Mark P. Zic, Linda Ye, Maya H. Martinez, Ian R. Fisher
The adiabatic elastocaloric effect relates changes in the strain that a material experiences to resulting changes in its temperature. While elastocaloric materials have been utilized for cooling in room temperature applications, the use of such materials for cryogenic cooling remains relatively unexplored. Here, we use a strain load/unload technique at low temperatures, similar to those employed at room-temperature, to demonstrate a large cooling effect in TmVO$_4$. For strain changes of $1.8 cdot 10^{-3}$, the inferred cooling reaches approximately 50% of the material's starting temperature at 5 K, justifying the moniker "giant". Beyond establishing the suitability of this class of material for cryogenic elastocaloric cooling, these measurements also provide additional insight to the entropy landscape in the material as a function of strain and temperature, including the behavior proximate to the quadrupolar phase transition.
{"title":"Realization of giant elastocaloric cooling at cryogenic temperatures in TmVO$_4$ via a strain load/unload technique","authors":"Mark P. Zic, Linda Ye, Maya H. Martinez, Ian R. Fisher","doi":"arxiv-2409.06909","DOIUrl":"https://doi.org/arxiv-2409.06909","url":null,"abstract":"The adiabatic elastocaloric effect relates changes in the strain that a\u0000material experiences to resulting changes in its temperature. While\u0000elastocaloric materials have been utilized for cooling in room temperature\u0000applications, the use of such materials for cryogenic cooling remains\u0000relatively unexplored. Here, we use a strain load/unload technique at low\u0000temperatures, similar to those employed at room-temperature, to demonstrate a\u0000large cooling effect in TmVO$_4$. For strain changes of $1.8 cdot 10^{-3}$,\u0000the inferred cooling reaches approximately 50% of the material's starting\u0000temperature at 5 K, justifying the moniker \"giant\". Beyond establishing the\u0000suitability of this class of material for cryogenic elastocaloric cooling,\u0000these measurements also provide additional insight to the entropy landscape in\u0000the material as a function of strain and temperature, including the behavior\u0000proximate to the quadrupolar phase transition.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiri Houska, Mariia Zhadko, Radomir Cerstvy, Deepika Thakur, Petr Zeman
The non-equilibrium atom-by-atom growth of Cu-rich Cu-Zr thin films has been investigated by a combination of magnetron sputter deposition and molecular dynamics simulations. We focus on the role of Zr in the transition from large solid solution crystals through a nanocomposite (around ~5 at.% Zr) to a metallic glass. We find, contrary to the assumption based on equilibrium phase diagram, that in this nonequilibrium case most of the grain refinement and most of the hardness enhancement (from 2.5-3 to 4-5 GPa) takes place in the compositional range (up to ~3 at.% Zr) where many or even most Zr atoms (depending on the sputtering regime) are in the supersaturated solid solution rather than at the grain boundaries. The results are important for the design and understanding of technologically important nanostructured metallic films. In parallel, from the methodology point of view, the results include an early example of modelling the atom-by-atom nanocomposite growth.
