Two monolithic edge-emitting passively mode-locked InAs/InGaAs semiconductor quantum dot lasers generating ps optical pulses at repetition rates of 10 GHz and optical frequency combs centered at 1260 nm are mutually coupled in an all-optical passive synchronization experiment. The two lasers, with different free-running repetition rates, are coupled through a long delay fiber path, they synchronize, and generate optical pulse trains with identical repetition rates in a wide range of experimental conditions (optical frequency, optical delay, and coupling strength). The common repetition rate can be easily fine-tuned with the control of the external coupling path length. In synchronized state, both lasers operate with significantly reduced timing jitter with respect to their free-running values. Finally, under specific conditions, the repetition rate locking is accompanied by partial mutual coherence between the lasers, as indicated by the formation of interferometric fringes.
{"title":"Experimental demonstration of synchronization between two quantum dot passively mode-locked laser frequency combs utilizing bidirectional optical coupling","authors":"Daniel Bita, Iraklis Simos, Christos Simos","doi":"10.1063/5.0246902","DOIUrl":"https://doi.org/10.1063/5.0246902","url":null,"abstract":"Two monolithic edge-emitting passively mode-locked InAs/InGaAs semiconductor quantum dot lasers generating ps optical pulses at repetition rates of 10 GHz and optical frequency combs centered at 1260 nm are mutually coupled in an all-optical passive synchronization experiment. The two lasers, with different free-running repetition rates, are coupled through a long delay fiber path, they synchronize, and generate optical pulse trains with identical repetition rates in a wide range of experimental conditions (optical frequency, optical delay, and coupling strength). The common repetition rate can be easily fine-tuned with the control of the external coupling path length. In synchronized state, both lasers operate with significantly reduced timing jitter with respect to their free-running values. Finally, under specific conditions, the repetition rate locking is accompanied by partial mutual coherence between the lasers, as indicated by the formation of interferometric fringes.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"58 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443886","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhao Pan, Sergey A. Nikolaev, Jie Zhang, Maocai Pi, Mengqi Ye, Qiumin Liu, Xubin Ye, Xiao Wang, Takumi Nishikubo, Shogo Kawaguchi, Masaki Azuma, Youwen Long
PbTiO3 is a typical perovskite-type ferroelectric that shows unique negative thermal expansion (NTE) from room temperature to its Curie temperature (α¯V = −1.99 × 10−5 K−1, 300–763 K). It is widely accepted that enhanced NTE can be achieved in PbTiO3-based ferroelectrics by improving the tetragonality of PbTiO3 (c/a = 1.064) through chemical substitutions. Nevertheless, most substituted PbTiO3-based ferroelectrics exhibit reduced tetragonality and weakened NTE, while enhanced NTE has only been achieved in those materials with enhanced tetragonality so far. Herein, we report on (1 − x)PbTiO3-xBiAlO3 solid solutions for which we observe reduced tetragonality accompanied by an unusual enhanced NTE (c/a = 1.057, α¯V = −2.23 × 10−5 K−1, 300–740 K), without much degradation of the NTE temperature range of pristine PbTiO3 upon doping. The present study provides an example of unusual enhanced NTE accompanied by reduced tetragonality in PbTiO3-based perovskites, which will extend the scope of NTE in PbTiO3-based ferroelectrics and shed light on the understanding of enhanced NTE in PbTiO3 family.
