Smith–Purcell radiation (SPR) has emerged as a compelling platform for exploring light–matter interactions and realizing tunable free-electron light sources. As the demand for compact, high-performance emitters grows, there is increasing interest in structurally reconfigurable SPR systems that operate in the near-field regime—where enhanced light confinement, subwavelength field shaping, and spatial focusing become accessible. However, conventional SPR designs, which treat gratings as homogeneous and indivisible structures, lack the fine-grained tunability required for coordinated spectral and spatial control and inherently support parasitic surface modes. Here, we fill this key gap by introducing an innovative design paradigm. Specifically, we disassemble traditional grating structures into a programmable array of discrete functional units, simulate the electromagnetic response of each unit via CST particle-in-cell simulations, and ultimately assemble these pre-characterized units into a reconfigurable grating. This design paradigm embeds spectral and spatial control at the unit level, enabling frequency locking through Doppler compensation, energy convergence via directional alignment, and suppression of surface-bound modes by breaking Bloch symmetry. Additionally, this design paradigm allows near-field SPR to achieve coherent and focused emission without reliance on external optics. Furthermore, our grating structure demonstrates robustness against variations in electron velocity and electron position. Our results pave the way for developing on-chip terahertz sources and programmable free-electron-based light sources.
{"title":"Near-field coherent and focused free-electron radiation based on ordered structures with functional units","authors":"Yixin Peng, Ping Zhang, Ziqi Guo, Yitao Li, Hao Li, Hanghui Deng, Sunchao Huang, Shaomeng Wang, Yubin Gong","doi":"10.1063/5.0294015","DOIUrl":"https://doi.org/10.1063/5.0294015","url":null,"abstract":"Smith–Purcell radiation (SPR) has emerged as a compelling platform for exploring light–matter interactions and realizing tunable free-electron light sources. As the demand for compact, high-performance emitters grows, there is increasing interest in structurally reconfigurable SPR systems that operate in the near-field regime—where enhanced light confinement, subwavelength field shaping, and spatial focusing become accessible. However, conventional SPR designs, which treat gratings as homogeneous and indivisible structures, lack the fine-grained tunability required for coordinated spectral and spatial control and inherently support parasitic surface modes. Here, we fill this key gap by introducing an innovative design paradigm. Specifically, we disassemble traditional grating structures into a programmable array of discrete functional units, simulate the electromagnetic response of each unit via CST particle-in-cell simulations, and ultimately assemble these pre-characterized units into a reconfigurable grating. This design paradigm embeds spectral and spatial control at the unit level, enabling frequency locking through Doppler compensation, energy convergence via directional alignment, and suppression of surface-bound modes by breaking Bloch symmetry. Additionally, this design paradigm allows near-field SPR to achieve coherent and focused emission without reliance on external optics. Furthermore, our grating structure demonstrates robustness against variations in electron velocity and electron position. Our results pave the way for developing on-chip terahertz sources and programmable free-electron-based light sources.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"241 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115621","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}
Electronic and structural degrees of freedom are often intimately coupled in strongly correlated systems, which result in intriguing macroscopic and microscopic phenomena. Using the well-studied material VO2 as a prototype, here we explore the domain distribution across the metal–insulator transition (MIT). We use macroscopic as well as microscopic techniques, such as first-order reversal curve (FORC) and infrared imaging, to probe the domain distributions across the MIT. This study compares MIT in thin films of VO2 with different grain sizes grown by pulsed laser deposition and dc sputtering. We explore the relation between the nature of the FORC distribution and the corresponding thermal hysteresis due to interactions between the supercooled metallic domains and surrounding insulating matrix. Our multi-probe study with quantitative analysis provides a correlation between the growth, domain interaction, and domain nucleation process in MIT.
