Transition metal fluorides(TMFs)cathode materials have shown extraordinary promises for electrochemical energy storage,but the understanding of their electrochemical reaction mechanisms is still a matter of debate due...Transition metal fluorides(TMFs)cathode materials have shown extraordinary promises for electrochemical energy storage,but the understanding of their electrochemical reaction mechanisms is still a matter of debate due to the complicated and continuous changing in the battery internal environment.Here,we design a novel iron fluoride(FeF_(2))aggregate assembled with cylindrical nanoparticles as cathode material to build FeF_(2) lithium-ion batteries(LIBs)and employ advanced in situ magnetometry to detect their intrinsic electronic structure during cycling in real time.The results show that FeF_(2) cannot be involved in complete conversion reactions when the FeF_(2) LIBs operate between the conventional voltage range of 1.0–4.0 V,and that the corresponding conversion ratio of FeF_(2) can be further estimated.Importantly,we first demonstrate that the spin-polarized surface capacitance exists in the FeF_(2) cathode by monitoring the magnetic responses over various voltage ranges.The research presents an original and insightful method to examine the conversion mechanism of TMFs and significantly provides an important reference for the future artificial design of energy systems based on spinpolarized surface capacitance.展开更多
Owing to the potential ability of metal nanoparticles to enhance the performance of energy storage devices,their catalytic performance has been studied by many researchers.However,a limited number of suitable characte...Owing to the potential ability of metal nanoparticles to enhance the performance of energy storage devices,their catalytic performance has been studied by many researchers.However,a limited number of suitable characterization techniques does not allow fully elucidating their catalytic mechanism.Herein,high‐accuracy operando magnetometry is employed to investigate the catalytic properties of a cobalt oxide electrode for lithium‐ion batteries fabricated by magnetron sputtering.Using this technique,the magnetic responses generated by the Co‐catalyzed reversible formation and decomposition of a polymer/gel‐like film are successfully detected.A series of CoO/Co films are prepared by magnetron sputtering in different environments at various sputtering times to study the influence of Co content and film thickness on their catalytic properties.It is clearly demonstrated that increasing the Co content enhances the magnetic signal associated with the catalysis process.Furthermore,decreasing the electrode thickness increases the area affected by the catalytic reactions,which in turn enhances the corresponding magnetic responses.The obtained results experimentally confirm the catalytic activity of Co metal nanoparticles and provide a scientific guidance for designing advanced energy storage devices.This work also shows that operando magnetometry is a versatile technique for studying the catalytic effects of transition metals.展开更多
We investigated the hyperthermal and magnetic properties of the stable magnetic suspension of magnetite nanoparticles. With this purpose in mind, we designed a low-frequency oscillator, 300 W, 300 KHz. A sample of the...We investigated the hyperthermal and magnetic properties of the stable magnetic suspension of magnetite nanoparticles. With this purpose in mind, we designed a low-frequency oscillator, 300 W, 300 KHz. A sample of the magnetic suspension was placed in the induction coil and heated up to 55°C for 30 minutes. Based on the results of measurements of transverse susceptibility, we can infer that the suspension was superparamagnetic at room temperature and transformed into the magnetic state at nitrogen temperature. Comparing the obtained experimental results with the literature data, we assessed the mean size of nanoparticles, which made up about 10 nm. Computer simulation assessment on the basis of magnetization curve gives close results.展开更多
The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with ...The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.展开更多
This present study was aimed to investigate the localizable diagnostic value of magnetoencephalography （MEG） combined with synthetic aperture magnetometry （SAM） in childhood absence epilepsy （CAE）. Thirteen CAE ...This present study was aimed to investigate the localizable diagnostic value of magnetoencephalography （MEG） combined with synthetic aperture magnetometry （SAM） in childhood absence epilepsy （CAE）. Thirteen CAE patients underwent MEG detection at resting state and after hyperventilation, and then the epileptic loci were located by SAM. In the thirteen CAE patients, epileptic foci were found in five cases （38.5%）, and they were all located in the bilateral frontal lobe, suggesting that the frontal lobe in some CAE patients may serve as the epileptic foci. Our findings indicate that MEG combined with SAM could be of diagnostic value in localizing the epileptic foci in certain CAE patients.展开更多