{"title":"Extend the scope of negative thermal expansion in PbTiO3-based perovskites","authors":"Zhao Pan, Sergey A. Nikolaev, Jie Zhang, Maocai Pi, Mengqi Ye, Qiumin Liu, Xubin Ye, Xiao Wang, Takumi Nishikubo, Shogo Kawaguchi, Masaki Azuma, Youwen Long","doi":"10.1063/5.0253686","DOIUrl":"https://doi.org/10.1063/5.0253686","url":null,"abstract":"PbTiO3 is a typical perovskite-type ferroelectric that shows unique negative thermal expansion (NTE) from room temperature to its Curie temperature (α¯V = −1.99 × 10−5 K−1, 300–763 K). It is widely accepted that enhanced NTE can be achieved in PbTiO3-based ferroelectrics by improving the tetragonality of PbTiO3 (c/a = 1.064) through chemical substitutions. Nevertheless, most substituted PbTiO3-based ferroelectrics exhibit reduced tetragonality and weakened NTE, while enhanced NTE has only been achieved in those materials with enhanced tetragonality so far. Herein, we report on (1 − x)PbTiO3-xBiAlO3 solid solutions for which we observe reduced tetragonality accompanied by an unusual enhanced NTE (c/a = 1.057, α¯V = −2.23 × 10−5 K−1, 300–740 K), without much degradation of the NTE temperature range of pristine PbTiO3 upon doping. The present study provides an example of unusual enhanced NTE accompanied by reduced tetragonality in PbTiO3-based perovskites, which will extend the scope of NTE in PbTiO3-based ferroelectrics and shed light on the understanding of enhanced NTE in PbTiO3 family.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"49 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Terahertz technology is poised to revolutionize next-generation wireless communication systems, such as 5G-A and 6G, by addressing the growing need for efficient electromagnetic wave modulation in the terahertz frequency band. In this study, we present a reflective metasurface comprising dual metal layers and a tunable liquid crystal medium, designed to achieve dynamic linear-to-circular polarization conversion. Experimental results demonstrate polarization conversion across three frequency bands: 248–254, 265–278, and 287–292 GHz. Furthermore, left-hand circular polarization (LHCP)-to-right-hand circular polarization (RHCP) switching is achieved at 248–254 and 287–292 GHz, with a stable RHCP state observed at 265–278 GHz. These findings validate the device's ability to dynamically control polarization states through applied bias voltage. By enabling precise and flexible modulation, this metasurface provides a scalable and efficient solution for reconfigurable intelligent surfaces, paving the way for advanced terahertz communication systems in future wireless networks.
{"title":"Tri-band terahertz polarization reconfigurable reflective metasurface based on liquid crystal","authors":"Qi Xie, Bao Zhang, Shui Liu, Jingxia Qiang, Yamei Zhang, Feng Xu","doi":"10.1063/5.0251461","DOIUrl":"https://doi.org/10.1063/5.0251461","url":null,"abstract":"Terahertz technology is poised to revolutionize next-generation wireless communication systems, such as 5G-A and 6G, by addressing the growing need for efficient electromagnetic wave modulation in the terahertz frequency band. In this study, we present a reflective metasurface comprising dual metal layers and a tunable liquid crystal medium, designed to achieve dynamic linear-to-circular polarization conversion. Experimental results demonstrate polarization conversion across three frequency bands: 248–254, 265–278, and 287–292 GHz. Furthermore, left-hand circular polarization (LHCP)-to-right-hand circular polarization (RHCP) switching is achieved at 248–254 and 287–292 GHz, with a stable RHCP state observed at 265–278 GHz. These findings validate the device's ability to dynamically control polarization states through applied bias voltage. By enabling precise and flexible modulation, this metasurface provides a scalable and efficient solution for reconfigurable intelligent surfaces, paving the way for advanced terahertz communication systems in future wireless networks.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"64 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this Letter, the Venturi effect is introduced to change the vibration behaviors of a downwind bluff body and a piezoelectric wind-induced vibration energy harvester using the Venturi effect (VE-PWVEH) is reported to offer an alternative solution to enable a high-performance downwind PWVEH. Also, the power generation characteristics were readily adjusted by the flow channel forming the Venturi effect without modifying the PWVEH structure. So, the VE-PWVEH could possess both great power-generating capability at low wind speed and strong robustness at high wind speed. The results demonstrated that both the output voltage and cut-in wind speed were affected by the attack angle of two rectangular plates used for stimulating the constricted channel. There was an optimal attack angle of 60° where a maximum peak voltage of the VE-PWVEH was increased by 621% and the cut-in wind speed was reduced by 171% compared with the harvester without the Venturi effect. Besides, it demonstrated the VE-PWVEH could achieve an output power of 0.863 mW and illuminate about 120 blue LEDs in series. The introduction of the Venturi effect provides a simple and viable method of flow field disturbance to tune the performance of PWVEHs.