{"title":"Multi-probe detection of domain nucleation across the metal–insulator transition in VO2","authors":"Shubhankar Paul, Giordano Mattoni, Amitava Ghosh, Pooja Kesarwani, Dipak Sahu, Monika Ahlawat, Ashok P, Amit Verma, Vishal Govind Rao, Chanchal Sow","doi":"10.1063/5.0291227","DOIUrl":"https://doi.org/10.1063/5.0291227","url":null,"abstract":"Electronic and structural degrees of freedom are often intimately coupled in strongly correlated systems, which result in intriguing macroscopic and microscopic phenomena. Using the well-studied material VO2 as a prototype, here we explore the domain distribution across the metal–insulator transition (MIT). We use macroscopic as well as microscopic techniques, such as first-order reversal curve (FORC) and infrared imaging, to probe the domain distributions across the MIT. This study compares MIT in thin films of VO2 with different grain sizes grown by pulsed laser deposition and dc sputtering. We explore the relation between the nature of the FORC distribution and the corresponding thermal hysteresis due to interactions between the supercooled metallic domains and surrounding insulating matrix. Our multi-probe study with quantitative analysis provides a correlation between the growth, domain interaction, and domain nucleation process in MIT.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"28 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116142","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}
Karina L. Hudson, Davide Costa, Davide Degli Esposti, Lucas E. A. Stehouwer, Giordano Scappucci
Constricting transport through a one-dimensional quantum point contact in the quantum Hall regime enables gate-tunable selection of the edge modes propagating between voltage probe electrodes. Here, we investigate the quantum Hall effect in a quantum point contact fabricated on low disorder strained germanium quantum wells. For increasing magnetic field, we observe Zeeman spin-split 1D ballistic hole transport evolving to integer quantum Hall states, with well-defined quantized conductance increasing in multiples of e2/h down to the first integer filling factor ν=1. These results establish strained germanium as a viable platform for complex experiments probing many-body states and quantum phase transitions.
{"title":"Conductance plateaus at quantum Hall integer filling factors in germanium quantum point contacts","authors":"Karina L. Hudson, Davide Costa, Davide Degli Esposti, Lucas E. A. Stehouwer, Giordano Scappucci","doi":"10.1063/5.0307573","DOIUrl":"https://doi.org/10.1063/5.0307573","url":null,"abstract":"Constricting transport through a one-dimensional quantum point contact in the quantum Hall regime enables gate-tunable selection of the edge modes propagating between voltage probe electrodes. Here, we investigate the quantum Hall effect in a quantum point contact fabricated on low disorder strained germanium quantum wells. For increasing magnetic field, we observe Zeeman spin-split 1D ballistic hole transport evolving to integer quantum Hall states, with well-defined quantized conductance increasing in multiples of e2/h down to the first integer filling factor ν=1. These results establish strained germanium as a viable platform for complex experiments probing many-body states and quantum phase transitions.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"9 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116212","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}
Boiling of dielectric liquids is limited by a trade-off between efficient nucleation and interfacial instabilities that trigger premature critical heat flux (CHF). In this Letter, we show that the dynamics of bubble coalescence and liquid-film drainage in HFE (Hydrofluoroether)-7100 can be tuned by coupling surface structuring with fluid composition. Micro-grooved surfaces enhance the heat transfer coefficient (HTC) by increasing nucleation-site density, but hydrodynamic instabilities restrict gains in CHF. Introducing a small fraction of high surface-tension lubricant alters interfacial stresses: the oil accumulates at the gas–liquid interface, generates Marangoni convection into thinning films, and suppresses coalescence. This stabilizes bubble dynamics, concentrates energy fluctuations at low frequencies, and delays CHF. When 1 wt. % oil is combined with 100 μm-pitch grooves, HTC is enhanced by 64.9% relative to a flat surface, while CHF is significantly extended. These results highlight the fundamental role of Marangoni-driven interfacial flows in retarding film rupture in boiling and demonstrate a hybrid pathway to overcome the HTC–CHF trade-off in dielectric boiling.
