Understanding the formation of novel pair density waves(PDWs)in strongly correlated electronic systems remains extremely challenging.Recent mean-field studies suggest that PDW phases may arise in strong-coupling multi...Understanding the formation of novel pair density waves(PDWs)in strongly correlated electronic systems remains extremely challenging.Recent mean-field studies suggest that PDW phases may arise in strong-coupling multiband superconductors by the quantum geometric properties of paired electrons.However,scrutiny through sophisticated many-body calculations has been lacking.Employing large-scale density matrix renormalization group calculations,we obtain in the strong-coupling regime phase diagram as a function of doping concentration and a tuning interaction parameter for a simple two-orbital model that incorporates quantum geometric effects.The phase diagram reveals a robust PDW phase spanning a broad range of parameters,characterized by a Luttinger parameter K_(sc)~0.3 and the absence of coexisting competing spin or charge density wave orders.The observed pairing field configuration aligns with the phenomenological understanding that quantum geometry can promote PDW formation.Our study provides the most compelling numerical evidence to date for quantum-geometry-facilitated intrinsic PDW order in strongly correlated systems,paving the way for further exploration of novel PDW orders and quantum geometric effects in such systems.展开更多
Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carri...Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carries over to the superconducting state,which receives a geometric contribution to the superfluid weight.In this paper,we show that this contribution could become negative under certain appropriate circumstances.This may facilitate the stabilization of Cooper pairings with real space phase modulation,i.e.,the pair density wave order,as we demonstrate through two-orbital model Bogoliubov de-Gennes mean-field calculations.The quantum geometric effect therefore constitutes an intrinsic mechanism for the formation of such a novel phase of matter in the absence of external magnetic field.展开更多
Recently,the discovery of vanadium-based kagome metal AV_(3)Sb_(5)(A=K,Rb,Cs)has attracted great interest in the field of superconductivity due to the coexistence of superconductivity,non-trivial surface state and mul...Recently,the discovery of vanadium-based kagome metal AV_(3)Sb_(5)(A=K,Rb,Cs)has attracted great interest in the field of superconductivity due to the coexistence of superconductivity,non-trivial surface state and multiple density waves.In this topical review,we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV_(3)Sb_(5).We start with the unconventional charge density waves,which are thought to correlate to the time-reversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV_(3)Sb_(5).Then we discuss the superconductivity and the topological band structure.Next,we review the competition between the superconductivity and charge density waves under different conditions of pressure,chemical doping,thickness,and strains.Finally,the experimental evidence of pseudogap pair density wave is discussed.展开更多
The superconducting state typically favors a uniform spatial distribution akin to ferromagnetism.Nevertheless,the pair-densitywave state exhibits sign changes in the pairing order,leading to potential frustrations in ...The superconducting state typically favors a uniform spatial distribution akin to ferromagnetism.Nevertheless,the pair-densitywave state exhibits sign changes in the pairing order,leading to potential frustrations in phase coherence.We propose a mechanism to the sextetting order stemming from the frustrations in the phase coherence of a pair-density-wave state,whose spatial modulation manifests a vortex-antivortex honeycomb lattice.The classical ground state configurations are mapped to Baxter's three-coloring model,revealing a macroscopic degeneracy accompanied by extensive entropy.The phase coherence problem intertwines the U(1)phases and the vorticity variables.While the resultant color and phase fluctuations suppress the pair-densitywave order,they maintain the sextetting order above the superconducting transition temperature(T_(c)).The 1/3-fractional vortex emerges as the fundamental topological defect in the sextetting order.This novel mechanism of frustrated superconductivity provides an alternative explanation for the experimental observed fractional oscillations in CsV_(3)Sb_(5).展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.12374042,and 11904155)the Guangdong Science and Technology Department(Grant No.2022A1515011948)the Shenzhen Science and Technology Program(Grant No.KQTD20200820113010023).