{"title":"Role of Zr in Cu-rich single-phase and nanocomposite Cu-Zr: molecular dynamics and experimental study","authors":"Jiri Houska, Mariia Zhadko, Radomir Cerstvy, Deepika Thakur, Petr Zeman","doi":"arxiv-2409.06582","DOIUrl":"https://doi.org/arxiv-2409.06582","url":null,"abstract":"The non-equilibrium atom-by-atom growth of Cu-rich Cu-Zr thin films has been\u0000investigated by a combination of magnetron sputter deposition and molecular\u0000dynamics simulations. We focus on the role of Zr in the transition from large\u0000solid solution crystals through a nanocomposite (around ~5 at.% Zr) to a\u0000metallic glass. We find, contrary to the assumption based on equilibrium phase\u0000diagram, that in this nonequilibrium case most of the grain refinement and most\u0000of the hardness enhancement (from 2.5-3 to 4-5 GPa) takes place in the\u0000compositional range (up to ~3 at.% Zr) where many or even most Zr atoms\u0000(depending on the sputtering regime) are in the supersaturated solid solution\u0000rather than at the grain boundaries. The results are important for the design\u0000and understanding of technologically important nanostructured metallic films.\u0000In parallel, from the methodology point of view, the results include an early\u0000example of modelling the atom-by-atom nanocomposite growth.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
David A. van Nijen, Paul Procel, René A. C. M. M. van Swaaij, Miro Zeman, Olindo Isabella, Patrizio Manganiello
A thorough understanding of the small-signal response of solar cells can reveal intrinsic device characteristics and pave the way for innovations. This study investigates the impedance of crystalline silicon PN junction devices using TCAD simulations, focusing on the impact of frequency, bias voltage, and the presence of a low-high (LH) junction. It is shown that the PN junction exhibits a fixed $RC$-loop behavior at low frequencies, but undergoes relaxation in both resistance $R_j$ and capacitance $C_j$ as frequency increases. Moreover, it is revealed that the addition of a LH junction impacts the impedance by altering $R_j$, $C_j$, and the series resistance $R_s$. Contrary to conventional modeling approaches, which often include an additional $RC$-loop to represent the LH junction, this study suggests that such a representation does not represent the underlying physics, particularly the frequency-dependent behavior of $R_j$ and $C_j$.
{"title":"The nature of silicon PN junction impedance at high frequency","authors":"David A. van Nijen, Paul Procel, René A. C. M. M. van Swaaij, Miro Zeman, Olindo Isabella, Patrizio Manganiello","doi":"arxiv-2409.06749","DOIUrl":"https://doi.org/arxiv-2409.06749","url":null,"abstract":"A thorough understanding of the small-signal response of solar cells can\u0000reveal intrinsic device characteristics and pave the way for innovations. This\u0000study investigates the impedance of crystalline silicon PN junction devices\u0000using TCAD simulations, focusing on the impact of frequency, bias voltage, and\u0000the presence of a low-high (LH) junction. It is shown that the PN junction\u0000exhibits a fixed $RC$-loop behavior at low frequencies, but undergoes\u0000relaxation in both resistance $R_j$ and capacitance $C_j$ as frequency\u0000increases. Moreover, it is revealed that the addition of a LH junction impacts\u0000the impedance by altering $R_j$, $C_j$, and the series resistance $R_s$.\u0000Contrary to conventional modeling approaches, which often include an additional\u0000$RC$-loop to represent the LH junction, this study suggests that such a\u0000representation does not represent the underlying physics, particularly the\u0000frequency-dependent behavior of $R_j$ and $C_j$.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Albert Salmi, Miloslav Capek, Lukas Jelinek, Anu Lehtovuori, Ville Viikari
This paper introduces a framework for synthesizing reactively loaded antennas and antenna arrays. The framework comprises two main components: computing the fundamental bound using the semi-definite relaxation and finding a realizable solution via optimization on a Riemannian manifold. The embedded element patterns are subject to the optimization with two distinct goals under study: focusing the radiation in a single direction or synthesizing patterns with desired shapes. The reactive terminations of passive antenna elements serve as optimization variables. We demonstrate the framework using a connected bowtie-slot antenna and antenna array with both beam-focusing and beam-shaping targets. The tests show that the optimization on the Riemannian manifold yields superior results compared to existing methods, such as the genetic algorithm. This is particularly evident in the most complex and extensive problem, which requires the synthesis of shaped embedded element patterns for a sparse reactively loaded antenna array with a limited field of view.
