Isaiah Gray, Qinwen Deng, Qi Tian, Michael Chilcote, J. Steven Dodge, Matthew Brahlek, Liang Wu
α -MnTe is an antiferromagnetic semiconductor with above room temperature TN = 310 K, which is promising for spintronic applications. Recently, it was reported to be an altermagnet, containing bands with momentum-dependent spin splitting; time-resolved experimental probes of MnTe are, therefore, important both for understanding novel magnetic properties and potential device applications. We investigate ultrafast spin dynamics in epitaxial MnTe(001)/InP(111) thin films using pump-probe magneto-optical measurements in the Kerr configuration. At room temperature, we observe an oscillation mode at 55 GHz that does not appear at zero magnetic field. Combining field and polarization dependence, we identify this mode as a magnon, likely originating from inverse stimulated Raman scattering. Magnetic field-dependent oscillations persist up to at least 335 K, which could reflect coupling to known short-range magnetic order in MnTe above TN. Additionally, we observe two optical phonons at 3.6 and 4.2 THz, which broaden and redshift with increasing temperature.
{"title":"Time-resolved magneto-optical effects in the altermagnet candidate MnTe","authors":"Isaiah Gray, Qinwen Deng, Qi Tian, Michael Chilcote, J. Steven Dodge, Matthew Brahlek, Liang Wu","doi":"10.1063/5.0244878","DOIUrl":"https://doi.org/10.1063/5.0244878","url":null,"abstract":"α -MnTe is an antiferromagnetic semiconductor with above room temperature TN = 310 K, which is promising for spintronic applications. Recently, it was reported to be an altermagnet, containing bands with momentum-dependent spin splitting; time-resolved experimental probes of MnTe are, therefore, important both for understanding novel magnetic properties and potential device applications. We investigate ultrafast spin dynamics in epitaxial MnTe(001)/InP(111) thin films using pump-probe magneto-optical measurements in the Kerr configuration. At room temperature, we observe an oscillation mode at 55 GHz that does not appear at zero magnetic field. Combining field and polarization dependence, we identify this mode as a magnon, likely originating from inverse stimulated Raman scattering. Magnetic field-dependent oscillations persist up to at least 335 K, which could reflect coupling to known short-range magnetic order in MnTe above TN. Additionally, we observe two optical phonons at 3.6 and 4.2 THz, which broaden and redshift with increasing temperature.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"191 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678428","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}
Zhenzhen Xie, Zhiyong Li, Ziren Zhu, Yu Liu, Hai Wang, Ziming Wang, Fangjin Ning, Hui Li, Zhaoxiang Wang, Liemao Hu, Changjun Ke, Yijun Zheng, Wanli Zhao, Rongqing Tan
In this work, we report a long-wave infrared (LWIR) modulator based on the two-photon absorption of CO2 gas. The effect of gas pressure and laser power on the modulation under different wavelengths is discussed. A maximum modulation depth of 21.5% with a rise time (full time) less than 20 ns for a 9.36 μm laser was achieved. The gaseous modulator, which adopts a 2.75 μm laser as the pumping source, is capable of converting the pulse characteristics of the pump light into the modulation of the long-wave infrared light. It demonstrates promising potential for applications in the rapid optical modulation of LWIR lasers.