文摘Understanding the formation of novel pair density waves(PDWs)in strongly correlated electronic systems remains extremely challenging.Recent mean-field studies suggest that PDW phases may arise in strong-coupling multiband superconductors by the quantum geometric properties of paired electrons.However,scrutiny through sophisticated many-body calculations has been lacking.Employing large-scale density matrix renormalization group calculations,we obtain in the strong-coupling regime phase diagram as a function of doping concentration and a tuning interaction parameter for a simple two-orbital model that incorporates quantum geometric effects.The phase diagram reveals a robust PDW phase spanning a broad range of parameters,characterized by a Luttinger parameter K_(sc)~0.3 and the absence of coexisting competing spin or charge density wave orders.The observed pairing field configuration aligns with the phenomenological understanding that quantum geometry can promote PDW formation.Our study provides the most compelling numerical evidence to date for quantum-geometry-facilitated intrinsic PDW order in strongly correlated systems,paving the way for further exploration of novel PDW orders and quantum geometric effects in such systems.
基金supported by the National Natural Science Foundation of China(Grant No.11904155)the Guangdong Provincial Key Laboratory(Grant No.2019B121203002)+1 种基金the Guangdong Science and Technology Department(Grant No.2022A1515011948)the Shenzhen Science and Technology Program(Grant No.KQTD20200820113010023)。
文摘Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carries over to the superconducting state,which receives a geometric contribution to the superfluid weight.In this paper,we show that this contribution could become negative under certain appropriate circumstances.This may facilitate the stabilization of Cooper pairings with real space phase modulation,i.e.,the pair density wave order,as we demonstrate through two-orbital model Bogoliubov de-Gennes mean-field calculations.The quantum geometric effect therefore constitutes an intrinsic mechanism for the formation of such a novel phase of matter in the absence of external magnetic field.
基金support from the Ministry of Science and Technology of Chinathe National Natural Science Foundation of China and Chinese Academy of Sciences
文摘Recently,the discovery of vanadium-based kagome metal AV_(3)Sb_(5)(A=K,Rb,Cs)has attracted great interest in the field of superconductivity due to the coexistence of superconductivity,non-trivial surface state and multiple density waves.In this topical review,we present recent works of superconductivity and unconventional density waves in vanadium-based kagome materials AV_(3)Sb_(5).We start with the unconventional charge density waves,which are thought to correlate to the time-reversal symmetry-breaking orders and the unconventional anomalous Hall effects in AV_(3)Sb_(5).Then we discuss the superconductivity and the topological band structure.Next,we review the competition between the superconductivity and charge density waves under different conditions of pressure,chemical doping,thickness,and strains.Finally,the experimental evidence of pseudogap pair density wave is discussed.
基金supported by the National Natural Science Foundation of China(Grant Nos.12234016 and 12174317)supported by the National Natural Science Foundation of China(Grant No.12074031)+1 种基金supported by the National Natural Science Foundation of China(Grant No.12304180)supported by the New Cornerstone Science Foundation。
文摘The superconducting state typically favors a uniform spatial distribution akin to ferromagnetism.Nevertheless,the pair-densitywave state exhibits sign changes in the pairing order,leading to potential frustrations in phase coherence.We propose a mechanism to the sextetting order stemming from the frustrations in the phase coherence of a pair-density-wave state,whose spatial modulation manifests a vortex-antivortex honeycomb lattice.The classical ground state configurations are mapped to Baxter's three-coloring model,revealing a macroscopic degeneracy accompanied by extensive entropy.The phase coherence problem intertwines the U(1)phases and the vorticity variables.While the resultant color and phase fluctuations suppress the pair-densitywave order,they maintain the sextetting order above the superconducting transition temperature(T_(c)).The 1/3-fractional vortex emerges as the fundamental topological defect in the sextetting order.This novel mechanism of frustrated superconductivity provides an alternative explanation for the experimental observed fractional oscillations in CsV_(3)Sb_(5).
