Hiroto Yokoyama, Takahiro Umemoto, Akiko Kumada, Masahiro Sato
Accurately predicting the properties of polymers is essential for data-driven materials design. However, such predictions are often challenged by the limited availability of polymer-related data and the fact that high-performance polymers of interest typically lie outside the distribution of existing datasets. In this study, we develop a machine learning model that enhances extrapolative prediction accuracy beyond the training data by leveraging hierarchical, physics-informed descriptors. Specifically, we utilize quantum mechanical (QM) descriptors derived from density functional theory calculations, molecular dynamics (MD) descriptors representing structural and dynamical properties, and force field (FF) descriptors characterizing the interaction parameters used in MD simulations. We investigated two types of extrapolation tasks: extrapolation beyond the range of physical properties and extrapolation to structurally dissimilar molecules. By systematically evaluating all non-zero combinations of QM, MD, and FF descriptors, we find that selected subsets often outperform models using the full descriptor set. This highlights the critical role of dimensionality reduction and descriptor relevance, especially under data-scarce conditions. Comparisons with structure-based models employing molecular fingerprints or molecular graphs further demonstrated the superiority of the proposed model based on selected physics-based descriptors.
{"title":"Extrapolative prediction of polymer properties using physics-informed hierarchical descriptors","authors":"Hiroto Yokoyama, Takahiro Umemoto, Akiko Kumada, Masahiro Sato","doi":"10.1063/5.0292279","DOIUrl":"https://doi.org/10.1063/5.0292279","url":null,"abstract":"Accurately predicting the properties of polymers is essential for data-driven materials design. However, such predictions are often challenged by the limited availability of polymer-related data and the fact that high-performance polymers of interest typically lie outside the distribution of existing datasets. In this study, we develop a machine learning model that enhances extrapolative prediction accuracy beyond the training data by leveraging hierarchical, physics-informed descriptors. Specifically, we utilize quantum mechanical (QM) descriptors derived from density functional theory calculations, molecular dynamics (MD) descriptors representing structural and dynamical properties, and force field (FF) descriptors characterizing the interaction parameters used in MD simulations. We investigated two types of extrapolation tasks: extrapolation beyond the range of physical properties and extrapolation to structurally dissimilar molecules. By systematically evaluating all non-zero combinations of QM, MD, and FF descriptors, we find that selected subsets often outperform models using the full descriptor set. This highlights the critical role of dimensionality reduction and descriptor relevance, especially under data-scarce conditions. Comparisons with structure-based models employing molecular fingerprints or molecular graphs further demonstrated the superiority of the proposed model based on selected physics-based descriptors.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"19 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729100","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}
M. A. Castellanos-Beltran, A. J. Sirois, D. I. Olaya, J. Biesecker, S. P. Benz, P. F. Hopkins
We present experimental measurements and analysis of leakage errors occurring during resonant digital control of a superconducting qubit. By increasing the amplitude of the digital pulse trains and therefore decreasing the duration of the control gates, from 100 to 40 ns for a π-gate, the leakage error rate measured per Clifford gate in a randomized benchmarking test increases from 4.3×10−4 to 2.4×10−3 and becomes the dominant source of single-qubit gate errors for our qubit; these error rates are 1–2 orders of magnitude larger than we measure when controlling the same qubit using traditional, shaped-analog signals. Simulations show the dominant leakage mechanism arises from the increased spectral power of the pulse trains at the frequency ω12 corresponding to excitations from the first excited state |1⟩ to the second excited state |2⟩. Our measurements demonstrate the fundamental limits to resonant digital control of low-anharmonicity qubits and outline the trade-off between reducing gate times while preserving gate fidelity. We discuss possible strategies for mitigating this issue in future digital control implementations.