A new microcavity magnetometry with FeGaB thin film achieves 1.68 pT/Hz/2 sensitivity,which is two orders of magnitude improvement over previous work.Corona current detection has been demonstrated using this magnetome...A new microcavity magnetometry with FeGaB thin film achieves 1.68 pT/Hz/2 sensitivity,which is two orders of magnitude improvement over previous work.Corona current detection has been demonstrated using this magnetometer.展开更多
Interfacial space charge storage between ionic and electronic conductor is a promising scheme to further improve energy and power density of alkali metal ion batteries(AMIBs).However,the general behavior of space char...Interfacial space charge storage between ionic and electronic conductor is a promising scheme to further improve energy and power density of alkali metal ion batteries(AMIBs).However,the general behavior of space charge storage in AMIBs has been less investigated experimentally,mostly due to the complicated electrochemical behavior and lack of proper characterization techniques.Here,we use operando magnetometry to verify that in FeSe_(2)AMIBs,abundant Li^(+)/Na^(+)/K^(+)(M^(+))can be stored at M_(2)Se phase while electrons accumulate at Fe nanoparticles,forming interfacial space charge layers.Magnetic and dynamics tests further demonstrate that with increasing ionic radius from Li^(+),Na^(+)to K^(+),the reaction kinetics can be hindered,resulting in limited Fe formation and reduced space charge storage capacity.This work lays solid foundation for studying the complex interfacial effect in electrochemical processes and designing advanced energy storage devices with substantial capacity and considerable power density.展开更多
Precision measurement of magnetic fields is a crucial issue in both fundamental scientific research and practical sensing technology.The sensitive detection of a vector magnetic field poses a significant challenge in ...Precision measurement of magnetic fields is a crucial issue in both fundamental scientific research and practical sensing technology.The sensitive detection of a vector magnetic field poses a significant challenge in quantum magnetometry,particularly in estimating a vector DC magnetic field with high precision.Here,we propose a comprehensive protocol for quantum vector DC magnetometry,utilizing selective phase accumulation in both non-entangled and entangled quantum probes.Building upon the principles of Ramsey interferometry,our protocol enables the selective accumulation of phase for a specific magnetic field component by incorporating a meticulously designed pulse sequence.In the individual measurement scheme,we employ three individual quantum interferometries to independently estimate each of the three magnetic field components.Alternatively,in the simultaneous measurement scheme,the application of a pulse sequence along different directions enables the simultaneous estimation of all three magnetic field components using only one quantum interferometry.Notably,by employing an entangled state(such as the Greenberger-Horne-Zeilinger state)as the input state,the measurement precisions of all three components may reach the Heisenberg limit.This study not only establishes a general protocol for measuring vector magnetic fields using quantum probes,but also presents a viable pathway for achieving entanglement-enhanced multi-parameter estimation.展开更多
Secondary batteries have significantly promoted the technological advancement of human society.In turn,evolving technology has placed higher performance demands on secondary batteries.An understanding of the relations...Secondary batteries have significantly promoted the technological advancement of human society.In turn,evolving technology has placed higher performance demands on secondary batteries.An understanding of the relationship between the material structure and electrochemical performance of these batteries is important in addressing the limitations of current research.In particular,the relationship between material spin and electrochemical properties has increasingly attracted attention.To obtain important spin information for electrode materials,a power characterization technique is typically needed.Spin properties are closely related to magnetism,and thus,magnetometry can be utilized for characterization.Focusing on magnetometry characterization techniques,this work first discusses the technical principles of magnetometry and then summarizes the research progress of this approach in the study of electrode materials,especially operando magnetometry.A comprehensive analysis reveals that magnetometry can be used to characterize various complex problems in electrochemical processes and has broad applications in energy electrochemistry research.This work facilitates a deeper understanding of the importance of magnetometry characterization techniques in electrode material research and further promotes its development in the energy electrochemistry field.展开更多
This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operat...This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operation and compact integration,restricting the sensitivity and dynamic range of the sensor.The broadband antenna based on a dualfrequency monopole structure achieves a bandwidth extension of 777 MHz at the Zeeman splitting frequency of 2.87 GHz,with the dual resonant points positioned near 2.87 GHz.Additionally,high-resolution imaging of the microwave magnetic field on the antenna surface was performed using a diamond optical fiber probe,which verified the dual-frequency design principle.Experimental results using the proposed antenna demonstrate the outstanding performance of the NV centerbased magnetic sensor:a sensitivity of 55 nT/Hz^(1/2)and a dynamic range of up to 54.0 dB.Compared to sensors using conventional antennas,the performance has been significantly improved.展开更多