{"title":"Fast modulation of a long-wave infrared laser based on the two-photon absorption of CO2","authors":"Zhenzhen Xie, Zhiyong Li, Ziren Zhu, Yu Liu, Hai Wang, Ziming Wang, Fangjin Ning, Hui Li, Zhaoxiang Wang, Liemao Hu, Changjun Ke, Yijun Zheng, Wanli Zhao, Rongqing Tan","doi":"10.1063/5.0242976","DOIUrl":"https://doi.org/10.1063/5.0242976","url":null,"abstract":"In this work, we report a long-wave infrared (LWIR) modulator based on the two-photon absorption of CO2 gas. The effect of gas pressure and laser power on the modulation under different wavelengths is discussed. A maximum modulation depth of 21.5% with a rise time (full time) less than 20 ns for a 9.36 μm laser was achieved. The gaseous modulator, which adopts a 2.75 μm laser as the pumping source, is capable of converting the pulse characteristics of the pump light into the modulation of the long-wave infrared light. It demonstrates promising potential for applications in the rapid optical modulation of LWIR lasers.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"191 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678433","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}
Yaping Liu, Jiayi Zhang, Tian Qin, Hongyu Du, Bo Yang, Shifeng Zhao
Traditional photoelectric semiconductors with single-source energy sensing or hybrid energy sensing integrated with other materials constrain their effectiveness in achieving power stability and device miniaturization. In contrast, photoferroelectrics offer multiple energy responses to electric, thermal, and light fields within a single material, thereby regulating the photoelectric sensing performances. This work proposes a multi-field coupling effect involving electrical, thermal, and light fields to enhance photoelectric sensing performances in electroneutral ion group doped BiFeO3 photoferroelectrics with synergistic improvement in polarization, bandgap, and leakage properties. Notably, the photocurrent output is significantly engineered by applying dual-field modes of pre-poling or thermal coupled light fields compared with the light field sensing solely. More importantly, the responsivity of the optimized photoelectric sensors is increased by nearly five times when pre-poling and thermal fields are applied simultaneously, providing convincible evidence of the sensing enhancement derived from the multi-field coupling effect. This work provides a feasible strategy to improve the photoelectric sensors through multi-field coupling, promoting the application of multifunctional photoelectric devices.
{"title":"Electric and thermal coupled light fields regulating photoelectric sensing performance in photoferroelectrics","authors":"Yaping Liu, Jiayi Zhang, Tian Qin, Hongyu Du, Bo Yang, Shifeng Zhao","doi":"10.1063/5.0237993","DOIUrl":"https://doi.org/10.1063/5.0237993","url":null,"abstract":"Traditional photoelectric semiconductors with single-source energy sensing or hybrid energy sensing integrated with other materials constrain their effectiveness in achieving power stability and device miniaturization. In contrast, photoferroelectrics offer multiple energy responses to electric, thermal, and light fields within a single material, thereby regulating the photoelectric sensing performances. This work proposes a multi-field coupling effect involving electrical, thermal, and light fields to enhance photoelectric sensing performances in electroneutral ion group doped BiFeO3 photoferroelectrics with synergistic improvement in polarization, bandgap, and leakage properties. Notably, the photocurrent output is significantly engineered by applying dual-field modes of pre-poling or thermal coupled light fields compared with the light field sensing solely. More importantly, the responsivity of the optimized photoelectric sensors is increased by nearly five times when pre-poling and thermal fields are applied simultaneously, providing convincible evidence of the sensing enhancement derived from the multi-field coupling effect. This work provides a feasible strategy to improve the photoelectric sensors through multi-field coupling, promoting the application of multifunctional photoelectric devices.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"34 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678995","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}
Lian Feng, Ling Song, Zeqi Yang, Jieni Song, Wanting Peng, Zhenru Wu, Lin Huang, Yan Luo
Microwave ablation is the most commonly used minimally invasive technique for thermal ablation of liver tumors, and accurate monitoring of the ablation area is crucial for evaluating treatment efficacy. While traditional imaging techniques play an important role in clinical monitoring, they still face several insurmountable challenges. Microwave-induced thermoacoustic imaging (TAI) has emerged as a promising modality for ablation detection due to its high resolution and deep imaging capabilities. To further enhance the effectiveness of TAI in ablation monitoring, we propose a technique based on thermoacoustic changes in backscattered energy (CBE) imaging. This method accurately delineates the liver ablation area by monitoring temperature variations before and after ablation. Experimental results show that thermoacoustic CBE imaging offers significant advantages over traditional TAI, achieving accuracies of 97.12% in ex vivo and 93.46% in in vivo experiments. Its superior resolution makes it an ideal choice for monitoring tissue damage during microwave ablation.
