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
Functionalized two-dimensional materials with multiferroicity are highly desired to be next-generation electronic devices.Here we theoretically predict a family of Janus vanadium dichalcogenides VXX'(X/X'=S,Se...Functionalized two-dimensional materials with multiferroicity are highly desired to be next-generation electronic devices.Here we theoretically predict a family of Janus vanadium dichalcogenides VXX'(X/X'=S,Se,Te)monolayers with multiferroic properties,combing ferromagnetism,ferroelasticity and piezoelectricity.Due to the unpaired electrons on the V atom,the Janus VXX'monolayers have intrinsic long-range ferromagnetic orders.Particularly,the Curie temperature of 1T-VSeTe monolayer is up to 100 K,which is greatly higher than 2D 1T-VSe2 and 1T-VTe2.Furthermore,the six Janus VXX'monolayers have similar crater-like ferroelastic switching curves.Compared to black phosphorus,2H-VSSe monolayer has the similar ferroelastic switching signal and 4 times lower energy barrier.In addition,the out-of-plane piezoelectricity induced by the structure asymmetry in the vertical direction gives the 2H-VXX'monolayers the potential to be piezoelectric materials.It is found that a built-in electric field in the vertical direction due to the different electronegativity values of chalcogen atoms induces the changes of electronic structures,which leads to the appearance of three different types of band gaps in the three H-phase structures.Recently,the experimental growth of the Janus MoSSe monolayers and the electrochemical exfoliation of ferromagnetic monolayered VSe2 make the Janus VXX'monolayers possibly fabricated in experiments.展开更多
This paper provides a survey on symbolic computational approaches for the analysis of qualitative behaviors of systems of ordinary differential equations,focusing on symbolic and algebraic analysis for the local stabi...This paper provides a survey on symbolic computational approaches for the analysis of qualitative behaviors of systems of ordinary differential equations,focusing on symbolic and algebraic analysis for the local stability and bifurcation of limit cycles in the neighborhoods of equilibria and periodic orbits of the systems,with a highlight on applications to computational biology.展开更多
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.
基金Supported by the National Natural Science Foundation of China(Grant Nos.61704083,61605087 and 61874060)the Natural Science Foundation of Jiangsu Province(Grant Nos.BK20160881 and BK20181388)the Foundation of Nanjing University of Posts and Telecommunications(Grant No.NY219030).
文摘Functionalized two-dimensional materials with multiferroicity are highly desired to be next-generation electronic devices.Here we theoretically predict a family of Janus vanadium dichalcogenides VXX'(X/X'=S,Se,Te)monolayers with multiferroic properties,combing ferromagnetism,ferroelasticity and piezoelectricity.Due to the unpaired electrons on the V atom,the Janus VXX'monolayers have intrinsic long-range ferromagnetic orders.Particularly,the Curie temperature of 1T-VSeTe monolayer is up to 100 K,which is greatly higher than 2D 1T-VSe2 and 1T-VTe2.Furthermore,the six Janus VXX'monolayers have similar crater-like ferroelastic switching curves.Compared to black phosphorus,2H-VSSe monolayer has the similar ferroelastic switching signal and 4 times lower energy barrier.In addition,the out-of-plane piezoelectricity induced by the structure asymmetry in the vertical direction gives the 2H-VXX'monolayers the potential to be piezoelectric materials.It is found that a built-in electric field in the vertical direction due to the different electronegativity values of chalcogen atoms induces the changes of electronic structures,which leads to the appearance of three different types of band gaps in the three H-phase structures.Recently,the experimental growth of the Janus MoSSe monolayers and the electrochemical exfoliation of ferromagnetic monolayered VSe2 make the Janus VXX'monolayers possibly fabricated in experiments.
基金The work was partially supported by the National Natural Science Foundation of China(12101032,12131004 and 11601023)Ministry of Science and Technology of China(2021YFA1003600)Beijing Natural Science Foundation(1212005).
文摘This paper provides a survey on symbolic computational approaches for the analysis of qualitative behaviors of systems of ordinary differential equations,focusing on symbolic and algebraic analysis for the local stability and bifurcation of limit cycles in the neighborhoods of equilibria and periodic orbits of the systems,with a highlight on applications to computational biology.