We theoretically and experimentally study the optimal duty cycle and pumping rate for square-wave amplitudemodulated Bell–Bloom magnetometers.The theoretical and the experimental results are in good agreement for dut...We theoretically and experimentally study the optimal duty cycle and pumping rate for square-wave amplitudemodulated Bell–Bloom magnetometers.The theoretical and the experimental results are in good agreement for duty cycles and corresponding pumping rates ranging over 2 orders of magnitude.Our study gives the maximum field response as a function of duty cycle and pumping rate.Especially,for a fixed duty cycle,the maximum field response is obtained when the time averaged pumping rate,which is the product of pumping rate and duty cycle,is equal to the transverse relaxation rate in the dark.By using a combination of small duty cycle and large pumping rate,one can increase the maximum field response by up to a factor of 2 or π /2,relative to that of the sinusoidal modulation or the 50% duty cycle square-wave modulation respectively.We further show that the same pumping condition is also practically optimal for the sensitivity due to the fact that the signal at resonance is insensitive to the fluctuations of pumping rate and duty cycle.展开更多
Magnetic surveying is one of the methods of studying shallow subsurface structures by measuring variation in an area which can be compared to the surroundings.This method can disclose the magnetic minerals or metallic...Magnetic surveying is one of the methods of studying shallow subsurface structures by measuring variation in an area which can be compared to the surroundings.This method can disclose the magnetic minerals or metallic objects underground.In addition, fluid flow can affect these magnetic anomalies too. This paper is the result of a case study done in a 2500 m^2 region which investigates and reveals the effect展开更多
Magnetically anisotropic nanoparticle monolayer films are of great interest for the development of ap-plications such as high-density data storage,sensors.However,the formation of large-scale magnetically anisotropic ...Magnetically anisotropic nanoparticle monolayer films are of great interest for the development of ap-plications such as high-density data storage,sensors.However,the formation of large-scale magnetically anisotropic monolayer film is a challenging task.Here,we provide a new way to fabricate large-scale area of Fe_(3)O_(4) nanoparticle monolayer films by vacuum deposition technique(matrix-assisted pulsed laser evaporation,MAPLE).During the deposition process,only interactions between nanoparticles influence nanoparticle self-assembly behaviors.A strong magnetic anisotropy,characterized by in-plane and out-of-plane coercivity and saturation field obtained by DCM(dynamic cantilever magnetometry),was obtained both in cubic and spherical Fe_(3)O_(4) nanoparticle monolayer films.The inter-particle dipolar interaction but not crystal anisotropy is responsible for this effective magnetic anisotropy,which has been proved by Monte-Carlo simulations.展开更多
When the ground state hyperfine splitting of alkali metal vapor atoms is well optically resolved, the spin coherence on one hyperfine sublevel can be generated directly or indirectly by pumping the same or the other s...When the ground state hyperfine splitting of alkali metal vapor atoms is well optically resolved, the spin coherence on one hyperfine sublevel can be generated directly or indirectly by pumping the same or the other sublevel respectively. We experimentally studied the pump power dependence of the field response of a Bell-Bloom magnetometer for the two pumping schemes in a paraffin coated ^87Rb vapor cell. We find that although the maximum field response is achieved by combining the two pumping schemes, indirect pumping alone can do nearly as good while being much simpler to operate. We have achieved a sensitivity of 100 fT/Hz^1/2 with a single indirect pump at room temperature.展开更多
LiFePO4 materials synthesized using FePO4(H2O)2 and Li2CO3 blend were optimized in view of their use as positive electrodes in Li-ion batteries for hybrid electric vehicles. A strict control of the structural properti...LiFePO4 materials synthesized using FePO4(H2O)2 and Li2CO3 blend were optimized in view of their use as positive electrodes in Li-ion batteries for hybrid electric vehicles. A strict control of the structural properties was made by the combination of X-ray diffraction, FT-infrared spectroscopy and magnetometry. The impact of the ferromagnetic clus-ters (γ-Fe2O3 or Fe2P) on the electrochemical response was examined. The electrochemical performances of the opti-mized LiFePO4 powders investigated at 60℃ are excellent in terms of capacity retention (153 mAh·g-1 at 2C) as well as in terms of cycling life. No iron dissolution was observed after 200 charge-discharge cycles at 60℃ for cells containing Li foil, Li4Ti5O12, or graphite as negative electrodes.展开更多