微波消融是最常用的肝脏肿瘤热消融微创技术，而准确监测消融区域对于评估治疗效果至关重要。虽然传统成像技术在临床监测中发挥着重要作用，但仍面临着一些难以克服的挑战。微波诱导热声成像（TAI）因其高分辨率和深度成像能力，已成为一种很有前景的消融检测模式。为了进一步提高热声成像在消融监测中的有效性，我们提出了一种基于热声变化反向散射能量（CBE）成像的技术。该方法通过监测消融前后的温度变化，准确划定肝脏消融区域。实验结果表明，热声 CBE 成像与传统的 TAI 相比具有显著优势，在体外实验和体内实验中的准确率分别达到 97.12% 和 93.46%。其卓越的分辨率使其成为监测微波消融过程中组织损伤的理想选择。
{"title":"Thermoacoustic CBE imaging for monitoring microwave ablation of the liver: A feasibility study","authors":"Lian Feng, Ling Song, Zeqi Yang, Jieni Song, Wanting Peng, Zhenru Wu, Lin Huang, Yan Luo","doi":"10.1063/5.0242212","DOIUrl":"https://doi.org/10.1063/5.0242212","url":null,"abstract":"Microwave ablation is the most commonly used minimally invasive technique for thermal ablation of liver tumors, and accurate monitoring of the ablation area is crucial for evaluating treatment efficacy. While traditional imaging techniques play an important role in clinical monitoring, they still face several insurmountable challenges. Microwave-induced thermoacoustic imaging (TAI) has emerged as a promising modality for ablation detection due to its high resolution and deep imaging capabilities. To further enhance the effectiveness of TAI in ablation monitoring, we propose a technique based on thermoacoustic changes in backscattered energy (CBE) imaging. This method accurately delineates the liver ablation area by monitoring temperature variations before and after ablation. Experimental results show that thermoacoustic CBE imaging offers significant advantages over traditional TAI, achieving accuracies of 97.12% in ex vivo and 93.46% in in vivo experiments. Its superior resolution makes it an ideal choice for monitoring tissue damage during microwave ablation.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"1 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678424","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}
Juyeon Won, Rong Zhang, Cheng Peng, Ravhi Kumar, Mebatsion S. Gebre, Dmitry Popov, Russell J. Hemley, Barry Bradlyn, Thomas P. Devereaux, Daniel P. Shoemaker
Recent band structure calculations have suggested the potential for band tuning in the chiral semiconductor Ag3AuTe2 to zero upon application of negative strain. In this study, we report on the synthesis of polycrystalline Ag3AuTe2 and investigate its transport and optical properties and mechanical compressibility. Transport measurements reveal the semiconducting behavior of Ag3AuTe2 with high resistivity and an activation energy Ea of 0.2 eV. The optical bandgap determined by diffuse reflectance measurements is about three times wider than the experimental Ea. Despite the difference, both experimental gaps fall within the range of predicted bandgaps by our first-principles density functional theory (DFT) calculations employing the Perdew–Burke–Ernzerhof and modified Becke–Johnson methods. Furthermore, our DFT simulations predict a progressive narrowing of the bandgap under compressive strain, with a full closure expected at a strain of −4% relative to the lattice parameter. To evaluate the feasibility of gap tunability at such substantial strain, the high-pressure behavior of Ag3AuTe2 was investigated by in situ high-pressure x-ray diffraction up to 47 GPa. Mechanical compression beyond 4% resulted in a pressure-induced structural transformation, indicating the possibility of substantial gap modulation under extreme compression conditions.
最近的能带结构计算表明，在施加负应变时，手性半导体 Ag3AuTe2 的能带有可能调谐为零。在本研究中，我们报告了多晶 Ag3AuTe2 的合成，并研究了其传输和光学特性以及机械可压缩性。传输测量显示，Ag3AuTe2 具有高电阻率和 0.2 eV 的活化能 Ea 的半导体行为。通过漫反射测量确定的光带隙比实验 Ea 宽约三倍。尽管存在差异，但根据我们采用 Perdew-Burke-Ernzerhof 和改进的 Becke-Johnson 方法进行的第一原理密度泛函理论（DFT）计算，这两个实验带隙都在预测带隙的范围之内。此外，我们的 DFT 模拟预测带隙在压缩应变下会逐渐变窄，预计在相对于晶格参数的应变为 -4% 时会完全关闭。为了评估在如此大的应变下实现带隙可调的可行性，我们通过高达 47 GPa 的原位高压 X 射线衍射研究了 Ag3AuTe2 的高压行为。超过 4% 的机械压缩会导致压力诱导的结构转变，这表明在极端压缩条件下存在大幅间隙调节的可能性。
{"title":"High-pressure characterization of Ag3AuTe2: Implications for strain-induced band tuning","authors":"Juyeon Won, Rong Zhang, Cheng Peng, Ravhi Kumar, Mebatsion S. Gebre, Dmitry Popov, Russell J. Hemley, Barry Bradlyn, Thomas P. Devereaux, Daniel P. Shoemaker","doi":"10.1063/5.0223472","DOIUrl":"https://doi.org/10.1063/5.0223472","url":null,"abstract":"Recent band structure calculations have suggested the potential for band tuning in the chiral semiconductor Ag3AuTe2 to zero upon application of negative strain. In this study, we report on the synthesis of polycrystalline Ag3AuTe2 and investigate its transport and optical properties and mechanical compressibility. Transport measurements reveal the semiconducting behavior of Ag3AuTe2 with high resistivity and an activation energy Ea of 0.2 eV. The optical bandgap determined by diffuse reflectance measurements is about three