{"title":"Optimization of Embedded Element Patterns of Reactively Loaded Antenna Arrays","authors":"Albert Salmi, Miloslav Capek, Lukas Jelinek, Anu Lehtovuori, Ville Viikari","doi":"arxiv-2409.06291","DOIUrl":"https://doi.org/arxiv-2409.06291","url":null,"abstract":"This paper introduces a framework for synthesizing reactively loaded antennas\u0000and antenna arrays. The framework comprises two main components: computing the\u0000fundamental bound using the semi-definite relaxation and finding a realizable\u0000solution via optimization on a Riemannian manifold. The embedded element\u0000patterns are subject to the optimization with two distinct goals under study:\u0000focusing the radiation in a single direction or synthesizing patterns with\u0000desired shapes. The reactive terminations of passive antenna elements serve as\u0000optimization variables. We demonstrate the framework using a connected\u0000bowtie-slot antenna and antenna array with both beam-focusing and beam-shaping\u0000targets. The tests show that the optimization on the Riemannian manifold yields\u0000superior results compared to existing methods, such as the genetic algorithm.\u0000This is particularly evident in the most complex and extensive problem, which\u0000requires the synthesis of shaped embedded element patterns for a sparse\u0000reactively loaded antenna array with a limited field of view.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We fabricated a wedge-shaped Pt/Co/Pt device with perpendicular magnetic anisotropy and manifested that the Co magnetization can be solely switched by spin-orbit torque without any magnetic field. Similar to the synaptic weight, we observed that the state of Co magnetization (presented by the anomalous Hall resistance RH) of the wedged Pt/Co/Pt device can be tuned continuously with a large number of nonvolatile levels by applied pulse currents. Furthermore, we studied the synaptic plasticity of the wedged Pt/Co/Pt device, including the excitatory postsynaptic potentials or inhibitory postsynaptic potentials and spiking-time-dependent plasticity. The work elucidates the promise of the wedged Pt/Co/Pt device as a candidate for a new type of artificial synaptic device that is induced by a spin current and paves a substantial pathway toward the combination of spintronics and synaptic devices.
{"title":"Mimicking synaptic plasticity with wedged Pt/Co/Pt spin-orbit torque device","authors":"Shiwei Chen, Mishra Rahul, Huanjian Chen, Hyunsoo Yang, Xuepeng Qiu","doi":"arxiv-2409.06286","DOIUrl":"https://doi.org/arxiv-2409.06286","url":null,"abstract":"We fabricated a wedge-shaped Pt/Co/Pt device with perpendicular magnetic\u0000anisotropy and manifested that the Co magnetization can be solely switched by\u0000spin-orbit torque without any magnetic field. Similar to the synaptic weight,\u0000we observed that the state of Co magnetization (presented by the anomalous Hall\u0000resistance RH) of the wedged Pt/Co/Pt device can be tuned continuously with a\u0000large number of nonvolatile levels by applied pulse currents. Furthermore, we\u0000studied the synaptic plasticity of the wedged Pt/Co/Pt device, including the\u0000excitatory postsynaptic potentials or inhibitory postsynaptic potentials and\u0000spiking-time-dependent plasticity. The work elucidates the promise of the\u0000wedged Pt/Co/Pt device as a candidate for a new type of artificial synaptic\u0000device that is induced by a spin current and paves a substantial pathway toward\u0000the combination of spintronics and synaptic devices.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bernard Dieny, Sanjeev Aggarwal, Vinayak Bharat Naik, Sebastien Couet, Thomas Coughlin, Shunsuke Fukami, Kevin Garello, Jack Guedj, Jean Anne C. Incorvia, Laurent Lebrun, Kyung-Jin Lee, Daniele Leonelli, Yonghwan Noh, Siamak Salimy, Steven Soss, Luc Thomas, Weigang Wang, Daniel Worledge
This application note discusses the working principle of spin-transfer torque magnetoresistive random access memory (STT-MRAM) and the impact that magnetic fields can have on STT-MRAM operation. Sources of magnetic field and typical magnitudes of magnetic fields are given. Based on the magnitude of commonly encountered external magnetic fields, we show below that magnetic immunity of STT-MRAM is sufficient for most uses once the chip is mounted on a printed circuit board (PCB) or inserted in its working environment. This statement is supported by the experience acquired during 60 years of use of magnetic hard disk drives (HDD) including 20 years of HDD with readers comprising magnetic tunnel junctions, 20+ years of use of magnetic field sensors as position encoders in automotive industry and 15+ years of use of MRAM. Mainly during chip handling does caution need to be exercised to avoid exposing the chip to excessively high magnetic fields.
