One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static o...One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static order.However,there is no consensus on the existence of a QSL state in any real material so far,due to inevitable disorder and intricate competing exchange interactions on frustrated spin lattices.Here we report systematic heat transport measurements on a honeycomb-lattice compound BaCo_(2)(AsO_(4))_(2),which manifests magnetic order in zero field.In a narrow in-plane field range after the magnetic order is nearly suppressed,in both perpendicular and parallel to the zigzag direction,a finite residual linear term of thermal conductivity is clearly observed,which is attributed to mobile fermionic excitations.In addition,the spin-phonon scattering rate exhibits a T-linear behavior when the order disappears.These observations suggest a partial QSL state with gapless spinon excitations in BaCo_(2)(AsO_(4))_(2),that emerges when a portion of the spins remains ordered,and vanishes as the spins become progressively polarized.展开更多
Dialogues are fundamentally driven by xu(C. Wang, 2016, 2017), a Chinese word meaning continuation that captures the process in which interlocutors participate in interaction through the actions of(utterance) completi...Dialogues are fundamentally driven by xu(C. Wang, 2016, 2017), a Chinese word meaning continuation that captures the process in which interlocutors participate in interaction through the actions of(utterance) completion,(content) extension, and(topic) creation(CEC). This article reports a conversation analytic case study designed to investigate how the continuation strategies of CEC are used in real-time communication to achieve mutual understanding, and thus to construct intersubjectivity(Verhagen, 2005) and promote the development of second language(L2)interactional competence. Our data consisted of audio and video recordings of a 25-minute conversation between two L2 English speakers, one expert and one novice, and a stimulated recall interview with them. Results revealed that the expert employed CEC at the early stage of interaction to maintain successful communication, and the novice gradually aligned with the expert and used CEC to achieve mutual understanding, construct intersubjectivity, and create opportunities for interaction and learning at the late stage, displaying her development of L2 interactional competence. Our findings have useful implications for theoretical and methodological development of the xu-argument studies as well as for xu-based L2 pedagogy.展开更多
When a ferromagnet(FM)couples to a spin glass(SG),the hidden nature of SG may imprint on the FM via their interfacial coupling,probably resulting in elongated magnetic relaxation and enhanced unidirectional and uniaxi...When a ferromagnet(FM)couples to a spin glass(SG),the hidden nature of SG may imprint on the FM via their interfacial coupling,probably resulting in elongated magnetic relaxation and enhanced unidirectional and uniaxial anisotropies.In parallel with the study of interfacial roles,e.g.interfacial coupling and matching,we focused on the influence of the competing interactions in SG(JSG)on the magnetic relaxation properties of SG/FM bilayer and the FM magnetization reversal involving exchange bias field(HE)and coercivity(HC).A fastest decay of relaxation in SG/FM bilayer is found at an intermediate JSG^5.2 erg/cm2 and the relaxation parameters related to JSG are nonmonotonic.On the other hand,a pronounced HE of^0.26 kOe is observed at small JSG,and as JSG increases larger than 2.275 erg/cm2,HE decreases by an order of magnitude and levels off,i.e.,a net EB remains.He is sensitive to JSG only at JSG above 2.275 erg/cm2 and exhibits a minimum value at JSG=4.55 erg/cm2,just below 5.2 erg/cm2 where the relaxation decay is the fastest.Microscopic analysis unravels that the net magnetization associated with unidirectional magnetic stabilization and the large-area FM-like domains in SG are favored at small JSG,while with increasing JSG,the SG spins spontaneously reverse and thus the energy barriers are smeared out.A high susceptibility and a strong interfacial coupling lead to FM magnetization reversal under weaker fields and thus a decrease in coercivity.For too large JSG(exceeding 5.2 erg/cm2),magnetic frustration extends over the domains in SG meanwhile fierce energy competition occurs frequently,resembling enhanced quantum fluctuations.As a result,dynamic relaxation and statistic coercivity are both recovered.This work tells us that the independent modulations of unidirectional and uniaxial anisotropies are possible in SG-based systems through precisely controlling JSG,which is desired for application in the read/write head in future data storage media.展开更多
