Superconductivity and magnetism have been interesting topics in condensed mater physics and they have been studied experimentally and theoretically for many years. These two cooperative phenomena are antagonistic unti...Superconductivity and magnetism have been interesting topics in condensed mater physics and they have been studied experimentally and theoretically for many years. These two cooperative phenomena are antagonistic until the discovery of some rare earth ternary compounds that show the coexistence of superconductivity and magnetism. In some of the recently discovered iron-based layered superconductors, superconductivity and magnetism coexist. In the present work we examine the possibility of coexistence of antiferromagnetism and superconductivity in samarium arsenide oxide superconductor (SmAsO1-xFxFe). Using a model of the Hamiltonian and retarded double time Greens function formalism, we found expressions AFM order Parameter (η) and AFM transition temperature (Tm). We obtained the phase diagrams (Tc vs η) and(Tm vs η) to obtain the region where orders, i.e., superconductivity and AFM (antiferromagnetism), coexisted. The region under the intersection of the two merged graphs shows that superconductivity and AFM coexist in the system (SmAsO1-xFxFe).展开更多
The powder crystals of RMnO3（R=Er, Tm） with hexagonal and orthorhombic structures were prepared under hydrothermal conditions. The different structural phases of the title compounds were controllably formed from dif...The powder crystals of RMnO3（R=Er, Tm） with hexagonal and orthorhombic structures were prepared under hydrothermal conditions. The different structural phases of the title compounds were controllably formed from different kinds of precursors at different reaction temperatures. All of the samples were characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma analysis, and variable temperature magnetic susceptibility. Their structures were refined by Rietveld method from powder X-ray diffraction data. The measurement of magnetic behavior shows antiferromagnetic orderings at Neel temperatures around 80 and 40 K for the hexagonal and orthorhombic phases, respectively.展开更多
The valley index is a promising degree of freedom for information processing in electronic devices.However,the researches on valley polarization are mainly focused on ferromagnetic order,which breaks the time reversal...The valley index is a promising degree of freedom for information processing in electronic devices.However,the researches on valley polarization are mainly focused on ferromagnetic order,which breaks the time reversal symmetry simultaneously.Here,a novel paradigm for achieving stacking order modulated anomalous valley Hall(AVH)effect is proposed in antiferromagnetic monolayers.The paradigm involves the introduction and reversal of nonuniform potentials by modulating the position of substrate,to break the combined symmetry of spatial inversion and time reversal(PT symmetry)and achieve stacking-dependent valley spin splitting.Based on first-principles calculations,we discover spontaneous valley polarization in antiferromagnetic Cr_(2)CH_(2) MXene and stacking-dependent valley spin splitting in Cr_(2)CH_(2)/Sc_(2)CO_(2) heterostructure.Furthermore,switching the ferroelectric polarization of monolayer Sc_(2)CO_(2) results in a semiconductor-metal transition in Cr_(2)CH_(2)/Sc_(2)CO_(2),accompanied by the disappearance of valley physics.Our findings provide an alternative way to develop controllable valleytronics devices based on antiferromagnetic monolayers.展开更多
We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used ...We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.展开更多
Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared...Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.展开更多
We present a microscopic simulation of particles with time-dependent spins,where different interaction and density are considered.Ferromagnetism has been observed for the attractive spin-spin interaction,while antifer...We present a microscopic simulation of particles with time-dependent spins,where different interaction and density are considered.Ferromagnetism has been observed for the attractive spin-spin interaction,while antiferromagnetism and paramagnetism have been observed in different density region for the repulsive spin-spin interaction.The method developed here should be extended to include spin-color interaction into“color molecular dynamics”.展开更多