Fe_(3)GaTe_(2)has attracted significant interest due to its intrinsic room-temperature ferromagnetism,yet its magnetic interactions remain debated.We thoroughly investigate the magnetism of Fe_(3)GaTe_(2)using critica...Fe_(3)GaTe_(2)has attracted significant interest due to its intrinsic room-temperature ferromagnetism,yet its magnetic interactions remain debated.We thoroughly investigate the magnetism of Fe_(3)GaTe_(2)using critical analysis,nitrogen–vacancy(NV)center magnetometry,and Density Function Theory(DFT).Our critical phenomenon analysis with exponents[β=0.3706(9),=1.32(6),σ=4.7(2)]and DFT calculations reveal competition between itinerant and localized spins driven by anisotropic coupling,which can be attributed to a net charge transfer of approximately 0.22 electrons from Fe^(3+)to surrounding Ge/Te atoms.As confirmed by NV center magnetometry,the ferromagnetism in Fe_(3)GaTe_(2)remains robust even in thin-layered sheet of 16 nm(corresponding to approximately 20 layers).The out-of-plane ferromagnetism in thin Fe_(3)GaTe_(2)sheets is stabilized due to the distinct spin interaction energies between intralayers(J_(1)~66.74 meV andJ_(2)~17.33 meV)and interlayers(J_(z)~3.78 meV).In addition,the constant energy contour profiles near the Fermi surface of Fe_(3)GaTe_(2)suggest the presence of both hole and electron pockets with a distorted contour around the K/K′point,indicating hexagonal trigonal warping effects.Furthermore,the layer-resolved electronic band structure uncovers a layer–valley coupling near the Fermi surface,with bands at valleys K and K′associated with different layers.These findings pave way for advanced electronic applications operating above-room-temperature.展开更多
Color centers are versatile systems that generate quantum light,sense magnetic fields and produce spin-photon entanglement.We review how these properties have pushed the limits of fundamental knowledge in a variety of...Color centers are versatile systems that generate quantum light,sense magnetic fields and produce spin-photon entanglement.We review how these properties have pushed the limits of fundamental knowledge in a variety of scientific disciplines,from rejecting local-realistic theories to sensing superconducting phase transitions.In the light of recent progress in material processing and device fabrication,we identify new opportunities for interdisciplinary fundamental discoveries in physics and geochemistry.展开更多
The use of magnetic nanoparticles in nanomedicine keeps expanding and,for most applications,the nanoparticles are internalized in cells then left within,bringing the need for accurate,fast,and easy to handle methodolo...The use of magnetic nanoparticles in nanomedicine keeps expanding and,for most applications,the nanoparticles are internalized in cells then left within,bringing the need for accurate,fast,and easy to handle methodologies to assess their behavior in the cellular environment.Herein,a benchtop-size magnetic sensor is introduced to provide real-time precise measurement of nanoparticle magnetism within living cells.The values obtained with the sensor,of cells loaded with different doses of magnetic nanoparticles,are first compared to conventional vibrating sample magnetometry(VSM),and a strong correlation remarkably validates the use of the magnetic sensor as magnetometer to determine the nanoparticle cellular uptake.The sensor is then used to monitor the progressive intracellular degradation of the nanoparticles,over days.Importantly,this real-time in situ measure is performed on a stem cell-spheroid tissue model and can run continuously on a same spheroid,with cells kept alive within.Besides,such continuous magnetic measurement of cell magnetism at the tissue scale does not impact either tissue formation,vibility,or stem cell function,including differentiation and extracellular matrix production.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:51804173。
文摘Transition metal fluorides(TMFs)cathode materials have shown extraordinary promises for electrochemical energy storage,but the understanding of their electrochemical reaction mechanisms is still a matter of debate due to the complicated and continuous changing in the battery internal environment.Here,we design a novel iron fluoride(FeF_(2))aggregate assembled with cylindrical nanoparticles as cathode material to build FeF_(2) lithium-ion batteries(LIBs)and employ advanced in situ magnetometry to detect their intrinsic electronic structure during cycling in real time.The results show that FeF_(2) cannot be involved in complete conversion reactions when the FeF_(2) LIBs operate between the conventional voltage range of 1.0–4.0 V,and that the corresponding conversion ratio of FeF_(2) can be further estimated.Importantly,we first demonstrate that the spin-polarized surface capacitance exists in the FeF_(2) cathode by monitoring the magnetic responses over various voltage ranges.The research presents an original and insightful method to examine the conversion mechanism of TMFs and significantly provides an important reference for the future artificial design of energy systems based on spinpolarized surface capacitance.