{"title":"A piezoelectric wind-induced vibration energy harvester via the Venturi effect","authors":"Mengsong Zhu, Zhenli Kuang, Weilin Liao, Jinbo Zhang, Linfei Fu, Zhonghua Zhang, Junwu Kan","doi":"10.1063/5.0249187","DOIUrl":"https://doi.org/10.1063/5.0249187","url":null,"abstract":"In this Letter, the Venturi effect is introduced to change the vibration behaviors of a downwind bluff body and a piezoelectric wind-induced vibration energy harvester using the Venturi effect (VE-PWVEH) is reported to offer an alternative solution to enable a high-performance downwind PWVEH. Also, the power generation characteristics were readily adjusted by the flow channel forming the Venturi effect without modifying the PWVEH structure. So, the VE-PWVEH could possess both great power-generating capability at low wind speed and strong robustness at high wind speed. The results demonstrated that both the output voltage and cut-in wind speed were affected by the attack angle of two rectangular plates used for stimulating the constricted channel. There was an optimal attack angle of 60° where a maximum peak voltage of the VE-PWVEH was increased by 621% and the cut-in wind speed was reduced by 171% compared with the harvester without the Venturi effect. Besides, it demonstrated the VE-PWVEH could achieve an output power of 0.863 mW and illuminate about 120 blue LEDs in series. The introduction of the Venturi effect provides a simple and viable method of flow field disturbance to tune the performance of PWVEHs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"36 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wearable thermoelectric generators (WTEGs) are of significance in the conversion of body heat into electricity for the purpose of powering wearable electronic devices. Two-dimensional (2D) transition metal dichalcogenides (TMDCs) exhibit exceptional thermoelectric power factors and mechanical stability, making them promising flexible thermoelectric materials. However, the output voltage of the present TMDC-based WTEGs remains at a relatively low level. In this study, we precisely modulate the electronic structure of titanium disulfide (TiS2) nanosheets in a restacked film by surface modification, leading to the decoupling phenomenon of a simultaneous rise in the electrical conductivity and the Seebeck coefficient. This method enhances the thermoelectric power factor by approximately 14 times compared to pre-modified samples. We fabricated a flexible self-reassembly WTEG using 1T-phase molybdenum disulfide (MoS2) nanosheets as p-type material and modified TiS2 nanosheets as an n-type material. The generator achieved a voltage output of approximately 15 mV while harvesting heat from the human arm, showcasing its potential for practical applications.
{"title":"Self-reassembly wearable thermoelectric generator using surface-modified TMDCs","authors":"Yaocheng Yang, Huihui Huang","doi":"10.1063/5.0244224","DOIUrl":"https://doi.org/10.1063/5.0244224","url":null,"abstract":"Wearable thermoelectric generators (WTEGs) are of significance in the conversion of body heat into electricity for the purpose of powering wearable electronic devices. Two-dimensional (2D) transition metal dichalcogenides (TMDCs) exhibit exceptional thermoelectric power factors and mechanical stability, making them promising flexible thermoelectric materials. However, the output voltage of the present TMDC-based WTEGs remains at a relatively low level. In this study, we precisely modulate the electronic structure of titanium disulfide (TiS2) nanosheets in a restacked film by surface modification, leading to the decoupling phenomenon of a simultaneous rise in the electrical conductivity and the Seebeck coefficient. This method enhances the thermoelectric power factor by approximately 14 times compared to pre-modified samples. We fabricated a flexible self-reassembly WTEG using 1T-phase molybdenum disulfide (MoS2) nanosheets as p-type material and modified TiS2 nanosheets as an n-type material. The generator achieved a voltage output of approximately 15 mV while harvesting heat from the human arm, showcasing its potential for practical applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"11 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. A. Yianni, A. Stacey, D. L. Creedon, K. Xing, A. K. Schenk, C. I. Pakes
The use of a transition metal catalyzed thermochemical etching method for improving the carrier transport properties of the near-surface two-dimensional (2D) hole gas in surface transfer-doped hydrogen-terminated (111) diamond is demonstrated. Using Ni0.8Cr0.2 films deposited and annealed to a temperature of 900 °C, with up to three etch cycles, preferential (111) surface etching produces large terraces exceeding 10 μm in size with a surface microroughness, σRMS2λ, that is two orders of magnitude lower than for the pre-etched (111) surface. Magnetotransport measurements on hydrogen-terminated Hall bars engineered on the pre- and post-etched surfaces and rendered conductive by the adsorbed water layer formed on exposure to ambient conditions demonstrate that this etching causes an improvement in the hole mobility by an order of magnitude, resulting in a measured sheet resistivity of 1.04 kΩ/sq at a temperature of 4.2 K without gating.
