Spin-density(charge)separation,marked by distinct propagation velocities of spin and density excitations,epitomizes strong correlations,historically confined to one-dimensional(1D)systems.The recent experimental work ...Spin-density(charge)separation,marked by distinct propagation velocities of spin and density excitations,epitomizes strong correlations,historically confined to one-dimensional(1D)systems.The recent experimental work of Dhar et al(2025 Nature 64253),using a weakly interacting 3D Bose-Einstein condensate of^(133)Cs atoms confined in a 2D optical lattice to realize spin-density separation and demonstrate boson anyonization,motivates a deeper exploration into how dimensionality and interactions govern quantum correlations.In this work,we investigate this in two-component bosonic mixtures with finite-range interactions,probing 1D and 3D dynamics.Using path integral effective field theory within the one-loop approximation,we derive analytical expressions for zero-temperature ground-state energy and quantum depletion,seamlessly recovering contact interaction results in the contact limit.By crafting an effective action for decoupled density and spin modes,we compute dynamic structure factors(DSFs),revealing how finite-range interactions sculpt spin-density separation.A pivotal finding is the dimensionality-driven divergence in DSF peak dynamics:in 1D,peaks ascend to higher frequencies with increasing interaction strength,yielding sharp responses;in 3D,peaks descend to lower frequencies,with broader density wave profiles.These insights highlight dimensionality's critical role in collective excitations and provide a robust theoretical blueprint for probing interaction-driven quantum phenomena via Bragg spectroscopy,paving new pathways for the exploration of dimensionally tuned quantum correlations in ultracold quantum gases.展开更多
Our recent scanning tunneling microscopy （STM） studies of the NaFelxCoxAs phase diagram over a wide range of dopings and temperatures are reviewed. Similar to the high-Tc cuprates, the iron-based superconductors lie...Our recent scanning tunneling microscopy （STM） studies of the NaFelxCoxAs phase diagram over a wide range of dopings and temperatures are reviewed. Similar to the high-Tc cuprates, the iron-based superconductors lie in close proximity to a magnetically ordered phase. Therefore, it is widely believed that magnetic interactions or fluctuations play an important role in triggering their Cooper pairings. Among the key issues regarding the electronic phase diagram are the properties of the parent spin density wave （SDW） phase and the superconducting （SC） phase, as well as the interplay between them. The NaFe l-xCoxAs is an ideal system for resolving these issues due to its rich electronic phases and the charge-neutral cleaved surface. In our recent work, we directly observed the SDW gap in the parent state, and it exhibits unconventional features that are incompatible with the simple Fermi surface nesting picture. The optimally doped sample has a single SC gap, but in the underdoped regime we directly viewed the microscopic coexistence of the SDW and SC orders, which compete with each other. In the overdoped regime we observed a novel pseudogap-like feature that coexists with supercon- ductivity in the ground state, persists well into the normal state, and shows great spatial variations. The rich electronic structures across the phase diagram of NaFel_xCoxAs revealed here shed important new light for defining microscopic models of the iron-based superconductors. In particular, we argue that both the itinerant electrons and local moments should be considered on an equal footing in a realistic model.展开更多
The half-filled Hubbard chains with the Fibonacci and Harper modulating site potentials are studied in a selfconsistent mean-field approximation. A new order parameter is introduced to describe a charge density order....The half-filled Hubbard chains with the Fibonacci and Harper modulating site potentials are studied in a selfconsistent mean-field approximation. A new order parameter is introduced to describe a charge density order. We also calculate the von Neumann entropy of the ground state. The results show that the von Neumann entropy can identify a CDW/SDW （charge density wave/spin density wave） transition for quasiperiodic models.展开更多
Charge and spin orders are intimately related to superconductivity in copper oxide superconductors.Elucidation of the competing orders in various nickel oxide compounds is crucial,given the fact that superconductivity...Charge and spin orders are intimately related to superconductivity in copper oxide superconductors.Elucidation of the competing orders in various nickel oxide compounds is crucial,given the fact that superconductivity has been discovered in Nd_(0.8)Sr_(0.2)NiO_(2)films.Herein,we report structural,electronic transport,magnetic,and thermodynamic characterizations of single crystals of La_(3)Ni_(2)O_(7)and La_(3)Ni_(2)O_(6).La_(3)Ni_(2)O_(7)is metallic with mixed Ni^(2+)and Ni^(3+)valent states.Resistivity measurements yield two transition-like kinks at~110 and 153 K.The kink at 153 K is further revealed from magnetization and specific heat measurements,indicative of the formation of charge and spin density waves.La_(3)Ni_(2)O_(6)single crystals obtained from the topochemical reduction of La_(3)Ni_(2)O_(7)are insulating and show an anomaly at~176 K on magnetic susceptibility.The transition-like behaviors of La_(3)Ni_(2)O_(7)and La_(3)Ni_(2)O_(6)are analogous to those observed in La_(4)Ni_(3)O_(10) and La_(4)Ni_(3)O_(8),suggesting that charge and spin density waves are a common feature in the ternary La-Ni-O system with mixed-valent states of nickel.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12574301)the Zhejiang Provincial Natural Science Foundation(Grant No.LZ25A040004)。
文摘Spin-density(charge)separation,marked by distinct propagation velocities of spin and density excitations,epitomizes strong correlations,historically confined to one-dimensional(1D)systems.The recent experimental work of Dhar et al(2025 Nature 64253),using a weakly interacting 3D Bose-Einstein condensate of^(133)Cs atoms confined in a 2D optical lattice to realize spin-density separation and demonstrate boson anyonization,motivates a deeper exploration into how dimensionality and interactions govern quantum correlations.In this work,we investigate this in two-component bosonic mixtures with finite-range interactions,probing 1D and 3D dynamics.Using path integral effective field theory within the one-loop approximation,we derive analytical expressions for zero-temperature ground-state energy and quantum depletion,seamlessly recovering contact interaction results in the contact limit.By crafting an effective action for decoupled density and spin modes,we compute dynamic structure factors(DSFs),revealing how finite-range interactions sculpt spin-density separation.A pivotal finding is the dimensionality-driven divergence in DSF peak dynamics:in 1D,peaks ascend to higher frequencies with increasing interaction strength,yielding sharp responses;in 3D,peaks descend to lower frequencies,with broader density wave profiles.These insights highlight dimensionality's critical role in collective excitations and provide a robust theoretical blueprint for probing interaction-driven quantum phenomena via Bragg spectroscopy,paving new pathways for the exploration of dimensionally tuned quantum correlations in ultracold quantum gases.