{"title":"Characterization of leakage errors in a transmon qubit due to resonant digital control","authors":"M. A. Castellanos-Beltran, A. J. Sirois, D. I. Olaya, J. Biesecker, S. P. Benz, P. F. Hopkins","doi":"10.1063/5.0304764","DOIUrl":"https://doi.org/10.1063/5.0304764","url":null,"abstract":"We present experimental measurements and analysis of leakage errors occurring during resonant digital control of a superconducting qubit. By increasing the amplitude of the digital pulse trains and therefore decreasing the duration of the control gates, from 100 to 40 ns for a π-gate, the leakage error rate measured per Clifford gate in a randomized benchmarking test increases from 4.3×10−4 to 2.4×10−3 and becomes the dominant source of single-qubit gate errors for our qubit; these error rates are 1–2 orders of magnitude larger than we measure when controlling the same qubit using traditional, shaped-analog signals. Simulations show the dominant leakage mechanism arises from the increased spectral power of the pulse trains at the frequency ω12 corresponding to excitations from the first excited state |1⟩ to the second excited state |2⟩. Our measurements demonstrate the fundamental limits to resonant digital control of low-anharmonicity qubits and outline the trade-off between reducing gate times while preserving gate fidelity. We discuss possible strategies for mitigating this issue in future digital control implementations.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"93 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729105","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}
The boiling behavior of impacting droplets plays a critical role in spray cooling, directly governing the overall cooling efficiency. Among the various boiling regimes, transitional boiling is particularly significant, as it marks the onset of droplet instability. However, the dynamic interplay between transitional boiling and Leidenfrost rebound remains largely underexplored. In this Letter, we report a universal spontaneous Leidenfrost transitioning (SLT) phenomenon that reveals the coupled evolution of bubble-vapor dynamics, extending the current understanding. Using a custom-designed experimental setup featuring a transparent nano-film heater, we observe that droplets in the SLT regime initially experience vigorous contact boiling following the emergence of a distinctive fingering-crown structure. This stage is followed by repeated contact-levitation cycles, ultimately concluding in Leidenfrost rebound. To explain the formation of the fingering-crown structure, we propose a theoretical model in which a spatial vapor pressure gradient (Δpv) beneath the droplet, which is induced by a hyperbolic vertical vapor velocity distribution, acts as the key mechanism. This model is validated experimentally through combined hydrodynamic (ridge height and dynamic droplet radii) and thermodynamic (heat transfer evolution) analysis. Specifically, our results reveal a characteristic rise-fall pattern between the maximum Δpv and the initial surface temperature, spanning from nucleate boiling to stable Leidenfrost rebound. This trend shows a strong consistency with the predictions of the proposed theoretical model.
{"title":"A spontaneous Leidenfrost transitioning phenomenon","authors":"H. Yang, T. M. Thomas, P. Valluri, K. Sefiane","doi":"10.1063/5.0293908","DOIUrl":"https://doi.org/10.1063/5.0293908","url":null,"abstract":"The boiling behavior of impacting droplets plays a critical role in spray cooling, directly governing the overall cooling efficiency. Among the various boiling regimes, transitional boiling is particularly significant, as it marks the onset of droplet instability. However, the dynamic interplay between transitional boiling and Leidenfrost rebound remains largely underexplored. In this Letter, we report a universal spontaneous Leidenfrost transitioning (SLT) phenomenon that reveals the coupled evolution of bubble-vapor dynamics, extending the current understanding. Using a custom-designed experimental setup featuring a transparent nano-film heater, we observe that droplets in the SLT regime initially experience vigorous contact boiling following the emergence of a distinctive fingering-crown structure. This stage is followed by repeated contact-levitation cycles, ultimately concluding in Leidenfrost rebound. To explain the formation of the fingering-crown structure, we propose a theoretical model in which a spatial vapor pressure gradient (Δpv) beneath the droplet, which is induced by a hyperbolic vertical vapor velocity distribution, acts as the key mechanism. This model is validated experimentally through combined hydrodynamic (ridge height and dynamic droplet radii) and thermodynamic (heat transfer evolution) analysis. Specifically, our results reveal a characteristic rise-fall pattern between the maximum Δpv and the initial surface temperature, spanning from nucleate boiling to stable Leidenfrost rebound. This trend shows a strong consistency with the predictions of the proposed theoretical model.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"53 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729113","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}
Bingcheng Da, Dinusha Herath Mudiyanselage, Dawei Wang, Junzhe Xie, Xianzhi Wei, Houqiang Fu
This work reports the demonstration of ultrawide bandgap (UWBG) semiconductor AlN trench metal-semiconductor field-effect transistors, where the impact of oxygen thermal annealing treatment on device electrical properties was comprehensively studied. The gate trench regions were characterized by x-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). XPS results indicated increased Al–O bonding and stronger formation of AlON layer at the surface, while AFM results showed smoother surface morphology after the treatment. Electrical measurements suggested an increase in the Schottky barrier height under the gate and suppressed fast interface trap states after the treatment. Compared with the device without the treatment, the device with the treatment exhibited more than 22 times improvement in on/off ratio and nearly three times enhancement in breakdown voltage due to reduced leakage and improved interface. Temperature-dependent electrical and interface trap characteristics were also measured and compared. This work can serve as an important reference for the development of UWBG AlN transistors for future high-voltage high-temperature electronics.