Noncollinear antiferromagnet Mn_(3)Sn has shown remarkable efficiency in charge-spin conversion,a novel magnetic spin Hall effect,and a stable topological antiferromagnetic state,which has resulted in great interest f...Noncollinear antiferromagnet Mn_(3)Sn has shown remarkable efficiency in charge-spin conversion,a novel magnetic spin Hall effect,and a stable topological antiferromagnetic state,which has resulted in great interest from researchers in the field of spin-orbit torque.Current research has primarily focused on the spin-orbit torque effect of epitaxially grown noncollinear antiferromagnet Mn_(3)Sn films.However,this method is not suitable for large-scale industrial preparation.In this study,amorphous Mn_(3)Sn films and Mn_(3)Sn/Py heterostructures were prepared using magnetron sputtering on silicon substrates.The spin-torque ferromagnetic resonance measurement demonstrated that only the conventional spin-orbit torque effect generated by in-plane polarized spin currents existed in the Mn_(3)Sn/Py heterostructure,with a spin-orbit torque efficiency of 0.016.Additionally,we prepared the perpendicular magnetized Mn_(3)Sn/CoTb heterostructure based on amorphous Mn_(3)Sn film,where the spin-orbit torque driven perpendicular magnetization switching was achieved with a lower critical switching current density(3.9×10^(7)A/cm^(2))compared to Ta/CoTb heterostructure.This research reveals the spin-orbit torque effect of amorphous Mn_(3)Sn films and establishes a foundation for further advancement in the practical application of Mn_(3)Sn materials in spintronic devices.展开更多
Electron-phonon interactions and electron-electron correlations represent two crucial facets of condensed matter physics.For instance,in a half-filled spin-1/2 anti-ferromagnetic chain,the lattice dimerization induced...Electron-phonon interactions and electron-electron correlations represent two crucial facets of condensed matter physics.For instance,in a half-filled spin-1/2 anti-ferromagnetic chain,the lattice dimerization induced by electron-nucleus interaction can be intensified by onsite Coulomb repulsion,resulting in a spin-Peierls state.Through first-principles calculations and crystal structure prediction methods,we have identified that under mild pressures,potassium and ammonia can form stable compounds:R3m K(NH_(3))_(2),Pm3 m K(NH_(3))_(2),and Cm K_(2)(NH_(3))_(3).Our predictions suggest that the R3 m K(NH_(3))_(2)exhibits electride characteristics,marked by the formation of interstitial anionic electrons(IAEs)in the interlayer space.These IAEs are arranged in quasi-two-dimensional triangular arrays.With increasing pressure,the electronic van-Hove singularity shifts toward the Fermi level,resulting in an augmented density of states and the onset of both Peierls and magnetic instabilities.Analyzing these instabilities,we determine that the ground state of the R3 m K(NH_(3))_(2)is the dimerized P2_(1)/m phase with zigzag-type anti-ferromagnetic IAEs.This state can be described by the triangular-lattice antiferromagnetic Heisenberg model with modulated magnetic interactions.Furthermore,we unveil the coexistence and positive interplay between magnetic and Peierls instability,constituting a scenario of spin-Peierls instability unprecedented in realistic 2D materials,particularly involving IAEs.This work provides valuable insights into the coupling of IAEs with the adjacent lattice and their spin correlations in quantum materials.展开更多
The crystallographic and magnetic properties are presented for van der Waals antiferromagnetic FePS_3. High-quality single crystals of millimeter size have been successfully synthesized through the chemical vapor tran...The crystallographic and magnetic properties are presented for van der Waals antiferromagnetic FePS_3. High-quality single crystals of millimeter size have been successfully synthesized through the chemical vapor transport method. The layered structure and cleavability of the compound are apparent, which are beneficial for a potential exploration of the interesting low dimensional magnetism, as well as for incorporation of FePS_3 into van der Waals heterostructures. For the sake of completeness, we have measured both direct current(dc) and alternating current(ac) magnetic susceptibility.The paramagnetic to antiferromagnetic transition occurs at approximately T_N 115 K. The effective moment is larger than the spin-only effective moment, suggesting that an orbital contribution to the total angular momentum of the Fe^(2+) could be present. The ac susceptibility is independent of frequency, which means that the spin freezing effect is excluded.Strong anisotropy of out-of-plane and in-plane susceptibility has been shown, demonstrating the Ising-type magnetic order in FePS_3 system.展开更多