{"title":"Marangoni-stabilized bubble dynamics enable simultaneous HTC enhancement and CHF delay in dielectric boiling","authors":"Yongfang Huang, Donato Fontanarosa, Mulugeta Gebrekiros Berhe, Sylvie Castagne, Xiaoxiao Xu, Maria Rosaria Vetrano","doi":"10.1063/5.0312670","DOIUrl":"https://doi.org/10.1063/5.0312670","url":null,"abstract":"Boiling of dielectric liquids is limited by a trade-off between efficient nucleation and interfacial instabilities that trigger premature critical heat flux (CHF). In this Letter, we show that the dynamics of bubble coalescence and liquid-film drainage in HFE (Hydrofluoroether)-7100 can be tuned by coupling surface structuring with fluid composition. Micro-grooved surfaces enhance the heat transfer coefficient (HTC) by increasing nucleation-site density, but hydrodynamic instabilities restrict gains in CHF. Introducing a small fraction of high surface-tension lubricant alters interfacial stresses: the oil accumulates at the gas–liquid interface, generates Marangoni convection into thinning films, and suppresses coalescence. This stabilizes bubble dynamics, concentrates energy fluctuations at low frequencies, and delays CHF. When 1 wt. % oil is combined with 100 μm-pitch grooves, HTC is enhanced by 64.9% relative to a flat surface, while CHF is significantly extended. These results highlight the fundamental role of Marangoni-driven interfacial flows in retarding film rupture in boiling and demonstrate a hybrid pathway to overcome the HTC–CHF trade-off in dielectric boiling.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115614","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}
Aakash Singh, Brindaban Modak, Santosh K. Gupta, K. Sudarshan, Sai Santosh Kumar Raavi
Strategic doping in halide double perovskites, with structure A2M(I)M′(III)X6, has shown great potential in improving their emission properties. While the site preference of monovalent or trivalent metal dopants is on the expected lines, the same is not true for bivalent dopants, like Mn2+, etc. In this Letter, we employ positron annihilation lifetime spectroscopy measurements along with density functional theory (DFT) calculations to address the preferred doping site of Mn2+ in the Cs2AgInCl6 double perovskite structure. Our results conclusively reveal that the preferred substitution site of Mn2+ is Ag+ for the most stable configuration, and the overall decrease in the average lifetime of the positrons indicates an excess of electrons after doping. Furthermore, temperature-dependent photoluminescence measurements reveal a negative thermal quenching of the Mn2+ emission, attributed to effective energy transfer from self-trapped excitons to Mn2+, explained using a two-term Arrhenius equation. Such efficient exciton-dopant energy transfer is crucial, as it bridges the host excitonic states with dopant emission, thereby maximizing luminescence efficiency.
{"title":"Synergetic impact of energy transfer and site preference for enhanced emission in Mn-doped Cs2AgInCl6 double perovskite","authors":"Aakash Singh, Brindaban Modak, Santosh K. Gupta, K. Sudarshan, Sai Santosh Kumar Raavi","doi":"10.1063/5.0301499","DOIUrl":"https://doi.org/10.1063/5.0301499","url":null,"abstract":"Strategic doping in halide double perovskites, with structure A2M(I)M′(III)X6, has shown great potential in improving their emission properties. While the site preference of monovalent or trivalent metal dopants is on the expected lines, the same is not true for bivalent dopants, like Mn2+, etc. In this Letter, we employ positron annihilation lifetime spectroscopy measurements along with density functional theory (DFT) calculations to address the preferred doping site of Mn2+ in the Cs2AgInCl6 double perovskite structure. Our results conclusively reveal that the preferred substitution site of Mn2+ is Ag+ for the most stable configuration, and the overall decrease in the average lifetime of the positrons indicates an excess of electrons after doping. Furthermore, temperature-dependent photoluminescence measurements reveal a negative thermal quenching of the Mn2+ emission, attributed to effective energy transfer from self-trapped excitons to Mn2+, explained using a two-term Arrhenius equation. Such efficient exciton-dopant energy transfer is crucial, as it bridges the host excitonic states with dopant emission, thereby maximizing luminescence efficiency.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115619","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}
Van der Waals heterostructures combining graphene with transition metal dichalcogenides (TMDs) provide a versatile platform for optoelectronic and spintronic devices [Georgiou et al., Nat. Nanotechnol. 8, 100 (2013); Britnell et al., Science 340, 1311 (2013); Roy et al., Nat. Nanotechnol. 8, 826 (2013); Novoselov et al., Science 353, aac9439 (2016); and Safeer et al., Nano Lett. 19, 1074 (2019)]. However, the absence of intrinsic ferroelectricity in most TMDs has limited their application in nonvolatile memory and neuromorphic electronics. Here, we show that R-stacked bilayer WSe2 can serve as a ferroelectric dielectric directly coupled with mono- or bilayer graphene, realizing ferroelectric field-effect transistors with nonvolatile, polarization-controlled modulation of carrier density. The devices exhibit endurance exceeding 108 cycles and retention longer than 8000 s, demonstrating robust and fatigue-free ferroelectric switching. Interfacial charge transfer between WSe2 and graphene is found to play a crucial role in determining the hysteresis width. Moreover, Shubnikov–de Haas oscillations reveal clear signatures of band splitting arising from interfacial spin–orbit interactions. Our results establish a synthetic platform that combines ferroelectricity with spin–orbit proximity, opening opportunities for multifunctional devices based on two-dimensional heterostructures.