文摘Owing to the potential ability of metal nanoparticles to enhance the performance of energy storage devices,their catalytic performance has been studied by many researchers.However,a limited number of suitable characterization techniques does not allow fully elucidating their catalytic mechanism.Herein,high‐accuracy operando magnetometry is employed to investigate the catalytic properties of a cobalt oxide electrode for lithium‐ion batteries fabricated by magnetron sputtering.Using this technique,the magnetic responses generated by the Co‐catalyzed reversible formation and decomposition of a polymer/gel‐like film are successfully detected.A series of CoO/Co films are prepared by magnetron sputtering in different environments at various sputtering times to study the influence of Co content and film thickness on their catalytic properties.It is clearly demonstrated that increasing the Co content enhances the magnetic signal associated with the catalysis process.Furthermore,decreasing the electrode thickness increases the area affected by the catalytic reactions,which in turn enhances the corresponding magnetic responses.The obtained results experimentally confirm the catalytic activity of Co metal nanoparticles and provide a scientific guidance for designing advanced energy storage devices.This work also shows that operando magnetometry is a versatile technique for studying the catalytic effects of transition metals.
文摘We investigated the hyperthermal and magnetic properties of the stable magnetic suspension of magnetite nanoparticles. With this purpose in mind, we designed a low-frequency oscillator, 300 W, 300 KHz. A sample of the magnetic suspension was placed in the induction coil and heated up to 55°C for 30 minutes. Based on the results of measurements of transverse susceptibility, we can infer that the suspension was superparamagnetic at room temperature and transformed into the magnetic state at nitrogen temperature. Comparing the obtained experimental results with the literature data, we assessed the mean size of nanoparticles, which made up about 10 nm. Computer simulation assessment on the basis of magnetization curve gives close results.
基金supported by the National Key R&D Program of China(Grant Nos.2021YFB3202800 and 2023YF0718400)Chinese Academy of Sciences(Grant No.ZDZBGCH2021002)+2 种基金Chinese Academy of Sciences(Grant No.GJJSTD20200001)Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303204)Anhui Initiative in Quantum Information Technologies,USTC Tang Scholar,and the Fundamental Research Funds for the Central Universities.
文摘The application of the vector magnetometry based on nitrogen-vacancy(NV)ensembles has been widely investigatedin multiple areas.It has the superiority of high sensitivity and high stability in ambient conditions with microscale spatialresolution.However,a bias magnetic field is necessary to fully separate the resonance lines of optically detected magneticresonance(ODMR)spectrum of NV ensembles.This brings disturbances in samples being detected and limits the rangeof application.Here,we demonstrate a method of vector magnetometry in zero bias magnetic field using NV ensembles.By utilizing the anisotropy property of fluorescence excited from NV centers,we analyzed the ODMR spectrum of NVensembles under various polarized angles of excitation laser in zero bias magnetic field with a quantitative numerical modeland reconstructed the magnetic field vector.The minimum magnetic field modulus that can be resolved accurately is downto~0.64 G theoretically depending on the ODMR spectral line width(1.8 MHz),and~2 G experimentally due to noisesin fluorescence signals and errors in calibration.By using 13C purified and low nitrogen concentration diamond combinedwith improving calibration of unknown parameters,the ODMR spectral line width can be further decreased below 0.5 MHz,corresponding to~0.18 G minimum resolvable magnetic field modulus.
基金supported by Nanjing Medical Technology Development Grant (No. ZKM05033)
文摘This present study was aimed to investigate the localizable diagnostic value of magnetoencephalography （MEG） combined with synthetic aperture magnetometry （SAM） in childhood absence epilepsy （CAE）. Thirteen CAE patients underwent MEG detection at resting state and after hyperventilation, and then the epileptic loci were located by SAM. In the thirteen CAE patients, epileptic foci were found in five cases （38.5%）, and they were all located in the bilateral frontal lobe, suggesting that the frontal lobe in some CAE patients may serve as the epileptic foci. Our findings indicate that MEG combined with SAM could be of diagnostic value in localizing the epileptic foci in certain CAE patients.