Iron-based superconductors namely Sr(Fe1.8Co0.2)As1.8 (FeAs1.8) and Sr(Fe1.8Co0.2)As1.85 (FeAs1.85) with As deficiency are prepared by solid-state reaction. X-ray diffraction reveals that the polycrystalline phase for...Iron-based superconductors namely Sr(Fe1.8Co0.2)As1.8 (FeAs1.8) and Sr(Fe1.8Co0.2)As1.85 (FeAs1.85) with As deficiency are prepared by solid-state reaction. X-ray diffraction reveals that the polycrystalline phase forms in the studied samples, identical to typical SrFe2As2 (122) matrix. Resistive and magnetic measurements show that the superconducting transition temperatures (Tc) are about 19 K for both FeAs1.8 and FeAs1.85. Compared with the performances of typical iron-based 122 superconductors arising from Co doping, the present samples show the suppressed superconductivity. Moreover, the antiferromagnetic (AFM) phase correlated with spin-density-wave (SDW) is reduced as well. The AFM transition temperature decreases to 122 K for FeAs1.85, while such a phase transition is absent at all for FeAs1.8, one sample with less As, implying that the existence of SDW and antiferromagnetism is more sensitive to As content.展开更多
The structures,grain sizes and magnetism were analyzed and computed for three typical samples:the stock of polycrystalline metal Gd(sample 1),the bulk nanocrystalline Gd prepared by spark plasma sintering(SPS) techniq...The structures,grain sizes and magnetism were analyzed and computed for three typical samples:the stock of polycrystalline metal Gd(sample 1),the bulk nanocrystalline Gd prepared by spark plasma sintering(SPS) technique and subjected to the annealing process of 623 K for 0.5 h(sample 2) and the bulk nanocrystalline Gd prepared by the SPS technique at 573 K(sample 3).The computation results indicated that the sample 3 had the efficiency of space filling up to 99.38%.The computation results of magnetization i...展开更多
文摘Superconductivity and magnetism have been interesting topics in condensed mater physics and they have been studied experimentally and theoretically for many years. These two cooperative phenomena are antagonistic until the discovery of some rare earth ternary compounds that show the coexistence of superconductivity and magnetism. In some of the recently discovered iron-based layered superconductors, superconductivity and magnetism coexist. In the present work we examine the possibility of coexistence of antiferromagnetism and superconductivity in samarium arsenide oxide superconductor (SmAsO1-xFxFe). Using a model of the Hamiltonian and retarded double time Greens function formalism, we found expressions AFM order Parameter (η) and AFM transition temperature (Tm). We obtained the phase diagrams (Tc vs η) and(Tm vs η) to obtain the region where orders, i.e., superconductivity and AFM (antiferromagnetism), coexisted. The region under the intersection of the two merged graphs shows that superconductivity and AFM coexist in the system (SmAsO1-xFxFe).
基金Supported by the National Natural Science Foundation of China(Nos.20631010 and 20771042)
文摘The powder crystals of RMnO3（R=Er, Tm） with hexagonal and orthorhombic structures were prepared under hydrothermal conditions. The different structural phases of the title compounds were controllably formed from different kinds of precursors at different reaction temperatures. All of the samples were characterized by powder X-ray diffraction, scanning electron microscopy, inductively coupled plasma analysis, and variable temperature magnetic susceptibility. Their structures were refined by Rietveld method from powder X-ray diffraction data. The measurement of magnetic behavior shows antiferromagnetic orderings at Neel temperatures around 80 and 40 K for the hexagonal and orthorhombic phases, respectively.
基金supported by the National Key Research and Development Program of China(2022YFB3807200)National Natural Science Foundation of China(52222101).
文摘The valley index is a promising degree of freedom for information processing in electronic devices.However,the researches on valley polarization are mainly focused on ferromagnetic order,which breaks the time reversal symmetry simultaneously.Here,a novel paradigm for achieving stacking order modulated anomalous valley Hall(AVH)effect is proposed in antiferromagnetic monolayers.The paradigm involves the introduction and reversal of nonuniform potentials by modulating the position of substrate,to break the combined symmetry of spatial inversion and time reversal(PT symmetry)and achieve stacking-dependent valley spin splitting.Based on first-principles calculations,we discover spontaneous valley polarization in antiferromagnetic Cr_(2)CH_(2) MXene and stacking-dependent valley spin splitting in Cr_(2)CH_(2)/Sc_(2)CO_(2) heterostructure.Furthermore,switching the ferroelectric polarization of monolayer Sc_(2)CO_(2) results in a semiconductor-metal transition in Cr_(2)CH_(2)/Sc_(2)CO_(2),accompanied by the disappearance of valley physics.Our findings provide an alternative way to develop controllable valleytronics devices based on antiferromagnetic monolayers.
基金Project supported by the Natural Science Basic Research Program of Shaanxi(Program Nos.2023KJXX-064 and 2021JQ-748)the National Natural Science Foundation of China(Grant Nos.11804213 and 12174238)Scientific Research Foundation of Shaanxi University of Technology(Grant No.SLGRCQD2006).