times wider than the experimental Ea. Despite the difference, both experimental gaps fall within the range of predicted bandgaps by our first-principles density functional theory (DFT) calculations employing the Perdew–Burke–Ernzerhof and modified Becke–Johnson methods. Furthermore, our DFT simulations predict a progressive narrowing of the bandgap under compressive strain, with a full closure expected at a strain of −4% relative to the lattice parameter. To evaluate the feasibility of gap tunability at such substantial strain, the high-pressure behavior of Ag3AuTe2 was investigated by in situ high-pressure x-ray diffraction up to 47 GPa. Mechanical compression beyond 4% resulted in a pressure-induced structural transformation, indicating the possibility of substantial gap modulation under extreme compression conditions.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"60 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678469","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 thermoelectricity, the stacking faults (SFs) have been investigated mainly in phonon transport but rarely in carrier transport. For the layered thermoelectric materials, the layered nature makes them prone to SFs, especially under high pressure because of the induced shear stress between grains. Herein, we take the typical layered 2H-MoS2 as an example to investigate the effect of high-pressure in situ-induced SFs on the thermoelectric transport properties under high pressure and high temperature. It was found that a continuous transition of P-N-P type conductive behavior with increasing pressure was observed in the sign of Seebeck coefficient, finally leading to a not weakened Seebeck coefficient. Furthermore, the in situ-induced SFs enhanced the interlayer interaction and provided transport channels for carriers across the interlayers to boost the electrical conductivity to ∼11 100 S m−1 at 5.5 GPa, 1110 K. Consequently, combined with intrinsic ultralow thermal conductivity of MoS2, a maximum ZT value of 0.191 was obtained at 5.5 GPa, 1110 K, comparable to those doped/composited MoS2. This conduction-type transition induced synergistic optimization on Seebeck coefficient and electrical conductivity could be ascribed to that SFs, which had a progressive evolution process for stabilization with rising pressure, in which some associated defects might be induced, and the band structure could be modified for regulating the carrier distributions and the density of states around the Fermi level. This study provided profound insights of regulating conduction type via dynamically modulating the lattice defects for designing a high-efficiency TE device.
在热电领域，堆叠断层（SFs）的研究主要涉及声子传输，但很少涉及载流子传输。对于层状热电材料来说，层状特性使其容易产生堆叠断层，尤其是在高压下，因为晶粒间存在诱导剪应力。在此，我们以典型的层状 2H-MoS2 为例，研究高压原位诱导 SFs 对高压高温下热电传输特性的影响。研究发现，随着压力的增加，塞贝克系数的符号出现了 P-N-P 型导电行为的连续转变，最终导致塞贝克系数没有减弱。此外，原位诱导的 SFs 增强了层间相互作用，并为载流子穿过层间提供了传输通道，从而将 5.5 GPa、1110 K 时的电导率提高到 ∼11 100 S m-1。因此，结合 MoS2 固有的超低热导率，在 5.5 GPa、1110 K 时获得的最大 ZT 值为 0.191，与那些掺杂/复合 MoS2 相当。这种诱导塞贝克系数和电导率协同优化的传导型转变可归因于 SFs 随着压力的升高而逐渐稳定的演化过程，在这一过程中，可能会诱发一些相关的缺陷，从而改变带状结构以调节费米级附近的载流子分布和态密度。这项研究为通过动态调节晶格缺陷来调节传导类型，从而设计出高效 TE 器件提供了深刻的见解。
{"title":"Synergistic optimization on Seebeck coefficient and electrical conductivity in 2H-MoS2 enabled by progressively evolved stacking faults under high pressure and high temperature","authors":"Dianzhen Wang, Jing Zou, Cun You, Yufei Ge, Xinglin Wang, Xiao Liang, Qiang Zhou, Qiang Tao, Yanli Chen, Pinwen Zhu, Tian Cui","doi":"10.1063/5.0238663","DOIUrl":"https://doi.org/10.1063/5.0238663","url":null,"abstract":"In thermoelectricity, the stacking faults (SFs) have been investigated mainly in phonon transport but rarely in carrier transport. For the layered thermoelectric materials, the layered nature makes them prone to SFs, especially under high pressure because of the induced shear stress between grains. Herein, we take the typical layered 2H-MoS2 as an example to investigate the effect of high-pressure in situ-induced SFs on the thermoelectric transport properties under high pressure and high temperature. It was found that a continuous transition of P-N-P type conductive behavior with increasing pressure was observed in the sign of Seebeck coefficient, finally leading to a not weakened Seebeck coefficient. Furthermore, the in situ-induced SFs enhanced the interlayer interaction and provided transport channels for carriers across the interlayers to boost the electrical conductivity to ∼11 100 S m−1 at 5.5 GPa, 1110 K. Consequently, combined with intrinsic ultralow thermal conductivity of MoS2, a maximum ZT value of 0.191 was obtained at 5.5 GPa, 1110 K, comparable to those doped/composited MoS2. This conduction-type transition induced synergistic optimization on Seebeck coefficient and electrical conductivity could be ascribed to that SFs, which had a progressive evolution process for stabilization with rising pressure, in which some associated defects might be induced, and the band structure could be modified for regulating the carrier distributions and the density of states around the Fermi level. This study provided profound insights of regulating conduction type via dynamically modulating the lattice defects for designing a high-efficiency TE device.