{"title":"Effects of oxygen thermal annealing on AlN trench metal-semiconductor field-effect transistors (MESFETs) on single-crystal AlN substrates","authors":"Bingcheng Da, Dinusha Herath Mudiyanselage, Dawei Wang, Junzhe Xie, Xianzhi Wei, Houqiang Fu","doi":"10.1063/5.0304969","DOIUrl":"https://doi.org/10.1063/5.0304969","url":null,"abstract":"This work reports the demonstration of ultrawide bandgap (UWBG) semiconductor AlN trench metal-semiconductor field-effect transistors, where the impact of oxygen thermal annealing treatment on device electrical properties was comprehensively studied. The gate trench regions were characterized by x-ray photoelectron spectroscopy (XPS) and atomic force microscope (AFM). XPS results indicated increased Al–O bonding and stronger formation of AlON layer at the surface, while AFM results showed smoother surface morphology after the treatment. Electrical measurements suggested an increase in the Schottky barrier height under the gate and suppressed fast interface trap states after the treatment. Compared with the device without the treatment, the device with the treatment exhibited more than 22 times improvement in on/off ratio and nearly three times enhancement in breakdown voltage due to reduced leakage and improved interface. Temperature-dependent electrical and interface trap characteristics were also measured and compared. This work can serve as an important reference for the development of UWBG AlN transistors for future high-voltage high-temperature electronics.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"8 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729109","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}
Alexey A. Sokolik, Azat F. Aminov, Evgenii E. Vdovin, Yurii N. Khanin, Mikhail A. Kashchenko, Denis A. Bandurin, Davit A. Ghazaryan, Sergey V. Morozov, Kostya S. Novoselov
Tunneling conductance between two bilayer graphene (BLG) sheets separated by 2 nm-thick insulating barrier was measured in two devices with the twist angles between BLGs less than 1°. At small bias voltages, tunneling occurs with conservation of energy and momentum at the points of intersection between two relatively shifted Fermi circles. Here, we experimentally found and theoretically described signatures of electron–hole asymmetric band structure of BLG: since holes are heavier, the tunneling conductance is enhanced at the hole doping due to the higher density of states. Another key feature of BLG that we explore is gap opening in a vertical electric field with a strong polarization of electron wave function at van Hove singularities near the gap edges. This polarization, by shifting electron wave function in one BLG closer to or father from the other BLG, gives rise to asymmetric tunneling resonances in the conductance around charge neutrality points, which result in strong sensitivity of the tunneling current to minor changes of the gate voltages. The observed phenomena are reproduced by our theoretical model taking into account electrostatics of the dual-gated structure, quantum capacitance effects, and self-consistent gap openings in both BLGs.