{"title":"Enhancement to the conductivity of surface transfer-doped (111) diamond through thermochemical surface etching","authors":"S. A. Yianni, A. Stacey, D. L. Creedon, K. Xing, A. K. Schenk, C. I. Pakes","doi":"10.1063/5.0245506","DOIUrl":"https://doi.org/10.1063/5.0245506","url":null,"abstract":"The use of a transition metal catalyzed thermochemical etching method for improving the carrier transport properties of the near-surface two-dimensional (2D) hole gas in surface transfer-doped hydrogen-terminated (111) diamond is demonstrated. Using Ni0.8Cr0.2 films deposited and annealed to a temperature of 900 °C, with up to three etch cycles, preferential (111) surface etching produces large terraces exceeding 10 μm in size with a surface microroughness, σRMS2λ, that is two orders of magnitude lower than for the pre-etched (111) surface. Magnetotransport measurements on hydrogen-terminated Hall bars engineered on the pre- and post-etched surfaces and rendered conductive by the adsorbed water layer formed on exposure to ambient conditions demonstrate that this etching causes an improvement in the hole mobility by an order of magnitude, resulting in a measured sheet resistivity of 1.04 kΩ/sq at a temperature of 4.2 K without gating.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"23 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Gossing, E. Spetzler, A. Kittmann, F. Niekiel, M. Jovičević-Klug, M. Path, D. Meyners, T. Lisec, B. Gojdka, F. Lofink, J. McCord
Single magnetic domain soft magnetic films are the basis for many magnetic field sensing applications. The absence of magnetic domain walls reduces magnetic noise, which is relevant for magnetic sensing layers and supporting structures such as magnetic shields and flux concentrators. Here, the use of wafer-level integrated NdFeB micromagnets for on-chip field biasing of soft magnetic submicrometer thick layers for magnetic domain control is presented. Effective bias field strengths are modeled and experimentally evaluated using a magnetooptical indicator film technique. Single magnetic domain behavior in the soft magnetic layers is demonstrated. Effects of the granular micromagnet structure on the magnetic field homogeneity are discussed. The demonstrated integrated magnetic biasing scheme is applicable to various magnetic layer-based field sensing devices benefiting from single magnetic domain behavior.
{"title":"Wafer-level magnetic field biased single domain soft magnetic layers by integrated NdFeB micromagnets","authors":"F. Gossing, E. Spetzler, A. Kittmann, F. Niekiel, M. Jovičević-Klug, M. Path, D. Meyners, T. Lisec, B. Gojdka, F. Lofink, J. McCord","doi":"10.1063/5.0244994","DOIUrl":"https://doi.org/10.1063/5.0244994","url":null,"abstract":"Single magnetic domain soft magnetic films are the basis for many magnetic field sensing applications. The absence of magnetic domain walls reduces magnetic noise, which is relevant for magnetic sensing layers and supporting structures such as magnetic shields and flux concentrators. Here, the use of wafer-level integrated NdFeB micromagnets for on-chip field biasing of soft magnetic submicrometer thick layers for magnetic domain control is presented. Effective bias field strengths are modeled and experimentally evaluated using a magnetooptical indicator film technique. Single magnetic domain behavior in the soft magnetic layers is demonstrated. Effects of the granular micromagnet structure on the magnetic field homogeneity are discussed. The demonstrated integrated magnetic biasing scheme is applicable to various magnetic layer-based field sensing devices benefiting from single magnetic domain behavior.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"13 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Two-dimensional (2D) transition metal dichalcogenides and their alloys provide a unique platform for exploring interlayer charge transfer in van der Waals heterostructures. These structures are crucial for advancing the next-generation electronic, optoelectronic, and quantum devices. In this study, interlayer charge transfer in heterostructures composed of MoSe2, MoS2, and their alloy, MoSSe, is investigated using transient absorption, Raman, and photoluminescence spectroscopy. The experimental results reveal that electron transfer in the alloy heterostructures, MoSSe/MoS2 and MoSe2/MoSSe, is faster than in the pure MoSe2/MoS2 heterostructure, despite the smaller conduction band offsets of the alloy systems. Raman spectroscopy confirms that alloy layers support phonon modes matching those of the pure layers, aligning with theoretical models of phonon-assisted interlayer charge transfer. Additionally, efficient hole transfer is observed in both alloy heterostructures. The findings suggest transition metal dichalcogenides alloys can be used for engineering heterostructures with desired charge transfer properties. By leveraging compositionally tunable band gaps and optical properties, alloy-based heterostructures offer opportunities for designing tailored materials suitable for diverse applications such as photodetectors, light-emitting devices, and flexible electronics. Moreover, the ultrafast charge transfer observed in these systems provides insights into the fundamental mechanisms governing interlayer interactions in 2D materials.