文摘We study the coexistence of antiferromagnetism and unconventional superconductivity on the Creutz lattice which shows strictly flat bands in the noninteracting regime.The famous renormalized mean-field theory is used to deal with strong electron-electron repulsive Hubbard interaction in the effective low-energy t-J model,the superfluid weight of the unconventional superconducting state has been calculated via the linear response theory.An unconventional superconducting state with both spin-singlet and staggered spin-triplet pairs emerges beyond a critical antiferromagnetic coupling interaction,while antiferromagnetism accompanies this state.The superconducting state with only spin-singlet pairs is dominant with paramagnetic phase.The A phase is analogous to the pseudogap phase,which shows that electrons go to form pairs but do not cause a supercurrent.We also show the superfluid behavior of the unconventional superconducting state and its critical temperature.It is proven directly that the flat band can effectively raise the critical temperature of superconductivity.It is implementable to simulate and control strongly-correlated electrons'behavior on the Creutz lattice in the ultracold atoms experiment or other artificial structures.Our results may help the understanding of the interplay between unconventional superconductivity and magnetism.
基金Project supported by the open research fund of Songshan Lake Materials Laboratory(Grant No.2021SLABFN11)the National Natural Science Foundation of China(Grant Nos.U2130101 and 92165204)+5 种基金Natural Science Foundation of Guangdong Province(Grant No.2022A1515010035)Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201011798)the Open Project of Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008)the Open Project of Key Laboratory of Optoelectronic Materials and Technologies(Grant No.OEMT-2023-ZTS-01)the National Key R&D Program of China(Grant Nos.2023YFF0718400 and 2023YFA1406500)(national)college students innovation and entrepreneurship training program,Sun Yat-sen University(Grant No.202310359).
文摘Systemically angular and planar transport investigations are performed in layered antiferromagnetic(AF)V_(5)S_(8).In this AF system,obvious anomalous Hall effect(AHE)is observed with a large Hall angle of 0.1 compared to that in ferromagnetic(FM)system.It can persist to the temperatures above AF transition and exhibit strong angular field dependence.The phase diagram reveals various magnetic states by rotating the applied field.By analyzing the anisotropic transport behavior,magnon contributions are revealed and exhibit obvious angular dependence with a spin-flop vanishing line.The observed prominent planar Hall effect and anisotropic magnetoresisitivity exhibit two-fold systematical angular dependent oscillations.These behaviors are attributed to the scattering from spin–orbital coupling instead of nontrivial topological origin.Our results reveal anisotropic interactions of magnetism and electron in V5S8,suggesting potential opportunities for the AF spintronic sensor and devices.
基金supported by JSPS KAKENHI Grant Number 20K03951.
文摘We present a microscopic simulation of particles with time-dependent spins,where different interaction and density are considered.Ferromagnetism has been observed for the attractive spin-spin interaction,while antiferromagnetism and paramagnetism have been observed in different density region for the repulsive spin-spin interaction.The method developed here should be extended to include spin-color interaction into“color molecular dynamics”.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFE0103300)the National Natural Science Foundation of China(Grant No.12274119)+1 种基金the Natural Science Foundation of Hubei Province(Grant No.2022CFA088)the Open Research Fund of Songshan Lake Materials Laboratory(Grant No.2022SLABFN04).
文摘Noncollinear antiferromagnet Mn_(3)Sn has shown remarkable efficiency in charge-spin conversion,a novel magnetic spin Hall effect,and a stable topological antiferromagnetic state,which has resulted in great interest from researchers in the field of spin-orbit torque.Current research has primarily focused on the spin-orbit torque effect of epitaxially grown noncollinear antiferromagnet Mn_(3)Sn films.However,this method is not suitable for large-scale industrial preparation.In this study,amorphous Mn_(3)Sn films and Mn_(3)Sn/Py heterostructures were prepared using magnetron sputtering on silicon substrates.The spin-torque ferromagnetic resonance measurement demonstrated that only the conventional spin-orbit torque effect generated by in-plane polarized spin currents existed in the Mn_(3)Sn/Py heterostructure,with a spin-orbit torque efficiency of 0.016.Additionally,we prepared the perpendicular magnetized Mn_(3)Sn/CoTb heterostructure based on amorphous Mn_(3)Sn film,where the spin-orbit torque driven perpendicular magnetization switching was achieved with a lower critical switching current density(3.9×10^(7)A/cm^(2))compared to Ta/CoTb heterostructure.This research reveals the spin-orbit torque effect of amorphous Mn_(3)Sn films and establishes a foundation for further advancement in the practical application of Mn_(3)Sn materials in spintronic devices.
