Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of ...Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses,making this technique advantageous over macroscopic approaches.Despite its widespread application in ferroelectrics,it has rarely been used to investigate the ferrielectric(FiE)behaviors in antiferroelectric(AFE)materials.Herein,the PFM was utilized to study the local electromechanical behavior and distribution of FiE,and the AFE phases of PbZrO_(3)thin-film were studied,where only the FiE behavior is observable using a macroscopic approach.The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages.In contrast,the AFE region only yields an observable response at high voltages.Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations.Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior,thereby providing insights to guide property modification and potential applications.展开更多
The RMn_(2)O_(5) manganite compounds represent one class of multiferroic family with magnetic origins,which has been receiving continuous attention in the past decade.So far,our understanding of the magnetic origins f...The RMn_(2)O_(5) manganite compounds represent one class of multiferroic family with magnetic origins,which has been receiving continuous attention in the past decade.So far,our understanding of the magnetic origins for ferroelectricity in RMn_(2)O_(5) is associated with the nearly collinear antiferromagnetic structure of Mn ions,while the exchange striction induced ionic displacements are the consequence of the spin frustration competitions.While this scenario may be applied to almost all RMn_(2)O_(5) members,its limitation is either clear:the temperature-dependent behaviors of electric polarization and its responses to external stimuli are seriously materials dependent.These inconsistences raise substantial concern with the state-of-the-art physics of ferroelectricity in RMn_(2)O_(5).In this mini-review,we present our recent experimental results on the roles of the 4f moments from R ions which are intimately coupled with the 3d moments from Mn ions.DyMn_(2)O_(5) is a golden figure for illustrating these roles.It is demonstrated that the spin structure accommodates two nearly collinear sublattices which generate respectively two ferroelectric(FE)sublattices,enabling DyMn_(2)O_(5) an emergent ferrielectric(FIE)system rarely identified in magnetically induced FEs.The evidence is presented from several aspects,including FIE-like phenomena and magnetoelectric responses,proposed structural model,and experimental check by nonmagnetic substitutions of the 3d and 4f moments.Additional perspectives regarding possible challenges in understanding the multiferroicity of RMn_(2)O_(5) as a generalized scenario are discussed.展开更多
Size-driven transition of an antiferroelectric into a polar ferroelectric or ferrielectric state is a strongly debated issue from both experimental and theoretical perspectives.While critical thickness limits for such...Size-driven transition of an antiferroelectric into a polar ferroelectric or ferrielectric state is a strongly debated issue from both experimental and theoretical perspectives.While critical thickness limits for such transitions have been explored,a bottom-up approach in the ultrathin limit considering few atomic layers could provide insight into the mechanism of stabilization of the polar phases over the antipolar phase seen in bulk PbZrO_(3).Here,we use first-principles density functional theory to predict the stability of polar phases in Pt/PbZrO_(3)/Pt nanocapacitors.In a few atomic layer thick slabs of PbZrO_(3) sandwiched between Pt electrodes,we find that the polar phase originating from the well established R3c phase of bulk PbZrO_(3) is energetically favorable over the antipolar phase originating from the Pbam phase of bulk PbZrO_(3).The famous triple-well potential of antiferroelectric PbZrO_(3) is modified in the nanocapacitor limit in such a way as to swap the positions of the global and local minima,stabilizing the polar phase relative to the antipolar one.The size effect is decomposed into the contributions from dimensionality reduction,surface charge screening,and interfacial relaxation,which reveals that it is the creation of well-compensated interfaces that stabilizes the polar phases over the antipolar ones in nanoscale PbZrO_(3).展开更多
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIP)(No.2019R1I1A1A01063888)the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2019R1A6A1A03033215)F.P.Z.acknowledges the Alexander von Humboldt Foundation(AvH)for the fellowship with award number 1203828,and Z.L.acknowledges the LOEWE program of the State of Hesse,Germany,within the project FLAME(Fermi Level Engineering of Antiferroelectric Materials for Energy Storage and Insulation Systems).