{"title":"Impact of external magnetic fields on STT-MRAM","authors":"Bernard Dieny, Sanjeev Aggarwal, Vinayak Bharat Naik, Sebastien Couet, Thomas Coughlin, Shunsuke Fukami, Kevin Garello, Jack Guedj, Jean Anne C. Incorvia, Laurent Lebrun, Kyung-Jin Lee, Daniele Leonelli, Yonghwan Noh, Siamak Salimy, Steven Soss, Luc Thomas, Weigang Wang, Daniel Worledge","doi":"arxiv-2409.05584","DOIUrl":"https://doi.org/arxiv-2409.05584","url":null,"abstract":"This application note discusses the working principle of spin-transfer torque\u0000magnetoresistive random access memory (STT-MRAM) and the impact that magnetic\u0000fields can have on STT-MRAM operation. Sources of magnetic field and typical\u0000magnitudes of magnetic fields are given. Based on the magnitude of commonly\u0000encountered external magnetic fields, we show below that magnetic immunity of\u0000STT-MRAM is sufficient for most uses once the chip is mounted on a printed\u0000circuit board (PCB) or inserted in its working environment. This statement is\u0000supported by the experience acquired during 60 years of use of magnetic hard\u0000disk drives (HDD) including 20 years of HDD with readers comprising magnetic\u0000tunnel junctions, 20+ years of use of magnetic field sensors as position\u0000encoders in automotive industry and 15+ years of use of MRAM. Mainly during\u0000chip handling does caution need to be exercised to avoid exposing the chip to\u0000excessively high magnetic fields.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kai Wen, Huijin Chen, Xu Yan, Zejian Ren, Chengdong He, Elnur Hajiyev, Preston Tsz Fung Wong, Gyu-Boong Jo
We outline an experimental setup for efficiently preparing a tweezer array of $^{88}$Sr atoms. Our setup uses permanent magnets to maintain a steady-state two-dimensional magneto-optical trap (MOT) which results in a loading rate of up to $10^{8}$ s$^{-1}$ at 5 mK for the three-dimensional blue MOT. This enables us to trap $2times10^{6}$ $^{88}$Sr atoms at 2 $mu$K in a narrow-line red MOT with the $^{1}$S$_{0}$ $rightarrow$ $^{3}$P$_{1}$ intercombination transition at 689 nm. With the Sisyphus cooling and pairwise loss processes, single atoms are trapped and imaged in 813 nm optical tweezers, exhibiting a lifetime of 2.5 minutes. We further investigate the survival fraction of a single atom in the tweezers and characterize the optical tweezer array using a release and recapture technique. Our platform paves the way for potential applications in atomic clocks, precision measurements, and quantum simulations.