结合石墨烯和过渡金属二硫族化合物（TMDs）的范德华异质结构为光电和自旋电子器件提供了一个多功能平台[Georgiou等人，Nat. nanotechnology . 8,100 (2013)；Britnell et al., Science 340, 1311 (2013)；Roy et al., Nat. nanotechnology . 8, 826 (2013)；Novoselov et al., Science 353, aac9439 (2016)；和Safeer等，纳米材料，19 (2019)[j]。然而，大多数tmd缺乏铁电性，限制了它们在非易失性存储器和神经形态电子学中的应用。在这里，我们证明了r堆叠的双层WSe2可以作为铁电介质直接与单层或双层石墨烯耦合，实现具有非易失性，极化控制载流子密度调制的铁电场效应晶体管。该器件的耐用性超过108次循环，保持时间超过8000秒，显示出稳健和无疲劳的铁电开关。发现WSe2和石墨烯之间的界面电荷转移在决定滞后宽度方面起着至关重要的作用。此外，Shubnikov-de Haas振荡揭示了界面自旋轨道相互作用引起的能带分裂的清晰特征。我们的研究结果建立了一个结合铁电性和自旋轨道接近性的合成平台，为基于二维异质结构的多功能器件开辟了机会。
{"title":"Integrated ferroelectricity and spin–orbit proximity in R-stacked bilayer WSe2/graphene heterostructures","authors":"Gengxuan Wang, Shengsheng Lin, Yuhao Li, Yuanhao Wei, Jiarui Wang, Takashi Taniguchi, Kenji Watanabe, Songlin Li, Yi Shi, Zaiyao Fei","doi":"10.1063/5.0312034","DOIUrl":"https://doi.org/10.1063/5.0312034","url":null,"abstract":"Van der Waals heterostructures combining graphene with transition metal dichalcogenides (TMDs) provide a versatile platform for optoelectronic and spintronic devices [Georgiou et al., Nat. Nanotechnol. 8, 100 (2013); Britnell et al., Science 340, 1311 (2013); Roy et al., Nat. Nanotechnol. 8, 826 (2013); Novoselov et al., Science 353, aac9439 (2016); and Safeer et al., Nano Lett. 19, 1074 (2019)]. However, the absence of intrinsic ferroelectricity in most TMDs has limited their application in nonvolatile memory and neuromorphic electronics. Here, we show that R-stacked bilayer WSe2 can serve as a ferroelectric dielectric directly coupled with mono- or bilayer graphene, realizing ferroelectric field-effect transistors with nonvolatile, polarization-controlled modulation of carrier density. The devices exhibit endurance exceeding 108 cycles and retention longer than 8000 s, demonstrating robust and fatigue-free ferroelectric switching. Interfacial charge transfer between WSe2 and graphene is found to play a crucial role in determining the hysteresis width. Moreover, Shubnikov–de Haas oscillations reveal clear signatures of band splitting arising from interfacial spin–orbit interactions. Our results establish a synthetic platform that combines ferroelectricity with spin–orbit proximity, opening opportunities for multifunctional devices based on two-dimensional heterostructures.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"15 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115623","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}
A. Khanolkar, S. Adnan, M. Minaruzzaman, L. Malakkal, D. B. Thomson, D. B. Turner, J. M. Mann, D. H. Hurley, M. Khafizov
We investigate the temperature dependence of the frequency and linewidth of the triply degenerate T2g zone-centered optical phonon in flux-grown ceria and hydrothermally synthesized thoria single crystals from room temperature to 1273 K using Raman spectroscopy. Both crystals exhibit an expected increase in the phonon linewidth with temperature due to enhanced phonon–phonon scattering. However, ceria displays an anomalous linewidth reduction in the temperature range of 1023–1123 K. First-principles phonon linewidth calculations considering cubic and quartic phonon interactions within temperature-independent phonon dispersion fail to describe this anomaly. A parameterization of the temperature-dependent second-order interatomic force constants based on previously reported phonon dispersion measured at room and high temperatures predicts a deviation from the monotonic linewidth increase, albeit at temperatures lower than those observed experimentally for ceria. The qualitative agreement in the trend of temperature-dependent linewidth suggests that lattice anharmonicity-induced phonon renormalization plays a role in phonon lifetime. Specifically, a change in the overlap between softened acoustic and optical branches in the dispersion curve reduces the available phonon scattering phase space of the Raman-active mode at the zone center, leading to an increased phonon lifetime within a narrow temperature interval. These findings provide insights into higher-order anharmonic interactions in ceria and thoria, motivating further investigations into the role of anharmonicity-induced phonon renormalization on phonon lifetimes at high temperatures.
