quasi-2D Cr_(1.04)Te_(2),broadening the scope of the van der Waals crystals for developments of future spintronic devices operable at room temperature.展开更多
基金supported financially by the Beijing Natural Science Foundation(Nos.2212046,2234093,and L211001)the National Natural Science Foundation of China(Nos.51871011 and 51572017)+1 种基金the Research Fund for Commercialization of Major Scientific and Technological Achievements of Hebei Province(No.22281006Z)the Beijing Government Funds for the Constructive Project of Central Universities.
文摘Physical properties,such as electrochemical and electromagnetic properties,of two-dimensional MXenes can be improved by enhancing their stability.However,MXenes fabricated via acid etching contain defects,which affect their physical properties.In this study,a method to effectively remove Al residues using only water during MXene fabrication while maintaining structural stability is proposed.The fabrication and intercalation of MXenes are controlled via epitaxial self-intercalation of H_(2)O-etched Cr_(2)(AlLi)C.On the basis of this mechanism,the room-temperature ferromagnetism of two-dimensional few-layered Cr_(2)CT_(x)MXenes,which has a specific saturation magnetization of~0.26 emu/g and a Curie temperature of>353 K,is experimentally verified.The calculated electronic band structure implies that the semimetal Cr_(2)CT_(x)MXene has a band gap of 0.75 eV.This study opens new possibilities for the research and applications of industrial-scale manufacturing of MXenes and 2D semiconductors.
基金Project supported by the National Key R&D Program of China(Grant No.2022YFA1403301)the National Natural Science Foundation of China(Grant Nos.12474247 and 92165204)+1 种基金the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)the support from the Fundamental Research Funds for the Central Universities,Sun Yat-Sen University(Grant No.24qnpy108)。
文摘Self-intercalated van der Waals magnets,characterized by self-intercalating native atoms into van der Waals layered structures with intrinsic magnetism,exhibit a variety of novel physical properties.Here,using first-principles calculations and Monte Carlo simulations,we report a self-intercalated van der Waals ferromagnet,Cr_(3)Ge_(2)Te_(6),which has a high Curie temperature of 492 K.We find that Cr_(3)Ge_(2)Te_(6)is nearly half-metallic with a spin polarization reaching up to 90.9%.Due to the ferromagnetism and strong spin-orbit coupling effect in Cr_(3)Ge_(2)Te_(6),a large anomalous Hall conductivity of 138Ω^(-1)·cm^(-1)and 305Ω^(-1)·cm^(-1)can be realized when its magnetization is along its magnetic easy axis and hard axis,respectively.By doping electrons(holes)into Cr_(3)Ge_(2)Te_(6),these anomalous Hall conductivities can be increased up to 318Ω^(-1)·cm^(-1)(648Ω^(-1)·cm^(-1)).Interestingly,a five-layer Cr_(3)Ge_(2)Te_(6)thin film retains room-temperature ferromagnetism with a higher spin polarization and larger anomalous Hall conductivity.Our study demonstrates that Cr_(3)Ge_(2)Te_(6)is a novel room-temperature self-intercalated ferromagnet with high-spin polarization and large anomalous Hall conductivity,offering great opportunities for designing nano-scale electronic devices.
基金Project supported by the Natural Science Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY222170)Jiangsu Specially-Appointed Professor Program,and Natural Science Foundation of Universities of Jiangsu Province(Grant No.TJ219008)the support of the open research fund of Key Laboratory of Quantum Materials and Devices(Southeast University),Ministry of Education。
文摘The self-intercalation of Cr into pristine two-dimensional(2D) van der Waals ferromagnetic CrTe_(2),which forms chromium tellurides(Cr_(x)Te_(2)),has garnered interest due to their remarkable magnetic characteristics and the wide variety of chemical compositions available.Here,comprehensive basic characterization and magnetic studies are conducted on quasi-2D ferromagnetic Cr_(1.04)Te_(2) crystals.Measurements of the isothermal magnetization curves are conducted around the critical temperature to systematically investigate the critical behavior.Specifically,the critical exponents β=0.2399,γ=0.859,and δ=4.3498,as well as the Curie temperature T_(C)=249.56 K,are determined using various methods,including the modified Arrott plots,the Kouvel-Fisher method,the Widom scaling method,and the critical isotherm analysis.These results indicate that the tricritical mean-field model accurately represents the critical behavior of Cr_(1.04)Te_(2.A magnetic phase diagram with tricritical phenomenon is thus constructed.Further investigations confirm that the critical exponents obtained conform to the scalar equation near T_(C),indicating their self-consistency and reliability.Our work sheds light on the magnetic properties of quasi-2D Cr_(1.04)Te_(2),broadening the scope of the van der Waals crystals for developments of future spintronic devices operable at room temperature.