{"title":"Apparatus for producing single strontium atoms in an optical tweezer array","authors":"Kai Wen, Huijin Chen, Xu Yan, Zejian Ren, Chengdong He, Elnur Hajiyev, Preston Tsz Fung Wong, Gyu-Boong Jo","doi":"arxiv-2409.05361","DOIUrl":"https://doi.org/arxiv-2409.05361","url":null,"abstract":"We outline an experimental setup for efficiently preparing a tweezer array of\u0000$^{88}$Sr atoms. Our setup uses permanent magnets to maintain a steady-state\u0000two-dimensional magneto-optical trap (MOT) which results in a loading rate of\u0000up to $10^{8}$ s$^{-1}$ at 5 mK for the three-dimensional blue MOT. This\u0000enables us to trap $2times10^{6}$ $^{88}$Sr atoms at 2 $mu$K in a narrow-line\u0000red MOT with the $^{1}$S$_{0}$ $rightarrow$ $^{3}$P$_{1}$ intercombination\u0000transition at 689 nm. With the Sisyphus cooling and pairwise loss processes,\u0000single atoms are trapped and imaged in 813 nm optical tweezers, exhibiting a\u0000lifetime of 2.5 minutes. We further investigate the survival fraction of a\u0000single atom in the tweezers and characterize the optical tweezer array using a\u0000release and recapture technique. Our platform paves the way for potential\u0000applications in atomic clocks, precision measurements, and quantum simulations.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quench protection of full-size high-field accelerator magnets poses significant challenges. Maintaining the hot-spot temperature and peak voltage-to-ground within acceptable limits requires a protection system that quickly transitions most of the coil turns to the normal state. Existing magnet protection technologies, such as quench protection heaters or the Coupling Loss Induced Quench system (CLIQ), have been successfully applied. However, they both present shortcomings since they require either thin insulation between the heaters and the magnet conductor or direct electrical connections to the magnet coil. A novel quench protection method, Energy Shift with Coupling (ESC), is presented which can achieve excellent quench protection performance without the above-mentioned drawbacks. ESC relies on normal-conducting auxiliary coils strongly magnetically coupled with the magnet coils to protect. Upon quench detection capacitive units connected across such coils introduce a high current change in the auxiliary coils causing a rapid shift of magnet stored energy from the magnet coils to the auxiliary coils. This has three beneficial effects: sudden reduction of ohmic loss in the normal zone of the magnet conductor, introduction of high transient losses in the magnet conductor, thus causing a quick transition to the normal state, and extraction of a part of the magnet stored energy to the auxiliary coils. The applicability of the ESC concept on an existing magnet design is analyzed with electromagnetic and thermal transient simulations performed with the STEAM-LEDET program. The advantages and disadvantages of ESC are discussed and compared to other conventional quench protection methods. Simulation results show that ESC can be applied to protect full-scale magnets with reasonable requirements in terms of size and location of the auxiliary coils and of capacitive unit parameters.
{"title":"Energy Shift with Coupling (ESC): a new quench protection method","authors":"Emmanuele Ravaioli, Arjan Verweij, Mariusz Wozniak","doi":"arxiv-2409.05446","DOIUrl":"https://doi.org/arxiv-2409.05446","url":null,"abstract":"Quench protection of full-size high-field accelerator magnets poses\u0000significant challenges. Maintaining the hot-spot temperature and peak\u0000voltage-to-ground within acceptable limits requires a protection system that\u0000quickly transitions most of the coil turns to the normal state. Existing magnet\u0000protection technologies, such as quench protection heaters or the Coupling Loss\u0000Induced Quench system (CLIQ), have been successfully applied. However, they\u0000both present shortcomings since they require either thin insulation between the\u0000heaters and the magnet conductor or direct electrical connections to the magnet\u0000coil. A novel quench protection method, Energy Shift with Coupling (ESC), is\u0000presented which can