Paul C. A. Hagen, Mathieu Bozzio, Moritz Cygorek, Doris E. Reiter, Vollrath M. Axt
Semiconductor quantum dots are a versatile source of single photons with tunable properties to be used in quantum-cryptographic applications. A crucial figure of merit of the emitted photons is photon number coherence (PNC), which impacts the security of many quantum communication protocols. In the process of single-photon generation, the quantum dot as a solid-state object is subject to an interaction with phonons, which can therefore indirectly affect the PNC. In this paper, we elaborate on the origin of PNC in optically excited quantum dots and how it is affected by phonons. In contrast to the expectation that phonons always deteriorate coherence, PNC can be increased in a quantum dot-cavity system due to the electron-phonon interaction.
{"title":"Photon Number Coherence in Quantum Dot-Cavity Systems can be Enhanced by Phonons","authors":"Paul C. A. Hagen, Mathieu Bozzio, Moritz Cygorek, Doris E. Reiter, Vollrath M. Axt","doi":"arxiv-2409.08643","DOIUrl":"https://doi.org/arxiv-2409.08643","url":null,"abstract":"Semiconductor quantum dots are a versatile source of single photons with\u0000tunable properties to be used in quantum-cryptographic applications. A crucial\u0000figure of merit of the emitted photons is photon number coherence (PNC), which\u0000impacts the security of many quantum communication protocols. In the process of\u0000single-photon generation, the quantum dot as a solid-state object is subject to\u0000an interaction with phonons, which can therefore indirectly affect the PNC. In\u0000this paper, we elaborate on the origin of PNC in optically excited quantum dots\u0000and how it is affected by phonons. In contrast to the expectation that phonons\u0000always deteriorate coherence, PNC can be increased in a quantum dot-cavity\u0000system due to the electron-phonon interaction.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"106 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Guoshuai Du, Lili Zhao, Shuchang Li, Jing Huang, Susu Fang, Wuxiao Han, Jiayin Li, Yubing Du, Jiaxin Ming, Tiansong Zhang, Jun Zhang, Jun Kang, Xiaoyan Li, Weigao Xu, Yabin Chen
Interlayer coupling in two-dimensional (2D) layered nanomaterials can provide us novel strategies to evoke their superior properties, such as the exotic flat bands and unconventional superconductivity of twisted layers, the formation of moir'e excitons and related nontrivial topology. However, to accurately quantify interlayer potential and further measure elastic properties of 2D materials remains vague, despite significant efforts. Herein, the layer-dependent lattice dynamics and elastic constants of 2D nanomaterials have been systematically investigated via pressure-engineering strategy based on ultralow frequency Raman spectroscopy. The shearing mode and layer-breathing Raman shifts of MoS2 with various thicknesses were analyzed by the linear chain model. Intriguingly, it was found that the layer-dependent d{omega}/dP of shearing and breathing Raman modes display the opposite trends, quantitatively consistent with our molecular dynamics simulations and density functional theory calculations. These results can be generalized to other van der Waals systems, and may shed light on the potential applications of 2D materials in nanomechanics and nanoelectronics.