{"title":"Probing the features of electron dispersion by tunneling between slightly twisted bilayer graphene sheets","authors":"Alexey A. Sokolik, Azat F. Aminov, Evgenii E. Vdovin, Yurii N. Khanin, Mikhail A. Kashchenko, Denis A. Bandurin, Davit A. Ghazaryan, Sergey V. Morozov, Kostya S. Novoselov","doi":"10.1063/5.0303858","DOIUrl":"https://doi.org/10.1063/5.0303858","url":null,"abstract":"Tunneling conductance between two bilayer graphene (BLG) sheets separated by 2 nm-thick insulating barrier was measured in two devices with the twist angles between BLGs less than 1°. At small bias voltages, tunneling occurs with conservation of energy and momentum at the points of intersection between two relatively shifted Fermi circles. Here, we experimentally found and theoretically described signatures of electron–hole asymmetric band structure of BLG: since holes are heavier, the tunneling conductance is enhanced at the hole doping due to the higher density of states. Another key feature of BLG that we explore is gap opening in a vertical electric field with a strong polarization of electron wave function at van Hove singularities near the gap edges. This polarization, by shifting electron wave function in one BLG closer to or father from the other BLG, gives rise to asymmetric tunneling resonances in the conductance around charge neutrality points, which result in strong sensitivity of the tunneling current to minor changes of the gate voltages. The observed phenomena are reproduced by our theoretical model taking into account electrostatics of the dual-gated structure, quantum capacitance effects, and self-consistent gap openings in both BLGs.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"29 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729111","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}
Daniel Brito, James Caleb Peters, Francis Leonard Deepak, Sascha Sadewasser, Francisco Rivadulla, Marcel S. Claro
The increase in thermal conductivity, κ, at small period lengths in covalently bonded semiconductor and oxide epitaxial superlattices (SLs) is a hallmark of coherent phonon transport and a route for improving heat dissipation in the thin limit. Here, we show that, on the contrary, the phonon coherence length remains shorter than the minimum SL period in van der Waals (vdW) SLs. We measured the cross-plane κz of epitaxial Bi2Se3/β-In2Se3 vdW SLs grown by molecular beam epitaxy; our results show that κ decreases monotonically with increasing interface density down to the two-layer period limit. This suggests that the weak interface vdW bonding of these SLs results in diffusive phonon transport over the whole period range. We discuss further reduction to single-layer SLs and its effects on crystal and interface quality. The results presented in this paper highlight a constraint for thermal management in vdW-based nanoelectronic and thermoelectric devices.
{"title":"Incoherent phonon transport dominates the out-of-plane thermal conductivity of epitaxial van der Waals Bi2Se3/In2Se3 superlattices","authors":"Daniel Brito, James Caleb Peters, Francis Leonard Deepak, Sascha Sadewasser, Francisco Rivadulla, Marcel S. Claro","doi":"10.1063/5.0304515","DOIUrl":"https://doi.org/10.1063/5.0304515","url":null,"abstract":"The increase in thermal conductivity, κ, at small period lengths in covalently bonded semiconductor and oxide epitaxial superlattices (SLs) is a hallmark of coherent phonon transport and a route for improving heat dissipation in the thin limit. Here, we show that, on the contrary, the phonon coherence length remains shorter than the minimum SL period in van der Waals (vdW) SLs. We measured the cross-plane κz of epitaxial Bi2Se3/β-In2Se3 vdW SLs grown by molecular beam epitaxy; our results show that κ decreases monotonically with increasing interface density down to the two-layer period limit. This suggests that the weak interface vdW bonding of these SLs results in diffusive phonon transport over the whole period range. We discuss further reduction to single-layer SLs and its effects on crystal and interface quality. The results presented in this paper highlight a constraint for thermal management in vdW-based nanoelectronic and thermoelectric devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"31 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729187","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}
Time-resolved estimation of viscoelastic properties is essential for capturing dynamic mechanical changes in soft materials and biological tissues. Viscoelastic parameters can be estimated from shear-wave velocity (SWV) dispersion, but repeated excitations at different frequencies limit temporal resolution. We introduce a method of SWV dispersion measurement using a shear-wave multi-frequency pulse (SW-MFP) that encodes several chosen frequencies into a single excitation. Shear elasticity and viscosity estimates are obtained by fitting the measured SWV dispersion to the Kelvin–Voigt model. Experiments were performed using a compact setup with dual plane wave ultrasound transducers and a miniaturized SW actuator. Tissue-mimicking phantoms with varied viscoelastic properties were distinguished by their SWV dispersion curves and corresponding viscoelastic parameter estimates. These results demonstrate SW-MFP for single-shot viscoelastic sensing, providing a pathway toward real-time viscoelastic characterization of dynamic soft materials in biomedical and industrial applications.