achieve excellent quench protection performance without the\u0000above-mentioned drawbacks. ESC relies on normal-conducting auxiliary coils\u0000strongly magnetically coupled with the magnet coils to protect. Upon quench\u0000detection capacitive units connected across such coils introduce a high current\u0000change in the auxiliary coils causing a rapid shift of magnet stored energy\u0000from the magnet coils to the auxiliary coils. This has three beneficial\u0000effects: sudden reduction of ohmic loss in the normal zone of the magnet\u0000conductor, introduction of high transient losses in the magnet conductor, thus\u0000causing a quick transition to the normal state, and extraction of a part of the\u0000magnet stored energy to the auxiliary coils. The applicability of the ESC\u0000concept on an existing magnet design is analyzed with electromagnetic and\u0000thermal transient simulations performed with the STEAM-LEDET program. The\u0000advantages and disadvantages of ESC are discussed and compared to other\u0000conventional quench protection methods. Simulation results show that ESC can be\u0000applied to protect full-scale magnets with reasonable requirements in terms of\u0000size and location of the auxiliary coils and of capacitive unit parameters.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mariusz Mrózek, Adam Filipkowski, Wojciech Gawlik, Ryszard Buczyński, Adam M. Wojciechowski, Mariusz Klimczak
We employ an optical fiber doped with randomly oriented fluorescent sub-micron diamonds and the novel zero-field resonance protocol to collect information on the localization and orientation of a magnetic-field source and its distribution. Many previous demonstrations of diamond-based magnetic field sensing achieved ultrahigh sensitivities down to the fT range warranted by manipulating spin states of the diamond nitrogen vacancy (NV) centers with externally applied radio or microwaves. The application of such oscillating fields is problematic in distributed magnetic-field measurements and may be incompatible with specific targets. Instead of relying on these approaches, we leveraged cross-relaxations of particular spin-state populations of the NV center under a magnetic field, thus observing zero-field resonances and making external radio frequency fields redundant. Combined with an optical fiber sensitive to the magnetic field along its entire length, remote sensing was realized that returned information on the spatial field distribution without using any moving mechanical elements in the detection system. Variation of the spatial parameters of the investigated field was achieved simply by controlling the current in a pair of induction coils easily integrable with optical fibers without limiting the fiber-specific functionality of the optical readout taking place at a fixed location at the optical fiber output. Lifting of the requirements related to the mechanical scanning of the fiber, the application of external fields, and the orientation of the NV centers against the measured field mark a very practical step forward in optically driven magnetic field sensing, not easily achievable with earlier implementations.
我们采用掺杂了随机定向荧光亚微米级金刚石的光纤和新颖的零场共振协议来收集有关磁场源的定位和定向及其分布的信息。以前的许多基于金刚石的磁场感应演示都通过利用外部施加的无线电或微波操纵金刚石氮空位（NV）中心的自旋态，实现了低至 fT 范围的超高灵敏度。这种振荡场的应用在分布式磁场测量中存在问题，而且可能与特定目标不兼容。我们没有依赖这些方法，而是利用磁场下 NV 中心特定自旋态群的交叉松弛，从而观测到零场共振，使外部射频场成为多余。结合对整个长度上的磁场敏感的光纤，实现了遥感，在探测系统中不使用任何移动机械元件的情况下，就能返回空间磁场分布的信息。只需控制一对感应线圈中的电流，就能实现被测磁场空间参数的变化，而无需限制光纤输出端固定位置的光读出功能。取消了与光纤机械扫描、外部磁场应用和 NV 中心对测量磁场的定向有关的要求，标志着光驱动磁场感应技术向前迈出了非常实用的一步，这在以前的实现方法中是不容易做到的。