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"14 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142679001","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}
Qiqige Wulan, Lu Liu, Li Xing, Jiachen Yu, Jingyu Wang, Zhijun Liu
Metamaterial multipolar mode presents a compelling scheme for exploring fundamental properties and technological applications of light-matter interactions due to its strong near field and high quality factor. In this work, we demonstrate strong coupling and mode hybridization between metamaterial quadrupolar mode and molecular vibration in the mid-infrared. In our fabricated cross-shaped metasurfaces spin-coated with a polydimethylsiloxane (PDMS) film, a quadrupolar resonance with a quality factor of 33 is excited at oblique incidence, whose electric dipolar component efficiently couples to the Si-CH3 vibration with pronounced spectral splitting and anti-crossing behaviors. The coupling strength increases with the PDMS film thickness and reaches the strong coupling regime for thickness above 27 nm. A Rabi splitting of 0.79–1.13 THz is measured in the strong coupling regime. Our results indicate that the use of quadrupolar mode in plasmonic nanostructures provides an effective and convenient approach for the realization of vibrational polaritons, which hold promise for applications in ultrasensitive infrared sensing and photochemistry.
{"title":"Strong coupling of metamaterial quadrupolar mode with molecular vibration","authors":"Qiqige Wulan, Lu Liu, Li Xing, Jiachen Yu, Jingyu Wang, Zhijun Liu","doi":"10.1063/5.0230762","DOIUrl":"https://doi.org/10.1063/5.0230762","url":null,"abstract":"Metamaterial multipolar mode presents a compelling scheme for exploring fundamental properties and technological applications of light-matter interactions due to its strong near field and high quality factor. In this work, we demonstrate strong coupling and mode hybridization between metamaterial quadrupolar mode and molecular vibration in the mid-infrared. In our fabricated cross-shaped metasurfaces spin-coated with a polydimethylsiloxane (PDMS) film, a quadrupolar resonance with a quality factor of 33 is excited at oblique incidence, whose electric dipolar component efficiently couples to the Si-CH3 vibration with pronounced spectral splitting and anti-crossing behaviors. The coupling strength increases with the PDMS film thickness and reaches the strong coupling regime for thickness above 27 nm. A Rabi splitting of 0.79–1.13 THz is measured in the strong coupling regime. Our results indicate that the use of quadrupolar mode in plasmonic nanostructures provides an effective and convenient approach for the realization of vibrational polaritons, which hold promise for applications in ultrasensitive infrared sensing and photochemistry.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"74 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678996","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}
Quasi-bound states in the continuum (QBIC) can significantly localize the light field and enhance light–matter interactions at the nanoscale, providing a platform for high-Q chiral light response and promoting nonlinear effects of materials. In this work, we numerically study the chiral linear and nonlinear light responses of the QBIC lithium niobate (LN) metasurface and achieve chirality modulation. The designed metasurface consists of LN nanobar dimers, and the chiral QBIC mode is excited by breaking the in-plane and out-of-plane symmetries of the structure, with the circular dichroism (CD) value and Q-factor reaching 0.92 and 1.24×104, respectively. Then, we investigate the second harmonic generation (SHG) of this device. The conversion efficiency of SHG under right circularly polarized pumping reaches 7.3×10−3, which is more than three orders of magnitude higher than that under the left circularly polarized pumping. The corresponding CD value of SHG reaches 0.99. In addition, by introducing phase change materials, we study the active modulation of the chiroptical response. Our results provide a crucial route for high-quality chiral light sources.