{"title":"Interlayer Engineering of Lattice Dynamics and Elastic Constants of 2D Layered Nanomaterials under Pressure","authors":"Guoshuai Du, Lili Zhao, Shuchang Li, Jing Huang, Susu Fang, Wuxiao Han, Jiayin Li, Yubing Du, Jiaxin Ming, Tiansong Zhang, Jun Zhang, Jun Kang, Xiaoyan Li, Weigao Xu, Yabin Chen","doi":"arxiv-2409.07698","DOIUrl":"https://doi.org/arxiv-2409.07698","url":null,"abstract":"Interlayer coupling in two-dimensional (2D) layered nanomaterials can provide\u0000us novel strategies to evoke their superior properties, such as the exotic flat\u0000bands and unconventional superconductivity of twisted layers, the formation of\u0000moir'e excitons and related nontrivial topology. However, to accurately\u0000quantify interlayer potential and further measure elastic properties of 2D\u0000materials remains vague, despite significant efforts. Herein, the\u0000layer-dependent lattice dynamics and elastic constants of 2D nanomaterials have\u0000been systematically investigated via pressure-engineering strategy based on\u0000ultralow frequency Raman spectroscopy. The shearing mode and layer-breathing\u0000Raman shifts of MoS2 with various thicknesses were analyzed by the linear chain\u0000model. Intriguingly, it was found that the layer-dependent d{omega}/dP of\u0000shearing and breathing Raman modes display the opposite trends, quantitatively\u0000consistent with our molecular dynamics simulations and density functional\u0000theory calculations. These results can be generalized to other van der Waals\u0000systems, and may shed light on the potential applications of 2D materials in\u0000nanomechanics and nanoelectronics.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Alexander Rothstein, Ammon Fischer, Anthony Achtermann, Eike Icking, Katrin Hecker, Luca Banszerus, Martin Otto, Stefan Trellenkamp, Florian Lentz, Kenji Watanabe, Takashi Taniguchi, Bernd Beschoten, Robin J. Dolleman, Dante M. Kennes, Christoph Stampfer
Twisted bilayer graphene (tBLG) near the magic angle is an interesting platform to study correlated electronic phases. These phases are gate-tunable and are closely related to the presence of flat electronic bands, isolated by single-particle band gaps. This allows electrostatically controlled confinement of charge carriers in the flat bands to explore the interplay between confinement, band renormalisation, electron-electron interactions and the moir'e superlattice, potentially revealing key mechanisms underlying these electronic phases. Here, we show gate-controlled flat-band charge carrier confinement in near-magic-angle tBLG, resulting in well-tunable Coulomb blockade resonances arising from the charging of electrostatically defined islands in tBLG. Coulomb resonance measurements allow to study magnetic field-induced quantum oscillations in the density of states of the source-drain reservoirs, providing insight into the gate-tunable Fermi surfaces of tBLG. Comparison with tight-binding calculations emphasises the importance of displacement-field-induced band renormalisation, which is crucial for future advanced gate-tunable quantum devices and circuits in tBLG.
{"title":"Gate-defined flat-band charge carrier confinement in twisted bilayer graphene","authors":"Alexander Rothstein, Ammon Fischer, Anthony Achtermann, Eike Icking, Katrin Hecker, Luca Banszerus, Martin Otto, Stefan Trellenkamp, Florian Lentz, Kenji Watanabe, Takashi Taniguchi, Bernd Beschoten, Robin J. Dolleman, Dante M. Kennes, Christoph Stampfer","doi":"arxiv-2409.08154","DOIUrl":"https://doi.org/arxiv-2409.08154","url":null,"abstract":"Twisted bilayer graphene (tBLG) near the magic angle is an interesting\u0000platform to study correlated electronic phases. These phases are gate-tunable\u0000and are closely related to the presence of flat electronic bands, isolated by\u0000single-particle band gaps. This allows electrostatically controlled confinement\u0000of charge carriers in the flat bands to explore the interplay between\u0000confinement, band renormalisation, electron-electron interactions and the\u0000moir'e superlattice, potentially revealing key mechanisms underlying these\u0000electronic phases. Here, we show gate-controlled flat-band charge carrier\u0000confinement in near-magic-angle tBLG, resulting in well-tunable Coulomb\u0000blockade resonances arising from the charging of electrostatically defined\u0000islands in tBLG. Coulomb resonance measurements allow to study magnetic\u0000field-induced quantum oscillations in the density of states of the source-drain\u0000reservoirs, providing insight into the gate-tunable Fermi surfaces of tBLG.\u0000Comparison with tight-binding calculations emphasises the importance of\u0000displacement-field-induced band renormalisation, which is crucial for future\u0000advanced gate-tunable quantum devices and circuits in tBLG.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"16 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The third-order anomalous Hall effect (TOAHE) driven by Berry connection polarizability in Dirac materials offers a promising avenue for exploring quantum geometric phenomena. We investigate the role of impurity scattering on TOAHE using the semiclassical Boltzmann framework, via a comparison of the intrinsic contributions (stemming from the Berry connection polarizability effect) with the extrinsic contributions caused by the disorder. To validate our theoretical findings, we employ a generalized two-dimensional low-energy Dirac model to analytically assess the intrinsic and extrinsic contributions to the TOAHE. Our analysis reveals distinct disorder-mediated effects, including skew scattering and side jump contributions. We also elucidate their intriguing dependencies on Fermi surface anisotropy and discuss opportunities for experimental exploration.