{"title":"Shear-wave multi-frequency pulse for single-shot viscoelastic sensing","authors":"Shane Steinberg, Yuu Ono, Sreeraman Rajan","doi":"10.1063/5.0299198","DOIUrl":"https://doi.org/10.1063/5.0299198","url":null,"abstract":"Time-resolved estimation of viscoelastic properties is essential for capturing dynamic mechanical changes in soft materials and biological tissues. Viscoelastic parameters can be estimated from shear-wave velocity (SWV) dispersion, but repeated excitations at different frequencies limit temporal resolution. We introduce a method of SWV dispersion measurement using a shear-wave multi-frequency pulse (SW-MFP) that encodes several chosen frequencies into a single excitation. Shear elasticity and viscosity estimates are obtained by fitting the measured SWV dispersion to the Kelvin–Voigt model. Experiments were performed using a compact setup with dual plane wave ultrasound transducers and a miniaturized SW actuator. Tissue-mimicking phantoms with varied viscoelastic properties were distinguished by their SWV dispersion curves and corresponding viscoelastic parameter estimates. These results demonstrate SW-MFP for single-shot viscoelastic sensing, providing a pathway toward real-time viscoelastic characterization of dynamic soft materials in biomedical and industrial applications.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"44 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729110","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}
Zhili Xu, Peng Kong, Linqing Ye, Jianzhi Deng, Bing Tang, Rengui Bi, Chao Yang
The significantly enhanced superconducting transition temperature (Tc) observed at the FeSe/SrTiO3 (FeSe/STO) interface has garnered substantial attention over the past decade. Numerous experiments have demonstrated that the complex TiOx-terminated STO interface structure plays a crucial role in mediating superconductivity. In this work, using first-principles calculations, we find that the magnetic ground state of the interface structures exhibits two distinct evolutionary trends: it shifts from paramagnetic (PM) to an (anti-)ferromagnetic state in the presence of Sr defects or charge doping, and transitions to a ferromagnetic state when the substrate thickness is less than five atomic layers. Calculated spin charge density differences reveal that the polarized spins are primarily distributed around the interface region. As the thickness of the STO substrate increases, electrons transfer from the interface to the substrate—this leads to a reduction in the polarized spin density near the interface and ultimately drives a transition to the PM phase. Our results reveal that the magnetic moments of Fe atoms in FeSe/STO with a TiOx interface structure increase with increasing atomic layer thickness, whereas those in FeSe/STO without a TiOx interface structure exhibit the opposite trend (i.e., decreasing). In addition, compared with the previously reported band structure, the additional Ti-derived bands crossing the Fermi energy are absent. More importantly, we can observe the replica band near the M point, which is in agreement with previously reported results. Our results indicate that the magnetic properties of the FeSe/STO interface are critical to achieving high-temperature superconductivity.
{"title":"Magnetic phase transitions in Sr-defective monolayer FeSe/SrTiO3 interfaces: A first-principles study","authors":"Zhili Xu, Peng Kong, Linqing Ye, Jianzhi Deng, Bing Tang, Rengui Bi, Chao Yang","doi":"10.1063/5.0304420","DOIUrl":"https://doi.org/10.1063/5.0304420","url":null,"abstract":"The significantly enhanced superconducting transition temperature (Tc) observed at the FeSe/SrTiO3 (FeSe/STO) interface has garnered substantial attention over the past decade. Numerous experiments have demonstrated that the complex TiOx-terminated STO interface structure plays a crucial role in mediating superconductivity. In this work, using first-principles calculations, we find that the magnetic ground state of the interface structures exhibits two distinct evolutionary trends: it shifts from paramagnetic (PM) to an (anti-)ferromagnetic state in the presence of Sr defects or charge doping, and transitions to a ferromagnetic state when the substrate thickness is less than five atomic layers. Calculated spin charge density differences reveal that the polarized spins are primarily distributed around the interface region. As the thickness of the STO substrate increases, electrons transfer from the interface to the substrate—this leads to a reduction in the polarized spin density near the interface and ultimately drives a transition to the PM phase. Our results reveal that the magnetic moments of Fe atoms in FeSe/STO with a TiOx interface structure increase with increasing atomic layer thickness, whereas those in FeSe/STO without a TiOx interface structure exhibit the opposite trend (i.e., decreasing). In addition, compared with the previously reported band structure, the additional Ti-derived bands crossing the Fermi energy are absent. More importantly, we can observe the replica band near the M point, which is in agreement with previously reported results. Our results indicate that the magnetic properties of the FeSe/STO interface are critical to achieving high-temperature superconductivity.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"26 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145729114","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}
Difference-frequency generation (DFG) is a powerful technique for generating widely tunable infrared radiation. However, conventional phase-matching schemes may require tuning multiple parameters—such as the wavelengths, crystal temperature, crystal angle, and poling period—to achieve wide tunability, which increases the complexity of practical operation. In this work, we employ a backward quasi-phase-matching scheme with distinctive tuning characteristics and demonstrate pump-enhanced continuous-wave DFG output tunable from 1751 to 2451 nm (700 nm range) in a bulk crystal. The tuning is achieved solely by varying the pump wavelength and the signal wavelength (less than 5 nm), enabling continuous, rapid, and room-temperature operation. The tuning characteristics, power-scaling behavior, and output stability are experimentally verified with the idler wavelength set at 2000 nm. The approach offers a paradigm for widely tunable infrared radiation generation and holds promise for applications in spectroscopy and biomedical sensing.