{"title":"Charge transfer in transition metal dichalcogenide alloy heterostructures","authors":"Fangying Ren, Dawei He, Xiaoxian Zhang, Guili Li, Xiaojing Liu, Jiarong Wang, Kun Zhao, Jiaqi He, Yongsheng Wang, Hui Zhao","doi":"10.1063/5.0255439","DOIUrl":"https://doi.org/10.1063/5.0255439","url":null,"abstract":"Two-dimensional (2D) transition metal dichalcogenides and their alloys provide a unique platform for exploring interlayer charge transfer in van der Waals heterostructures. These structures are crucial for advancing the next-generation electronic, optoelectronic, and quantum devices. In this study, interlayer charge transfer in heterostructures composed of MoSe2, MoS2, and their alloy, MoSSe, is investigated using transient absorption, Raman, and photoluminescence spectroscopy. The experimental results reveal that electron transfer in the alloy heterostructures, MoSSe/MoS2 and MoSe2/MoSSe, is faster than in the pure MoSe2/MoS2 heterostructure, despite the smaller conduction band offsets of the alloy systems. Raman spectroscopy confirms that alloy layers support phonon modes matching those of the pure layers, aligning with theoretical models of phonon-assisted interlayer charge transfer. Additionally, efficient hole transfer is observed in both alloy heterostructures. The findings suggest transition metal dichalcogenides alloys can be used for engineering heterostructures with desired charge transfer properties. By leveraging compositionally tunable band gaps and optical properties, alloy-based heterostructures offer opportunities for designing tailored materials suitable for diverse applications such as photodetectors, light-emitting devices, and flexible electronics. Moreover, the ultrafast charge transfer observed in these systems provides insights into the fundamental mechanisms governing interlayer interactions in 2D materials.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"15 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junshuai Wang, Bingxin Li, Yipeng An, Guilin Song, Shuaikang Zhang
In this study, we explore the interplay between magnetization compensation temperature (Tcom) and thickness in ferrimagnetic CoGd alloys. Temperature-dependent anomalous Hall effect shows that the thickness of CoGd alloys can cause a 160 K shift in Tcom. Element-mapping image measurements display that the concentration of CoGd alloys remains constant regardless of the thickness, while magnetic property measurements indicate that the saturation magnetization (Ms) decreases as the thickness increases. A microstructure constructed by non-coplanar spin is used to account for the modulation of Tcom and Ms with the thickness. Density functional theory offers a microscopic mechanism where the difference in exchange coupling strength between Gd-Co moments should be responsible for thickness-controlled Tcom. Our findings reveal potential opportunities for the use of RE-TM ferrimagnetic films in the development of energy efficient nonvolatile spintronic devices.