{"title":"Nonlinear chiroptical response in lithium niobate metasurface driven by quasi-bound states in the continuum","authors":"Hong Duan, Haoxuan He, Yingfei Yi, Lulu Wang, Ying Zhang, Xia Yan, Jing Huang, Chaobiao Zhou","doi":"10.1063/5.0242454","DOIUrl":"https://doi.org/10.1063/5.0242454","url":null,"abstract":"Quasi-bound states in the continuum (QBIC) can significantly localize the light field and enhance light–matter interactions at the nanoscale, providing a platform for high-Q chiral light response and promoting nonlinear effects of materials. In this work, we numerically study the chiral linear and nonlinear light responses of the QBIC lithium niobate (LN) metasurface and achieve chirality modulation. The designed metasurface consists of LN nanobar dimers, and the chiral QBIC mode is excited by breaking the in-plane and out-of-plane symmetries of the structure, with the circular dichroism (CD) value and Q-factor reaching 0.92 and 1.24×104, respectively. Then, we investigate the second harmonic generation (SHG) of this device. The conversion efficiency of SHG under right circularly polarized pumping reaches 7.3×10−3, which is more than three orders of magnitude higher than that under the left circularly polarized pumping. The corresponding CD value of SHG reaches 0.99. In addition, by introducing phase change materials, we study the active modulation of the chiroptical response. Our results provide a crucial route for high-quality chiral light sources.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"57 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678423","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 flexoelectric effect is an electro-mechanical coupling between strain gradients and the electric polarization, and it is especially significant for nanoscale structures. Since the strain gradient scales up with the decrease in the sample's feature size, the flexoelectric effect is size dependent. Due to the stress concentration, large strain gradients can be found at the crack tip and result in significant flexoelectric effect. However, for micro- or nanoscale cracks, it is still not clear how the flexoelectric effect changes with the size of cracks. In practice, the crack tip has finite radius. So, in addition to the crack length, the crack tip radius is also one of the geometric parameters describing the size of nanocracks. In this work, using our collocation mixed finite element method (CMFEM), we study the size dependence of flexoelectricity around nanocracks through these two parameters. Numerical simulation results indicate that stronger flexoelectric field can be formed around the tip of cracks with either larger crack length or smaller tip radius. We also analyze the interplay of the crack length and the tip radius and show how the crack tip flexoelectric field varies when both of these two parameters are changing.