{"title":"Localization of macroscopic sources of magnetic field using optical fibers doped with NV-rich sub-micron diamonds and zero-field resonance","authors":"Mariusz Mrózek, Adam Filipkowski, Wojciech Gawlik, Ryszard Buczyński, Adam M. Wojciechowski, Mariusz Klimczak","doi":"arxiv-2409.05452","DOIUrl":"https://doi.org/arxiv-2409.05452","url":null,"abstract":"We employ an optical fiber doped with randomly oriented fluorescent\u0000sub-micron diamonds and the novel zero-field resonance protocol to collect\u0000information on the localization and orientation of a magnetic-field source and\u0000its distribution. Many previous demonstrations of diamond-based magnetic field\u0000sensing achieved ultrahigh sensitivities down to the fT range warranted by\u0000manipulating spin states of the diamond nitrogen vacancy (NV) centers with\u0000externally applied radio or microwaves. The application of such oscillating\u0000fields is problematic in distributed magnetic-field measurements and may be\u0000incompatible with specific targets. Instead of relying on these approaches, we\u0000leveraged cross-relaxations of particular spin-state populations of the NV\u0000center under a magnetic field, thus observing zero-field resonances and making\u0000external radio frequency fields redundant. Combined with an optical fiber\u0000sensitive to the magnetic field along its entire length, remote sensing was\u0000realized that returned information on the spatial field distribution without\u0000using any moving mechanical elements in the detection system. Variation of the\u0000spatial parameters of the investigated field was achieved simply by controlling\u0000the current in a pair of induction coils easily integrable with optical fibers\u0000without limiting the fiber-specific functionality of the optical readout taking\u0000place at a fixed location at the optical fiber output. Lifting of the\u0000requirements related to the mechanical scanning of the fiber, the application\u0000of external fields, and the orientation of the NV centers against the measured\u0000field mark a very practical step forward in optically driven magnetic field\u0000sensing, not easily achievable with earlier implementations.","PeriodicalId":501083,"journal":{"name":"arXiv - PHYS - Applied Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142177776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Saravanan Lakshmanan, Cristian Romanque, Mario Mery, Manivel Raja Muthuvel, Nanhe Kumar Gupta, Carlos Garcia
We investigated the effects of annealing temperatures (TA) on a Pd (5 nm)/CoFeB (10 nm)/Pd (3 nm)/Ta (10 nm) multilayer structure. The as-deposited sample showed an amorphous state with in-plane uniaxial magnetic anisotropy (UMA), resulting in low coercivity and moderate damping constant ({alpha}) values. Increasing TA led to crystallization, forming bcc-CoFe (110) crystals, which increased in-plane coercivity and introduced isotropic magnetic anisotropy, slightly reducing the {alpha}. The two-fold UMA persists up to 600 C, and the thermal stability of the in-plane magnetic anisotropy remains intact even TA = 700 C. The TA significantly influenced the magnetic properties such as in-plane saturation magnetization (Ms//), in-plane and out-of-plane coercivities, and in-plane effective magnetic anisotropy energy density (Keff). Above 600 C, Keff decreased, indicating a transition towards uniaxial perpendicular magnetic anisotropy. Interfacial oxidation and diffusion from the Ta capping layer to the Pd/CoFeB/Pd interfaces were observed, influencing chemical bonding states. Annealing at 700 C, reduced oxygen within TaOx through a redox reaction involving Ta crystallization, forming TaB, PdO, and BOx states. Ferromagnetic resonance spectra analysis indicated variations in resonance field (Hr) due to local chemical environments. The {alpha} reduction, reaching a minimum at 300 C annealing, was attributed to reduced structural disorder from inhomogeneities. Tailoring magnetic anisotropy and spin dynamic properties in Pd/CoFeB/Pd/Ta structures through TA-controlled oxygen diffusion/oxidation highlights their potential for SOT, DMI, and magnetic skyrmion-based spintronic devices.
我们研究了退火温度（TA）对钯（5 nm）/钴铁硼（10 nm）/钯（3 nm）/钽（10 nm）多层结构的影响。沉积样品呈无定形状态，具有面内单轴磁各向异性（UMA），因此矫顽力低，阻尼常数（{alpha}）值适中。增加 TA 会导致结晶，形成 bcc-CoFe (110) 晶体，从而提高了面内矫顽力，并引入了各向同性磁各向异性，略微降低了{alpha}。两倍 UMA 一直持续到 600 C，即使 TA = 700 C，面内磁各向异性的热稳定性也保持不变。TA 对面内饱和磁化（Ms//）、面内和面外矫顽力以及面内有效磁各向异性能量密度（Keff）等磁性能有显著影响。在 600 C 以上，Keff 下降，表明向单轴垂直磁各向异性过渡。观察到了从 Ta 盖层到 Pd/CoFeB/Pd 界面的界面氧化和扩散，这影响了化学键状态。在 700 C 退火时，通过涉及 Ta 结晶的氧化还原反应还原了 TaOx 中的氧，形成了 TaB、PdO 和 BOx 态。铁磁共振光谱分析表明，共振场（Hr）因局部化学环境而变化。{alpha}还原在 300 C 退火时达到最小值，这归因于非均质性导致的结构紊乱的减少。通过 TA 控制的氧扩散/氧化作用来定制 Pd/CoFeB/Pd/Ta 结构中的磁各向异性和自旋动态特性，凸显了它们在基于 SOT、DMI 和磁天幕的自旋电子器件方面的潜力。
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