{"title":"Widely tunable cavity-enhanced backward difference-frequency generation","authors":"Ming-Yuan Gao, Yue-Wei Song, Ren-Hui Chen, Yin-Hai Li, Zhi-Yuan Zhou, Bao-Sen Shi","doi":"10.1063/5.0302624","DOIUrl":"https://doi.org/10.1063/5.0302624","url":null,"abstract":"Difference-frequency generation (DFG) is a powerful technique for generating widely tunable infrared radiation. However, conventional phase-matching schemes may require tuning multiple parameters—such as the wavelengths, crystal temperature, crystal angle, and poling period—to achieve wide tunability, which increases the complexity of practical operation. In this work, we employ a backward quasi-phase-matching scheme with distinctive tuning characteristics and demonstrate pump-enhanced continuous-wave DFG output tunable from 1751 to 2451 nm (700 nm range) in a bulk crystal. The tuning is achieved solely by varying the pump wavelength and the signal wavelength (less than 5 nm), enabling continuous, rapid, and room-temperature operation. The tuning characteristics, power-scaling behavior, and output stability are experimentally verified with the idler wavelength set at 2000 nm. The approach offers a paradigm for widely tunable infrared radiation generation and holds promise for applications in spectroscopy and biomedical sensing.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"24 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145728673","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}
Qihua Gong, Weiwei He, Ziming Tang, Yan Yin, Min Yi
Flexomagnetism, a coupling between strain gradient and magnetization, offers an alternative pathway to tune the magnetocaloric effect (MCE) by leveraging huge strain gradients in monolayers. Herein, we demonstrate that shear-strain gradient can modulate the Dzyaloshinskii–Moriya interaction in monolayer CrN and then influence the external magnetic field-induced magnetization reversal process characterized by topological magnetic textures, ultimately enabling tuning of the MCE. It is found that strain gradient can increase the isothermal magnetic entropy change (ΔSM) and adiabatic temperature change (ΔTad) of monolayer CrN. A shear-strain gradient of 3 × 107/m was seen to effectively tune ΔSM at low temperatures due to the entropic contribution associated with the topological-to-ferromagnetic magnetic phase transition. Our results suggest a new route to tailor the MCE of monolayers via strain gradients by exploiting flexomagnetism.
{"title":"Tuning magnetocaloric effect of monolayer via flexomagnetism","authors":"Qihua Gong, Weiwei He, Ziming Tang, Yan Yin, Min Yi","doi":"10.1063/5.0299212","DOIUrl":"https://doi.org/10.1063/5.0299212","url":null,"abstract":"Flexomagnetism, a coupling between strain gradient and magnetization, offers an alternative pathway to tune the magnetocaloric effect (MCE) by leveraging huge strain gradients in monolayers. Herein, we demonstrate that shear-strain gradient can modulate the Dzyaloshinskii–Moriya interaction in monolayer CrN and then influence the external magnetic field-induced magnetization reversal process characterized by topological magnetic textures, ultimately enabling tuning of the MCE. It is found that strain gradient can increase the isothermal magnetic entropy change (ΔSM) and adiabatic temperature change (ΔTad) of monolayer CrN. A shear-strain gradient of 3 × 107/m was seen to effectively tune ΔSM at low temperatures due to the entropic contribution associated with the topological-to-ferromagnetic magnetic phase transition. Our results suggest a new route to tailor the MCE of monolayers via strain gradients by exploiting flexomagnetism.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"9 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145728669","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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