Multicomponent superconductors exhibit nontrivial vortex behaviors due to the various vortex–vortex interactions,including the competing one in the recently proposed type-1.5 superconductor.However,potential candidat...Multicomponent superconductors exhibit nontrivial vortex behaviors due to the various vortex–vortex interactions,including the competing one in the recently proposed type-1.5 superconductor.However,potential candidate that can be used to study the multicomponent superconductivity is rare.Here,we prepared an artificial superconducting multilayer to act as an alternative approach to study multicomponent superconductivity.The additional repulsive length and the coupling strength among superconducting films were regulated by changing the thickness of the insulting layer.The magnetization measurements were performed to clarify the effect of the competition between the repulsive vortex interactions on the macroscopic superconductivity.The vortex phase diagram and the optimum critical current density have been determined.Furthermore,a second magnetization effect is observed,and is attributed to the upper layer,which provides the weak pinning sites to localize the flux lines.The pinning behaviors switches to the mixed type with the increase of the insulting layer thicknesses.Our results open a new perspective to the study and related applications of the multilayer superconducting systems.展开更多
Shaping learner contributions(SLC)in teacher's verbal feedback as an essential aspect of classroom interactional com-petence(CIC)to encourage modified language output and negotiation for meaning has been considere...Shaping learner contributions(SLC)in teacher's verbal feedback as an essential aspect of classroom interactional com-petence(CIC)to encourage modified language output and negotiation for meaning has been considered as facilitative for SLA,yet less recognized.This study explores classroom discourse to understand teacher's talk in SLC from two Chinese EFL classrooms,aiming to provide suggestions for EFL classrooms to enhancelearning.By integrating the results fromclose analysis and IDLab,16 SLC feedback strategies have been elicited,such as scaffolding,extending wait-time,code-switching,etc.,most of which are con-sistent with previous studies except for a new discovery,termed as emphasizing knowledge,but it reveals thatthey are not always constructive with respect to CIC.Thus,this study contributes a significant role in helping teachers and teacher education adopt ef-fective teaching practices and in introducing the new thought of CIC into the Chinese EFL context.展开更多
基金funded by the National Natural Science Foundations of China(Grant Nos.12034004 and 12174064)the Shanghai Municipal Science and Technology Major Project(Grant No.2019SHZDZX01)+2 种基金the Innovation Program for Quantum Science and Technology(Grant No.2024ZD0300104)supported by U.S.DOE BES DE-SC0012311the Robert A.Welch Foundation under Grant No.C-1839,respectively(P.D.)。
文摘One important issue in current condensed matter physics is the search of quantum spin liquid(QSL),an exotic magnetic state with strongly-fluctuating and highly-entangled spins down to zero temperature without static order.However,there is no consensus on the existence of a QSL state in any real material so far,due to inevitable disorder and intricate competing exchange interactions on frustrated spin lattices.Here we report systematic heat transport measurements on a honeycomb-lattice compound BaCo_(2)(AsO_(4))_(2),which manifests magnetic order in zero field.In a narrow in-plane field range after the magnetic order is nearly suppressed,in both perpendicular and parallel to the zigzag direction,a finite residual linear term of thermal conductivity is clearly observed,which is attributed to mobile fermionic excitations.In addition,the spin-phonon scattering rate exhibits a T-linear behavior when the order disappears.These observations suggest a partial QSL state with gapless spinon excitations in BaCo_(2)(AsO_(4))_(2),that emerges when a portion of the spins remains ordered,and vanishes as the spins become progressively polarized.
文摘Dialogues are fundamentally driven by xu(C. Wang, 2016, 2017), a Chinese word meaning continuation that captures the process in which interlocutors participate in interaction through the actions of(utterance) completion,(content) extension, and(topic) creation(CEC). This article reports a conversation analytic case study designed to investigate how the continuation strategies of CEC are used in real-time communication to achieve mutual understanding, and thus to construct intersubjectivity(Verhagen, 2005) and promote the development of second language(L2)interactional competence. Our data consisted of audio and video recordings of a 25-minute conversation between two L2 English speakers, one expert and one novice, and a stimulated recall interview with them. Results revealed that the expert employed CEC at the early stage of interaction to maintain successful communication, and the novice gradually aligned with the expert and used CEC to achieve mutual understanding, construct intersubjectivity, and create opportunities for interaction and learning at the late stage, displaying her development of L2 interactional competence. Our findings have useful implications for theoretical and methodological development of the xu-argument studies as well as for xu-based L2 pedagogy.