{"title":"Lattice anharmonicity effects in fluorite oxide single crystals and anomalous increase in phonon lifetime in ceria at elevated temperature","authors":"A. Khanolkar, S. Adnan, M. Minaruzzaman, L. Malakkal, D. B. Thomson, D. B. Turner, J. M. Mann, D. H. Hurley, M. Khafizov","doi":"10.1063/5.0297396","DOIUrl":"https://doi.org/10.1063/5.0297396","url":null,"abstract":"We investigate the temperature dependence of the frequency and linewidth of the triply degenerate T2g zone-centered optical phonon in flux-grown ceria and hydrothermally synthesized thoria single crystals from room temperature to 1273 K using Raman spectroscopy. Both crystals exhibit an expected increase in the phonon linewidth with temperature due to enhanced phonon–phonon scattering. However, ceria displays an anomalous linewidth reduction in the temperature range of 1023–1123 K. First-principles phonon linewidth calculations considering cubic and quartic phonon interactions within temperature-independent phonon dispersion fail to describe this anomaly. A parameterization of the temperature-dependent second-order interatomic force constants based on previously reported phonon dispersion measured at room and high temperatures predicts a deviation from the monotonic linewidth increase, albeit at temperatures lower than those observed experimentally for ceria. The qualitative agreement in the trend of temperature-dependent linewidth suggests that lattice anharmonicity-induced phonon renormalization plays a role in phonon lifetime. Specifically, a change in the overlap between softened acoustic and optical branches in the dispersion curve reduces the available phonon scattering phase space of the Raman-active mode at the zone center, leading to an increased phonon lifetime within a narrow temperature interval. These findings provide insights into higher-order anharmonic interactions in ceria and thoria, motivating further investigations into the role of anharmonicity-induced phonon renormalization on phonon lifetimes at high temperatures.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"34 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115624","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}
Felix Hahne, Teresa Klara Pfau, Liza Žaper, Lucio Stefan, Thibault Capelle, Andrea Ranfagni, Martino Poggio, Albert Schliesser
Hybrid systems composed of a single nitrogen-vacancy center spin magnetically coupled to a macroscopic mechanical resonator constitute promising platforms for the realization of quantum information protocols and for quantum sensing applications. The magnetic structure that mediates the interaction must ensure high field gradients while preserving the spin and mechanical properties. We present a spin-mechanical setup built around a cobalt nanomagnet grown with focused electron beam-induced deposition. The magnetic structure is fully characterized, and a maximum gradient of 170 kT m-1 is directly measured at a spin-oscillator distance of a few hundred nanometers. Spin coherence was preserved at the value of 20μs up to a gradient of 25 kT m-1. The effect of the mechanical motion on the spin dynamics was observed, thus signifying the presence of spin-mechanics coupling. Given the noninvasive nature of the nanomagnet deposition process, we foresee the adoption of such structures in hybrid platforms with high-quality factor resonators, in the “magnet on oscillator” configuration.
{"title":"Measuring high field gradients of cobalt nanomagnets in a spin-mechanical setup","authors":"Felix Hahne, Teresa Klara Pfau, Liza Žaper, Lucio Stefan, Thibault Capelle, Andrea Ranfagni, Martino Poggio, Albert Schliesser","doi":"10.1063/5.0301921","DOIUrl":"https://doi.org/10.1063/5.0301921","url":null,"abstract":"Hybrid systems composed of a single nitrogen-vacancy center spin magnetically coupled to a macroscopic mechanical resonator constitute promising platforms for the realization of quantum information protocols and for quantum sensing applications. The magnetic structure that mediates the interaction must ensure high field gradients while preserving the spin and mechanical properties. We present a spin-mechanical setup built around a cobalt nanomagnet grown with focused electron beam-induced deposition. The magnetic structure is fully characterized, and a maximum gradient of 170 kT m-1 is directly measured at a spin-oscillator distance of a few hundred nanometers. Spin coherence was preserved at the value of 20μs up to a gradient of 25 kT m-1. The effect of the mechanical motion on the spin dynamics was observed, thus signifying the presence of spin-mechanics coupling. Given the noninvasive nature of the nanomagnet deposition process, we foresee the adoption of such structures in hybrid platforms with high-quality factor resonators, in the “magnet on oscillator” configuration.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"92 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115680","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}
Antiferromagnetic kagome metal FeGe has attracted tremendous attention in condensed matter physics due to the charge density wave (CDW) being well below its magnetic transition temperature. Up to now, numerous works on kagome FeGe have been based on single crystal bulk, but its thin film form has still not been reported. Here, we achieved epitaxial growth of FeGe thin films on Al2O3 substrates using molecular beam epitaxy. Structural characterization with x-ray diffraction, atomic force microscopy, and high-resolution scanning transmission electron microscopy reveals single phase with flat surface of kagome FeGe thin films. Moreover, a Néel temperature of 397 K and a rapid variation of Hall coefficient and magnetoresistance around 100 K, which might be related to the CDW, were revealed via transport measurements. The high quality kagome FeGe thin films are expected to provide a versatile platform to study the mechanism of CDW and explore the application of FeGe in antiferromagnetic spintronics.