基金supported by the National Basic Research Program of China(Grant Nos.2009CB929400 and 2010CB923003)
文摘Our recent scanning tunneling microscopy （STM） studies of the NaFelxCoxAs phase diagram over a wide range of dopings and temperatures are reviewed. Similar to the high-Tc cuprates, the iron-based superconductors lie in close proximity to a magnetically ordered phase. Therefore, it is widely believed that magnetic interactions or fluctuations play an important role in triggering their Cooper pairings. Among the key issues regarding the electronic phase diagram are the properties of the parent spin density wave （SDW） phase and the superconducting （SC） phase, as well as the interplay between them. The NaFe l-xCoxAs is an ideal system for resolving these issues due to its rich electronic phases and the charge-neutral cleaved surface. In our recent work, we directly observed the SDW gap in the parent state, and it exhibits unconventional features that are incompatible with the simple Fermi surface nesting picture. The optimally doped sample has a single SC gap, but in the underdoped regime we directly viewed the microscopic coexistence of the SDW and SC orders, which compete with each other. In the overdoped regime we observed a novel pseudogap-like feature that coexists with supercon- ductivity in the ground state, persists well into the normal state, and shows great spatial variations. The rich electronic structures across the phase diagram of NaFel_xCoxAs revealed here shed important new light for defining microscopic models of the iron-based superconductors. In particular, we argue that both the itinerant electrons and local moments should be considered on an equal footing in a realistic model.
基金supported by the National Natural Science Foundation of China (Grant Nos 90203009, 10175035 and 10674072)the Specialized Research Fund for the Doctoral Programme (SRFDP) of Higher Education of China (Grant No 20060319007)the Foundation for outstanding Young Teacher of Ministry of Education of China
文摘The half-filled Hubbard chains with the Fibonacci and Harper modulating site potentials are studied in a selfconsistent mean-field approximation. A new order parameter is introduced to describe a charge density order. We also calculate the von Neumann entropy of the ground state. The results show that the von Neumann entropy can identify a CDW/SDW （charge density wave/spin density wave） transition for quasiperiodic models.
基金supported by the National Natural Science Foundation of China(Grant Nos.12174454,11904414,11904416,and U2130101)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515120015)+1 种基金the Guangzhou Basic and Applied Basic Research Foundation(Grant No.202201011123)the National Key Research and Development Program of China(Grant Nos.2019YFA0705702,2020YFA0406003,2021YFA1400401,and 2021YFA0718900)。
文摘Charge and spin orders are intimately related to superconductivity in copper oxide superconductors.Elucidation of the competing orders in various nickel oxide compounds is crucial,given the fact that superconductivity has been discovered in Nd_(0.8)Sr_(0.2)NiO_(2)films.Herein,we report structural,electronic transport,magnetic,and thermodynamic characterizations of single crystals of La_(3)Ni_(2)O_(7)and La_(3)Ni_(2)O_(6).La_(3)Ni_(2)O_(7)is metallic with mixed Ni^(2+)and Ni^(3+)valent states.Resistivity measurements yield two transition-like kinks at~110 and 153 K.The kink at 153 K is further revealed from magnetization and specific heat measurements,indicative of the formation of charge and spin density waves.La_(3)Ni_(2)O_(6)single crystals obtained from the topochemical reduction of La_(3)Ni_(2)O_(7)are insulating and show an anomaly at~176 K on magnetic susceptibility.The transition-like behaviors of La_(3)Ni_(2)O_(7)and La_(3)Ni_(2)O_(6)are analogous to those observed in La_(4)Ni_(3)O_(10) and La_(4)Ni_(3)O_(8),suggesting that charge and spin density waves are a common feature in the ternary La-Ni-O system with mixed-valent states of nickel.