{"title":"Hierarchy of the third-order anomalous Hall effect: from clean to disorder regime","authors":"Chanchal K. Barman, Arghya Chattopadhyay, Surajit Sarkar, Jian-Xin Zhu, Snehasish Nandy","doi":"arxiv-2409.07993","DOIUrl":"https://doi.org/arxiv-2409.07993","url":null,"abstract":"The third-order anomalous Hall effect (TOAHE) driven by Berry connection\u0000polarizability in Dirac materials offers a promising avenue for exploring\u0000quantum geometric phenomena. We investigate the role of impurity scattering on\u0000TOAHE using the semiclassical Boltzmann framework, via a comparison of the\u0000intrinsic contributions (stemming from the Berry connection polarizability\u0000effect) with the extrinsic contributions caused by the disorder. To validate\u0000our theoretical findings, we employ a generalized two-dimensional low-energy\u0000Dirac model to analytically assess the intrinsic and extrinsic contributions to\u0000the TOAHE. Our analysis reveals distinct disorder-mediated effects, including\u0000skew scattering and side jump contributions. We also elucidate their intriguing\u0000dependencies on Fermi surface anisotropy and discuss opportunities for\u0000experimental exploration.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qiaohui Zhou, Fei Wang, Ali Soleymani, Kenji Watanabe, Takashi Taniguchi, Jiang Wei, Xin Lu
The discovery of single photon emitters (SPEs) in two-dimensional (2D) layered materials has greatly inspired numerous studies towards utilizing the system for quantum science and technology. Thus, the dynamic control of SPEs, including neutral and charged emitters, is highly desirable. In addition to the electric control, strain tuning is particularly attractive for the 2D materials since it can activate SPEs which are formed upon localizing free excitons. While strain engineering has been demonstrated for free and neutral localized excitons, few were shown on charged localized excitons which require an additional gate control. In this article, we show the strain-tunable charged localized excitons by transferring a top-gated monolayer semiconductor on a relaxor ferroelectric. Importantly, we unveil an enhanced interaction between the localized oscillating dipoles and the nanodomains. We further demonstrate the strain-dependent circular polarization and tunable rates of energy shifts under a magnetic field. Our results imply that the integration of 2D materials with relaxor ferroelectrics provides a rich platform for nanophotonics and quantum photonics.