{"title":"Epitaxial growth and magneto-transport properties of kagome metal FeGe thin films","authors":"Xiaoyue Song, Yanshen Chen, Yongcheng Deng, Tongao Sun, Fei Wang, Guodong Wei, Xionghua Liu, Kaiyou Wang","doi":"10.1063/5.0310077","DOIUrl":"https://doi.org/10.1063/5.0310077","url":null,"abstract":"Antiferromagnetic kagome metal FeGe has attracted tremendous attention in condensed matter physics due to the charge density wave (CDW) being well below its magnetic transition temperature. Up to now, numerous works on kagome FeGe have been based on single crystal bulk, but its thin film form has still not been reported. Here, we achieved epitaxial growth of FeGe thin films on Al2O3 substrates using molecular beam epitaxy. Structural characterization with x-ray diffraction, atomic force microscopy, and high-resolution scanning transmission electron microscopy reveals single phase with flat surface of kagome FeGe thin films. Moreover, a Néel temperature of 397 K and a rapid variation of Hall coefficient and magnetoresistance around 100 K, which might be related to the CDW, were revealed via transport measurements. The high quality kagome FeGe thin films are expected to provide a versatile platform to study the mechanism of CDW and explore the application of FeGe in antiferromagnetic spintronics.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"241 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115568","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}
Song Hao, Wenjie Xu, Xiangyu Xing, Mingrui Zhou, Jiahao Wu, Changhao Ji, Buwei Wang, Tao Xu, Bin Cheng, Shi-Jun Liang
Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have emerged as promising semiconductors beyond the limits of conventional scaling. Yet, wafer-scale synthesis remains hindered by the pervasive generation of atomic defects that degrade electronic applications. Here, we develop a eutectic-vapor growth strategy that enables direct synthesis of highly crystalline 2D MoS2 at unexpectedly low temperatures. This method simultaneously avoids incomplete precursor reaction and the defect-promoting conditions inherent to high-temperature growth. First-principles calculations combined with ab initio molecular dynamics reveal that Mo–S precursors undergo a eutectic interaction with halide salts, producing volatile molecular growth species at reduced temperatures. Potassium ions adsorbed at the MoS2 edge substantially lower the incorporation barrier of reactive growth units, which is expected to reduce the propensity for defect formation during crystal growth. This eutectic-mediated growth mechanism provides a chemically grounded and broadly applicable route for low-temperature synthesis of 2D TMDCs with substantially reduced defect densities.
{"title":"Eutectic-vapor-driven low-temperature growth of high-crystallinity two-dimensional TMDCs","authors":"Song Hao, Wenjie Xu, Xiangyu Xing, Mingrui Zhou, Jiahao Wu, Changhao Ji, Buwei Wang, Tao Xu, Bin Cheng, Shi-Jun Liang","doi":"10.1063/5.0313009","DOIUrl":"https://doi.org/10.1063/5.0313009","url":null,"abstract":"Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have emerged as promising semiconductors beyond the limits of conventional scaling. Yet, wafer-scale synthesis remains hindered by the pervasive generation of atomic defects that degrade electronic applications. Here, we develop a eutectic-vapor growth strategy that enables direct synthesis of highly crystalline 2D MoS2 at unexpectedly low temperatures. This method simultaneously avoids incomplete precursor reaction and the defect-promoting conditions inherent to high-temperature growth. First-principles calculations combined with ab initio molecular dynamics reveal that Mo–S precursors undergo a eutectic interaction with halide salts, producing volatile molecular growth species at reduced temperatures. Potassium ions adsorbed at the MoS2 edge substantially lower the incorporation barrier of reactive growth units, which is expected to reduce the propensity for defect formation during crystal growth. This eutectic-mediated growth mechanism provides a chemically grounded and broadly applicable route for low-temperature synthesis of 2D TMDCs with substantially reduced defect densities.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"20 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2026-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146115569","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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