文摘A new microcavity magnetometry with FeGaB thin film achieves 1.68 pT/Hz/2 sensitivity,which is two orders of magnitude improvement over previous work.Corona current detection has been demonstrated using this magnetometer.
基金supported by the National Natural Science Foundation of China(22179066,51804173,and 11674186)the National Science Foundation of Shandong Province(ZR2020MA073)+2 种基金the Science and Technology Board of Qingdao(16-5-1-2jch)Natural Sciences and Engineering Research Council of Canada(NSERC)Discovery grant RGPIN-04178the Canada First Research Excellence Fund。
文摘Interfacial space charge storage between ionic and electronic conductor is a promising scheme to further improve energy and power density of alkali metal ion batteries(AMIBs).However,the general behavior of space charge storage in AMIBs has been less investigated experimentally,mostly due to the complicated electrochemical behavior and lack of proper characterization techniques.Here,we use operando magnetometry to verify that in FeSe_(2)AMIBs,abundant Li^(+)/Na^(+)/K^(+)(M^(+))can be stored at M_(2)Se phase while electrons accumulate at Fe nanoparticles,forming interfacial space charge layers.Magnetic and dynamics tests further demonstrate that with increasing ionic radius from Li^(+),Na^(+)to K^(+),the reaction kinetics can be hindered,resulting in limited Fe formation and reduced space charge storage capacity.This work lays solid foundation for studying the complex interfacial effect in electrochemical processes and designing advanced energy storage devices with substantial capacity and considerable power density.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1404104)the National Natural Science Foundation of China(Grant Nos.12025509,and 12305022)the Key-Area Research and Development Program of Guangdong Province(Grant No.2019B030330001)。
文摘Precision measurement of magnetic fields is a crucial issue in both fundamental scientific research and practical sensing technology.The sensitive detection of a vector magnetic field poses a significant challenge in quantum magnetometry,particularly in estimating a vector DC magnetic field with high precision.Here,we propose a comprehensive protocol for quantum vector DC magnetometry,utilizing selective phase accumulation in both non-entangled and entangled quantum probes.Building upon the principles of Ramsey interferometry,our protocol enables the selective accumulation of phase for a specific magnetic field component by incorporating a meticulously designed pulse sequence.In the individual measurement scheme,we employ three individual quantum interferometries to independently estimate each of the three magnetic field components.Alternatively,in the simultaneous measurement scheme,the application of a pulse sequence along different directions enables the simultaneous estimation of all three magnetic field components using only one quantum interferometry.Notably,by employing an entangled state(such as the Greenberger-Horne-Zeilinger state)as the input state,the measurement precisions of all three components may reach the Heisenberg limit.This study not only establishes a general protocol for measuring vector magnetic fields using quantum probes,but also presents a viable pathway for achieving entanglement-enhanced multi-parameter estimation.
基金the National Natural Science Foundation of China(grant no.22179066)the National Science Foundation of Shandong Province(grant no.ZR2020MA073).