基金financially supported by the National Natural Science Foundation of China(No.11774045)the Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(No.20180510008)the Fundamental Research Funds for Central Universities(Nos.N182410008-1 and N180506001)。
文摘When a ferromagnet(FM)couples to a spin glass(SG),the hidden nature of SG may imprint on the FM via their interfacial coupling,probably resulting in elongated magnetic relaxation and enhanced unidirectional and uniaxial anisotropies.In parallel with the study of interfacial roles,e.g.interfacial coupling and matching,we focused on the influence of the competing interactions in SG(JSG)on the magnetic relaxation properties of SG/FM bilayer and the FM magnetization reversal involving exchange bias field(HE)and coercivity(HC).A fastest decay of relaxation in SG/FM bilayer is found at an intermediate JSG^5.2 erg/cm2 and the relaxation parameters related to JSG are nonmonotonic.On the other hand,a pronounced HE of^0.26 kOe is observed at small JSG,and as JSG increases larger than 2.275 erg/cm2,HE decreases by an order of magnitude and levels off,i.e.,a net EB remains.He is sensitive to JSG only at JSG above 2.275 erg/cm2 and exhibits a minimum value at JSG=4.55 erg/cm2,just below 5.2 erg/cm2 where the relaxation decay is the fastest.Microscopic analysis unravels that the net magnetization associated with unidirectional magnetic stabilization and the large-area FM-like domains in SG are favored at small JSG,while with increasing JSG,the SG spins spontaneously reverse and thus the energy barriers are smeared out.A high susceptibility and a strong interfacial coupling lead to FM magnetization reversal under weaker fields and thus a decrease in coercivity.For too large JSG(exceeding 5.2 erg/cm2),magnetic frustration extends over the domains in SG meanwhile fierce energy competition occurs frequently,resembling enhanced quantum fluctuations.As a result,dynamic relaxation and statistic coercivity are both recovered.This work tells us that the independent modulations of unidirectional and uniaxial anisotropies are possible in SG-based systems through precisely controlling JSG,which is desired for application in the read/write head in future data storage media.
基金Project supported by the National Natural Science Foundation of China (Grant No. 12174242)the National Key Research and Development Program of China (Grant No. 2018YFA0704300)+1 种基金the Key Research Project of Zhejiang Laboratory (Grant No. 2021PE0AC02)the support by the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning
文摘Multicomponent superconductors exhibit nontrivial vortex behaviors due to the various vortex–vortex interactions,including the competing one in the recently proposed type-1.5 superconductor.However,potential candidate that can be used to study the multicomponent superconductivity is rare.Here,we prepared an artificial superconducting multilayer to act as an alternative approach to study multicomponent superconductivity.The additional repulsive length and the coupling strength among superconducting films were regulated by changing the thickness of the insulting layer.The magnetization measurements were performed to clarify the effect of the competition between the repulsive vortex interactions on the macroscopic superconductivity.The vortex phase diagram and the optimum critical current density have been determined.Furthermore,a second magnetization effect is observed,and is attributed to the upper layer,which provides the weak pinning sites to localize the flux lines.The pinning behaviors switches to the mixed type with the increase of the insulting layer thicknesses.Our results open a new perspective to the study and related applications of the multilayer superconducting systems.
文摘Shaping learner contributions(SLC)in teacher's verbal feedback as an essential aspect of classroom interactional com-petence(CIC)to encourage modified language output and negotiation for meaning has been considered as facilitative for SLA,yet less recognized.This study explores classroom discourse to understand teacher's talk in SLC from two Chinese EFL classrooms,aiming to provide suggestions for EFL classrooms to enhancelearning.By integrating the results fromclose analysis and IDLab,16 SLC feedback strategies have been elicited,such as scaffolding,extending wait-time,code-switching,etc.,most of which are con-sistent with previous studies except for a new discovery,termed as emphasizing knowledge,but it reveals thatthey are not always constructive with respect to CIC.Thus,this study contributes a significant role in helping teachers and teacher education adopt ef-fective teaching practices and in introducing the new thought of CIC into the Chinese EFL context.