{"title":"Interplay between magnetization compensation temperature and thickness in ferrimagnetic CoGd alloy films","authors":"Junshuai Wang, Bingxin Li, Yipeng An, Guilin Song, Shuaikang Zhang","doi":"10.1063/5.0245463","DOIUrl":"https://doi.org/10.1063/5.0245463","url":null,"abstract":"In this study, we explore the interplay between magnetization compensation temperature (Tcom) and thickness in ferrimagnetic CoGd alloys. Temperature-dependent anomalous Hall effect shows that the thickness of CoGd alloys can cause a 160 K shift in Tcom. Element-mapping image measurements display that the concentration of CoGd alloys remains constant regardless of the thickness, while magnetic property measurements indicate that the saturation magnetization (Ms) decreases as the thickness increases. A microstructure constructed by non-coplanar spin is used to account for the modulation of Tcom and Ms with the thickness. Density functional theory offers a microscopic mechanism where the difference in exchange coupling strength between Gd-Co moments should be responsible for thickness-controlled Tcom. Our findings reveal potential opportunities for the use of RE-TM ferrimagnetic films in the development of energy efficient nonvolatile spintronic devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"24 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Effective manipulation of magnetic beads (MBs) with dimensions similar to single cells is crucial for advancing clinical and diagnostic technologies. Traditional methods like optical tweezers and dielectrophoresis often require complex setups, making them less suitable for scalable laboratory-on-a-chip (LOC) systems. While strain-mediated magnetoelectric (ME) micro-motors offer a promising alternative, they are limited by a 45° rotation when using planar electrode systems, the complexity of multi-electrode systems for rotations beyond 45°, and the lower thermal stability of symmetrical ferromagnetic (FM) rings or disks. This work introduces a ME-based LOC device that incorporates strain-mediated micro-magnetic motors, utilizing shape-anisotropic FM elliptical rings on a ferroelectric substrate to achieve MB rotations up to 90° experimentally with a simple planar electrode system. The inherent high thermal stability of elliptical FM rings enables this rotation without the need for multi-electrode designs. Micromagnetic simulations are employed to identify the optimal elliptical ring structures that generate the localized stray magnetic fields necessary for trapping and rotating MBs. Effective single MB trapping with optimized MB concentrations and flow rates is demonstrated with 40% capture probability. Under an applied electric field of 0.8 MV/m, a 90o rotation is achieved for a 1.5 μm wide elliptical ring, closely aligning with micromagnetic modeling results. The ability to achieve 90° MB rotation without complicated experimental setup opens possibilities for critical biotechnology applications, such as photothermal and hyperthermia therapy, where the thermally stable, highly shape-anisotropic FMs in ME-based LOC devices could be transformative.
{"title":"Voltage-controlled strain-mediated elliptical micro-magnetic motors for single magnetic bead manipulation","authors":"Pankaj Pathak, Vinit Kumar Yadav, Dhiman Mallick","doi":"10.1063/5.0252514","DOIUrl":"https://doi.org/10.1063/5.0252514","url":null,"abstract":"Effective manipulation of magnetic beads (MBs) with dimensions similar to single cells is crucial for advancing clinical and diagnostic technologies. Traditional methods like optical tweezers and dielectrophoresis often require complex setups, making them less suitable for scalable laboratory-on-a-chip (LOC) systems. While strain-mediated magnetoelectric (ME) micro-motors offer a promising alternative, they are limited by a 45° rotation when using planar electrode systems, the complexity of multi-electrode systems for rotations beyond 45°, and the lower thermal stability of symmetrical ferromagnetic (FM) rings or disks. This work introduces a ME-based LOC device that incorporates strain-mediated micro-magnetic motors, utilizing shape-anisotropic FM elliptical rings on a ferroelectric substrate to achieve MB rotations up to 90° experimentally with a simple planar electrode system. The inherent high thermal stability of elliptical FM rings enables this rotation without the need for multi-electrode designs. Micromagnetic simulations are employed to identify the optimal elliptical ring structures that generate the localized stray magnetic fields necessary for trapping and rotating MBs. Effective single MB trapping with optimized MB concentrations and flow rates is demonstrated with 40% capture probability. Under an applied electric field of 0.8 MV/m, a 90o rotation is achieved for a 1.5 μm wide elliptical ring, closely aligning with micromagnetic modeling results. The ability to achieve 90° MB rotation without complicated experimental setup opens possibilities for critical biotechnology applications, such as photothermal and hyperthermia therapy, where the thermally stable, highly shape-anisotropic FMs in ME-based LOC devices could be transformative.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"22 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143443906","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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