文摘Secondary batteries have significantly promoted the technological advancement of human society.In turn,evolving technology has placed higher performance demands on secondary batteries.An understanding of the relationship between the material structure and electrochemical performance of these batteries is important in addressing the limitations of current research.In particular,the relationship between material spin and electrochemical properties has increasingly attracted attention.To obtain important spin information for electrode materials,a power characterization technique is typically needed.Spin properties are closely related to magnetism,and thus,magnetometry can be utilized for characterization.Focusing on magnetometry characterization techniques,this work first discusses the technical principles of magnetometry and then summarizes the research progress of this approach in the study of electrode materials,especially operando magnetometry.A comprehensive analysis reveals that magnetometry can be used to characterize various complex problems in electrochemical processes and has broad applications in energy electrochemistry research.This work facilitates a deeper understanding of the importance of magnetometry characterization techniques in electrode material research and further promotes its development in the energy electrochemistry field.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFB2012600)the Science and Technology Plan Project of the State Administration of Market Regulation,China(Grant No.2021MK039)the Suqian Talent Elite Program(Grant No.SQQN202414)。
文摘This paper presents a compact broadband antenna that overcomes bandwidth limitations in a diamond nitrogenvacancy(NV)center-based quantum magnetic sensor.Conventional antennas struggle to achieve both broadband operation and compact integration,restricting the sensitivity and dynamic range of the sensor.The broadband antenna based on a dualfrequency monopole structure achieves a bandwidth extension of 777 MHz at the Zeeman splitting frequency of 2.87 GHz,with the dual resonant points positioned near 2.87 GHz.Additionally,high-resolution imaging of the microwave magnetic field on the antenna surface was performed using a diamond optical fiber probe,which verified the dual-frequency design principle.Experimental results using the proposed antenna demonstrate the outstanding performance of the NV centerbased magnetic sensor:a sensitivity of 55 nT/Hz^(1/2)and a dynamic range of up to 54.0 dB.Compared to sensors using conventional antennas,the performance has been significantly improved.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074050)
文摘We theoretically and experimentally study the optimal duty cycle and pumping rate for square-wave amplitudemodulated Bell–Bloom magnetometers.The theoretical and the experimental results are in good agreement for duty cycles and corresponding pumping rates ranging over 2 orders of magnitude.Our study gives the maximum field response as a function of duty cycle and pumping rate.Especially,for a fixed duty cycle,the maximum field response is obtained when the time averaged pumping rate,which is the product of pumping rate and duty cycle,is equal to the transverse relaxation rate in the dark.By using a combination of small duty cycle and large pumping rate,one can increase the maximum field response by up to a factor of 2 or π /2,relative to that of the sinusoidal modulation or the 50% duty cycle square-wave modulation respectively.We further show that the same pumping condition is also practically optimal for the sensitivity due to the fact that the signal at resonance is insensitive to the fluctuations of pumping rate and duty cycle.
文摘Magnetic surveying is one of the methods of studying shallow subsurface structures by measuring variation in an area which can be compared to the surroundings.This method can disclose the magnetic minerals or metallic objects underground.In addition, fluid flow can affect these magnetic anomalies too. This paper is the result of a case study done in a 2500 m^2 region which investigates and reveals the effect
基金financially supported by the National Natural Science Foundation of China (Nos.51771219,51771220 and 52171184)the Zhejiang Provincial Natural Science Foundation of China (No.LD19E010001)+2 种基金the Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science (No.20180510008)the National Key Research and Development Program of China (No.2017YFA0303201)the Major Program of Development Foundation of Hefei Center for Physical Science and Technology (No.2017FXZY003)。
文摘Magnetically anisotropic nanoparticle monolayer films are of great interest for the development of ap-plications such as high-density data storage,sensors.However,the formation of large-scale magnetically anisotropic monolayer film is a challenging task.Here,we provide a new way to fabricate large-scale area of Fe_(3)O_(4) nanoparticle monolayer films by vacuum deposition technique(matrix-assisted pulsed laser evaporation,MAPLE).During the deposition process,only interactions between nanoparticles influence nanoparticle self-assembly behaviors.A strong magnetic anisotropy,characterized by in-plane and out-of-plane coercivity and saturation field obtained by DCM(dynamic cantilever magnetometry),was obtained both in cubic and spherical Fe_(3)O_(4) nanoparticle monolayer films.The inter-particle dipolar interaction but not crystal anisotropy is responsible for this effective magnetic anisotropy,which has been proved by Monte-Carlo simulations.
基金supported by the Natural Science Foundation of Shanghai(Grant No.16ZR1402700)the National Natural Science Foundation of China(Grant No.91636102)the National Key Research and Development Program of China(Grant No.2016YFA0302000)
文摘When the ground state hyperfine splitting of alkali metal vapor atoms is well optically resolved, the spin coherence on one hyperfine sublevel can be generated directly or indirectly by pumping the same or the other sublevel respectively. We experimentally studied the pump power dependence of the field response of a Bell-Bloom magnetometer for the two pumping schemes in a paraffin coated ^87Rb vapor cell. We find that although the maximum field response is achieved by combining the two pumping schemes, indirect pumping alone can do nearly as good while being much simpler to operate. We have achieved a sensitivity of 100 fT/Hz^1/2 with a single indirect pump at room temperature.