文摘Piezoresponse force microscopy(PFM)is an indispensable tool in the investigation of local electromechanical responses and polarization switching.The acquired data provide spatial information on the local disparity of polarization switching and electromechanical responses,making this technique advantageous over macroscopic approaches.Despite its widespread application in ferroelectrics,it has rarely been used to investigate the ferrielectric(FiE)behaviors in antiferroelectric(AFE)materials.Herein,the PFM was utilized to study the local electromechanical behavior and distribution of FiE,and the AFE phases of PbZrO_(3)thin-film were studied,where only the FiE behavior is observable using a macroscopic approach.The FiE region resembles a ferroelectric material at low voltages but exhibits a unique on-field amplitude response at high voltages.In contrast,the AFE region only yields an observable response at high voltages.Phase-field simulations reveal the coexistence of AFE and FiE states as well as the phase-transition processes that underpin our experimental observations.Our work illustrates the usefulness of PFM as an analytical tool to characterize AFE/FiE materials and their phase-coexistence behavior,thereby providing insights to guide property modification and potential applications.
基金supported by the Natural Science Foundation of China(Grant Nos.11234005 and 51431006)the National 973 Projects of China(Grant No.2011CB922101).
文摘The RMn_(2)O_(5) manganite compounds represent one class of multiferroic family with magnetic origins,which has been receiving continuous attention in the past decade.So far,our understanding of the magnetic origins for ferroelectricity in RMn_(2)O_(5) is associated with the nearly collinear antiferromagnetic structure of Mn ions,while the exchange striction induced ionic displacements are the consequence of the spin frustration competitions.While this scenario may be applied to almost all RMn_(2)O_(5) members,its limitation is either clear:the temperature-dependent behaviors of electric polarization and its responses to external stimuli are seriously materials dependent.These inconsistences raise substantial concern with the state-of-the-art physics of ferroelectricity in RMn_(2)O_(5).In this mini-review,we present our recent experimental results on the roles of the 4f moments from R ions which are intimately coupled with the 3d moments from Mn ions.DyMn_(2)O_(5) is a golden figure for illustrating these roles.It is demonstrated that the spin structure accommodates two nearly collinear sublattices which generate respectively two ferroelectric(FE)sublattices,enabling DyMn_(2)O_(5) an emergent ferrielectric(FIE)system rarely identified in magnetically induced FEs.The evidence is presented from several aspects,including FIE-like phenomena and magnetoelectric responses,proposed structural model,and experimental check by nonmagnetic substitutions of the 3d and 4f moments.Additional perspectives regarding possible challenges in understanding the multiferroicity of RMn_(2)O_(5) as a generalized scenario are discussed.
基金support by the U.S.National Science Foundation under grant No.DMR-2219476I.P.acknowledges financial support by the U.S.Department of Energy,Office of Basic Energy Sciences,Division of Materials Sciences and Engineering under grant DE-SC0005245+3 种基金Computational support was provided by the National Energy Research Scientific Computing Center(NERSC)a U.S.Department of Energy,Office of Science User Facility located at Lawrence Berkeley National Laboratory,operated under Contract No.DE-AC02-05CH11231 using NERSC award BES-ERCAP-0025236L.J.acknowledges support from SFI grant SFI/21/US/3785A.K.gratefully acknowledges support from Department of Education and Learning NI through grant USI-211.
文摘Size-driven transition of an antiferroelectric into a polar ferroelectric or ferrielectric state is a strongly debated issue from both experimental and theoretical perspectives.While critical thickness limits for such transitions have been explored,a bottom-up approach in the ultrathin limit considering few atomic layers could provide insight into the mechanism of stabilization of the polar phases over the antipolar phase seen in bulk PbZrO_(3).Here,we use first-principles density functional theory to predict the stability of polar phases in Pt/PbZrO_(3)/Pt nanocapacitors.In a few atomic layer thick slabs of PbZrO_(3) sandwiched between Pt electrodes,we find that the polar phase originating from the well established R3c phase of bulk PbZrO_(3) is energetically favorable over the antipolar phase originating from the Pbam phase of bulk PbZrO_(3).The famous triple-well potential of antiferroelectric PbZrO_(3) is modified in the nanocapacitor limit in such a way as to swap the positions of the global and local minima,stabilizing the polar phase relative to the antipolar one.The size effect is decomposed into the contributions from dimensionality reduction,surface charge screening,and interfacial relaxation,which reveals that it is the creation of well-compensated interfaces that stabilizes the polar phases over the antipolar ones in nanoscale PbZrO_(3).