基金financial support from the National Key R&D Program of China(2022YFA1403201)the National Natural Science Foundation of China(12125404,11974162,and 11834006)the Fundamental Research Funds for the Central Universities。
文摘Electron-phonon interactions and electron-electron correlations represent two crucial facets of condensed matter physics.For instance,in a half-filled spin-1/2 anti-ferromagnetic chain,the lattice dimerization induced by electron-nucleus interaction can be intensified by onsite Coulomb repulsion,resulting in a spin-Peierls state.Through first-principles calculations and crystal structure prediction methods,we have identified that under mild pressures,potassium and ammonia can form stable compounds:R3m K(NH_(3))_(2),Pm3 m K(NH_(3))_(2),and Cm K_(2)(NH_(3))_(3).Our predictions suggest that the R3 m K(NH_(3))_(2)exhibits electride characteristics,marked by the formation of interstitial anionic electrons(IAEs)in the interlayer space.These IAEs are arranged in quasi-two-dimensional triangular arrays.With increasing pressure,the electronic van-Hove singularity shifts toward the Fermi level,resulting in an augmented density of states and the onset of both Peierls and magnetic instabilities.Analyzing these instabilities,we determine that the ground state of the R3 m K(NH_(3))_(2)is the dimerized P2_(1)/m phase with zigzag-type anti-ferromagnetic IAEs.This state can be described by the triangular-lattice antiferromagnetic Heisenberg model with modulated magnetic interactions.Furthermore,we unveil the coexistence and positive interplay between magnetic and Peierls instability,constituting a scenario of spin-Peierls instability unprecedented in realistic 2D materials,particularly involving IAEs.This work provides valuable insights into the coupling of IAEs with the adjacent lattice and their spin correlations in quantum materials.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11404169,51602159,and 11704196)the Scientific Research Foundation of Nanjing University of Posts&Telecommunications,China(Grant Nos.NY217043 and NY218021)the Postgraduate Research&Practice Innovation Program of Jiangsu Province,China(Grant Nos.KYCX17 0754 and SJCX18 0287)
文摘The crystallographic and magnetic properties are presented for van der Waals antiferromagnetic FePS_3. High-quality single crystals of millimeter size have been successfully synthesized through the chemical vapor transport method. The layered structure and cleavability of the compound are apparent, which are beneficial for a potential exploration of the interesting low dimensional magnetism, as well as for incorporation of FePS_3 into van der Waals heterostructures. For the sake of completeness, we have measured both direct current(dc) and alternating current(ac) magnetic susceptibility.The paramagnetic to antiferromagnetic transition occurs at approximately T_N 115 K. The effective moment is larger than the spin-only effective moment, suggesting that an orbital contribution to the total angular momentum of the Fe^(2+) could be present. The ac susceptibility is independent of frequency, which means that the spin freezing effect is excluded.Strong anisotropy of out-of-plane and in-plane susceptibility has been shown, demonstrating the Ising-type magnetic order in FePS_3 system.
基金National Natural Science Foundation of China (50702033, 10774098)Ministry of Science and Technology of China (2006CB601005,2009AA03Z204)+1 种基金Shanghai Leading Academic Discipline Project (S30105)Science and Technology Commission of Shanghai Municipality (08521101502)
文摘Iron-based superconductors namely Sr(Fe1.8Co0.2)As1.8 (FeAs1.8) and Sr(Fe1.8Co0.2)As1.85 (FeAs1.85) with As deficiency are prepared by solid-state reaction. X-ray diffraction reveals that the polycrystalline phase forms in the studied samples, identical to typical SrFe2As2 (122) matrix. Resistive and magnetic measurements show that the superconducting transition temperatures (Tc) are about 19 K for both FeAs1.8 and FeAs1.85. Compared with the performances of typical iron-based 122 superconductors arising from Co doping, the present samples show the suppressed superconductivity. Moreover, the antiferromagnetic (AFM) phase correlated with spin-density-wave (SDW) is reduced as well. The AFM transition temperature decreases to 122 K for FeAs1.85, while such a phase transition is absent at all for FeAs1.8, one sample with less As, implying that the existence of SDW and antiferromagnetism is more sensitive to As content.
基金supported by the National Basic Research Program of China (2006CB705601)the National Natural Science Foundation of China (50771002)
文摘The structures,grain sizes and magnetism were analyzed and computed for three typical samples:the stock of polycrystalline metal Gd(sample 1),the bulk nanocrystalline Gd prepared by spark plasma sintering(SPS) technique and subjected to the annealing process of 623 K for 0.5 h(sample 2) and the bulk nanocrystalline Gd prepared by the SPS technique at 573 K(sample 3).The computation results indicated that the sample 3 had the efficiency of space filling up to 99.38%.The computation results of magnetization i...