文摘LiFePO4 materials synthesized using FePO4(H2O)2 and Li2CO3 blend were optimized in view of their use as positive electrodes in Li-ion batteries for hybrid electric vehicles. A strict control of the structural properties was made by the combination of X-ray diffraction, FT-infrared spectroscopy and magnetometry. The impact of the ferromagnetic clus-ters (γ-Fe2O3 or Fe2P) on the electrochemical response was examined. The electrochemical performances of the opti-mized LiFePO4 powders investigated at 60℃ are excellent in terms of capacity retention (153 mAh·g-1 at 2C) as well as in terms of cycling life. No iron dissolution was observed after 200 charge-discharge cycles at 60℃ for cells containing Li foil, Li4Ti5O12, or graphite as negative electrodes.
基金supported by the National Key R&D Program of China(Grant No.2024YFA1611103)the National Natural Science Foundation of China(Grant Nos.12350410367,12074360,12374128,12074386,12250410238,and 62150410438)+3 种基金the Alliance of International Science Organizations(Grant Nos.ANSO-VF-2022-03 and ANSO-VF-2024-03)Anhui Provincial Major S&T Project(Grant No.s202305a12020005)A portion of this work was supported by the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08)the High Magnetic Field Laboratory of Anhui Province under Contract No.AHHM-FX-2020-02.
文摘Fe_(3)GaTe_(2)has attracted significant interest due to its intrinsic room-temperature ferromagnetism,yet its magnetic interactions remain debated.We thoroughly investigate the magnetism of Fe_(3)GaTe_(2)using critical analysis,nitrogen–vacancy(NV)center magnetometry,and Density Function Theory(DFT).Our critical phenomenon analysis with exponents[β=0.3706(9),=1.32(6),σ=4.7(2)]and DFT calculations reveal competition between itinerant and localized spins driven by anisotropic coupling,which can be attributed to a net charge transfer of approximately 0.22 electrons from Fe^(3+)to surrounding Ge/Te atoms.As confirmed by NV center magnetometry,the ferromagnetism in Fe_(3)GaTe_(2)remains robust even in thin-layered sheet of 16 nm(corresponding to approximately 20 layers).The out-of-plane ferromagnetism in thin Fe_(3)GaTe_(2)sheets is stabilized due to the distinct spin interaction energies between intralayers(J_(1)~66.74 meV andJ_(2)~17.33 meV)and interlayers(J_(z)~3.78 meV).In addition,the constant energy contour profiles near the Fermi surface of Fe_(3)GaTe_(2)suggest the presence of both hole and electron pockets with a distorted contour around the K/K′point,indicating hexagonal trigonal warping effects.Furthermore,the layer-resolved electronic band structure uncovers a layer–valley coupling near the Fermi surface,with bands at valleys K and K′associated with different layers.These findings pave way for advanced electronic applications operating above-room-temperature.
基金U.S.Department of Energy,Office of Basic Energy Sciences,Chemical Sciences,Geosciences and Biosciences Division,Grant/Award Number:DE-FG0205ER15693。
文摘Color centers are versatile systems that generate quantum light,sense magnetic fields and produce spin-photon entanglement.We review how these properties have pushed the limits of fundamental knowledge in a variety of scientific disciplines,from rejecting local-realistic theories to sensing superconducting phase transitions.In the light of recent progress in material processing and device fabrication,we identify new opportunities for interdisciplinary fundamental discoveries in physics and geochemistry.
基金This work was supported by the European Research Council(ERC-2014-CoG project MaTissE#648779).
文摘The use of magnetic nanoparticles in nanomedicine keeps expanding and,for most applications,the nanoparticles are internalized in cells then left within,bringing the need for accurate,fast,and easy to handle methodologies to assess their behavior in the cellular environment.Herein,a benchtop-size magnetic sensor is introduced to provide real-time precise measurement of nanoparticle magnetism within living cells.The values obtained with the sensor,of cells loaded with different doses of magnetic nanoparticles,are first compared to conventional vibrating sample magnetometry(VSM),and a strong correlation remarkably validates the use of the magnetic sensor as magnetometer to determine the nanoparticle cellular uptake.The sensor is then used to monitor the progressive intracellular degradation of the nanoparticles,over days.Importantly,this real-time in situ measure is performed on a stem cell-spheroid tissue model and can run continuously on a same spheroid,with cells kept alive within.Besides,such continuous magnetic measurement of cell magnetism at the tissue scale does not impact either tissue formation,vibility,or stem cell function,including differentiation and extracellular matrix production.