{"title":"The size dependence of flexoelectricity at nanocracks","authors":"Yihan Hao, Mengkang Xu, Xinpeng Tian, Qian Deng","doi":"10.1063/5.0238742","DOIUrl":"https://doi.org/10.1063/5.0238742","url":null,"abstract":"The flexoelectric effect is an electro-mechanical coupling between strain gradients and the electric polarization, and it is especially significant for nanoscale structures. Since the strain gradient scales up with the decrease in the sample's feature size, the flexoelectric effect is size dependent. Due to the stress concentration, large strain gradients can be found at the crack tip and result in significant flexoelectric effect. However, for micro- or nanoscale cracks, it is still not clear how the flexoelectric effect changes with the size of cracks. In practice, the crack tip has finite radius. So, in addition to the crack length, the crack tip radius is also one of the geometric parameters describing the size of nanocracks. In this work, using our collocation mixed finite element method (CMFEM), we study the size dependence of flexoelectricity around nanocracks through these two parameters. Numerical simulation results indicate that stronger flexoelectric field can be formed around the tip of cracks with either larger crack length or smaller tip radius. We also analyze the interplay of the crack length and the tip radius and show how the crack tip flexoelectric field varies when both of these two parameters are changing.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"230 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678467","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) ferroelectricity has attracted great interest for its potential to develop various flexible and stretchable ultra-thin smart devices. The ultra-thin nature of 2D materials makes domain control very challenging, as an external electric field inevitably leads to leakage currents and even material breakdown. Therefore, it is highly desirable to explore more practical and feasible methods to control ferroelectric (FE) domains. In this work, based on the coupling between the ferroelasticity and ferroelectricity in 2D multiferroic materials, we propose a strategy to control the FE polarization direction and domain through the strain engineering. Taking β′-In2Se3 as an example, we revealed the regulation mechanism of the uniaxial strain and shear strain on the ferroelasticity and ferroelectricity. We found that the polarization direction of FE β′-In2Se3 is tunable by manipulating the strain, which demonstrates the feasibility to tailor the FE single domain as well as domain wall (DW) patterns. In addition, we also found that the angle between the stretching direction and the DW plays a crucial role in regulating the DW type, which provides an important reference for controlling DW. Therefore, the strain engineering not only provides an alternative solution for forming large-sized single domain FE materials, but also enable customized FE domain structures for DW electronics by ingeniously designing strain patterns.
二维（2D）铁电性因其在开发各种柔性和可拉伸超薄智能设备方面的潜力而备受关注。二维材料的超薄特性使得畴控制非常具有挑战性，因为外部电场不可避免地会导致漏电流甚至材料击穿。因此，探索更切实可行的方法来控制铁电（FE）畴是非常可取的。在这项工作中，我们基于二维多铁电体材料中铁弹性和铁电性之间的耦合关系，提出了一种通过应变工程控制铁电极化方向和铁电畴的策略。以β′-In2Se3为例，我们揭示了单轴应变和剪切应变对铁弹性和铁电性的调控机制。我们发现 FE β′-In2Se3 的极化方向可通过操纵应变进行调控，这证明了定制 FE 单畴以及畴壁（DW）模式的可行性。此外，我们还发现拉伸方向与畴壁之间的角度在调节畴壁类型中起着关键作用，这为控制畴壁提供了重要参考。因此，应变工程不仅为形成大尺寸单畴 FE 材料提供了另一种解决方案，而且通过巧妙地设计应变模式，还能为 DW 电子器件定制 FE 域结构。
{"title":"Strain engineering of ferroelectric polarization and domain in the two-dimensional multiferroic semiconductor","authors":"Lijing Gao, Xiaofang Chen, Jingshan Qi","doi":"10.1063/5.0239890","DOIUrl":"https://doi.org/10.1063/5.0239890","url":null,"abstract":"Two-dimensional (2D) ferroelectricity has attracted great interest for its potential to develop various flexible and stretchable ultra-thin smart devices. The ultra-thin nature of 2D materials makes domain control very challenging, as an external electric field inevitably leads to leakage currents and even material breakdown. Therefore, it is highly desirable to explore more practical and feasible methods to control ferroelectric (FE) domains. In this work, based on the coupling between the ferroelasticity and ferroelectricity in 2D multiferroic materials, we propose a strategy to control the FE polarization direction and domain through the strain engineering. Taking β′-In2Se3 as an example, we revealed the regulation mechanism of the uniaxial strain and shear strain on the ferroelasticity and ferroelectricity. We found that the polarization direction of FE β′-In2Se3 is tunable by manipulating the strain, which demonstrates the feasibility to tailor the FE single domain as well as domain wall (DW) patterns. In addition, we also found that the angle between the stretching direction and the DW plays a crucial role in regulating the DW type, which provides an important reference for controlling DW. Therefore, the strain engineering not only provides an alternative solution for forming large-sized single domain FE materials, but also enable customized FE domain structures for DW electronics by ingeniously designing strain patterns.","PeriodicalId":8094,"journal":{"name":"Applied Physics Letters","volume":"73 1","pages":""},"PeriodicalIF":4.0,"publicationDate":"2024-11-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678426","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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