{"title":"Tuning Charged Localized Excitons in Monolayer WSe2 via Coupling to a Relaxor Ferroelectric","authors":"Qiaohui Zhou, Fei Wang, Ali Soleymani, Kenji Watanabe, Takashi Taniguchi, Jiang Wei, Xin Lu","doi":"arxiv-2409.07687","DOIUrl":"https://doi.org/arxiv-2409.07687","url":null,"abstract":"The discovery of single photon emitters (SPEs) in two-dimensional (2D)\u0000layered materials has greatly inspired numerous studies towards utilizing the\u0000system for quantum science and technology. Thus, the dynamic control of SPEs,\u0000including neutral and charged emitters, is highly desirable. In addition to the\u0000electric control, strain tuning is particularly attractive for the 2D materials\u0000since it can activate SPEs which are formed upon localizing free excitons.\u0000While strain engineering has been demonstrated for free and neutral localized\u0000excitons, few were shown on charged localized excitons which require an\u0000additional gate control. In this article, we show the strain-tunable charged\u0000localized excitons by transferring a top-gated monolayer semiconductor on a\u0000relaxor ferroelectric. Importantly, we unveil an enhanced interaction between\u0000the localized oscillating dipoles and the nanodomains. We further demonstrate\u0000the strain-dependent circular polarization and tunable rates of energy shifts\u0000under a magnetic field. Our results imply that the integration of 2D materials\u0000with relaxor ferroelectrics provides a rich platform for nanophotonics and\u0000quantum photonics.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"101 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142227705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The theory of surface photoelectric effect by twisted photons is developed. The explicit expression for the probability to record a twisted photoelectron is derived. The conditions when the surface photoelectric effect can be used as a pure source of twisted electrons are found. It is shown that the lightly doped n-InSb crystal with interface without defects at temperatures lower than $2.5$ K satisfies these conditions. The Dirac and Weyl semimetals with electron chemical potential near the top of the Dirac cone obey these conditions at temperatures lower than $60$ K and can also be employed for design of pure sources of twisted electrons by the photoelectric effect.
提出了扭曲光子的表面光电效应理论，并推导出记录扭曲光电子概率的明确表达式。找到了表面光电效应可用作扭曲电子纯源的条件。研究表明，在低于 2.5$ K 的温度下，具有无缺陷界面的轻掺杂 n-InSb 晶体满足这些条件。电子化学势接近狄拉克锥顶部的狄拉克半金属和韦尔半金属在低于 60 美元 K 的温度下也符合这些条件，因此也可以利用光电效应来设计扭曲电子的纯源。
{"title":"Surface photoelectric effect by twisted photons as a source of twisted electrons","authors":"P. O. Kazinski, M. V. Mokrinskiy, V. A. Ryakin","doi":"arxiv-2409.08152","DOIUrl":"https://doi.org/arxiv-2409.08152","url":null,"abstract":"The theory of surface photoelectric effect by twisted photons is developed.\u0000The explicit expression for the probability to record a twisted photoelectron\u0000is derived. The conditions when the surface photoelectric effect can be used as\u0000a pure source of twisted electrons are found. It is shown that the lightly\u0000doped n-InSb crystal with interface without defects at temperatures lower than\u0000$2.5$ K satisfies these conditions. The Dirac and Weyl semimetals with electron\u0000chemical potential near the top of the Dirac cone obey these conditions at\u0000temperatures lower than $60$ K and can also be employed for design of pure\u0000sources of twisted electrons by the photoelectric effect.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Umakanta Patra, Faiha Mujeeb, Abhiram K, Jai Israni, Subhabrata Dhar
Bilayer (2L) transition metal dichalcogenides (TMD) have the ability to host interlayer excitons, where electron and hole parts are spatially separated that leads to much longer lifetime as compared to direct excitons. This property can be utilized for the development of exciton-based logic devices, which are supposed to be superior in terms of energy efficiency and optical communication compatibility as compared to their electronic counterparts. However, obtaining uniformly thick bilayer epitaxial films with large area coverage is challenging. Here, we have engineered the flow pattern of the precursors over the substrate surface to obtain large area (mm2) covered strictly bilayer MoS$_2$ films on SiO$_2$ by chemical vapour deposition (CVD) technique without any plasma treatment of the substrate prior to the growth. Bilayer nature of these films is confirmed by Raman, low-frequency Raman, atomic force microscopy (AFM) and photoluminescence (PL) studies. The uniformity of the film has been checked by Raman peak separation and PL intensity map. High resolution transmission electron microscopy (HRTEM) reveals that crystalline and twisted bilayer islands coexist within the layer. Back gated field-effect transistor (FET) structures fabricated on the bilayers show on/off ratio of 10^6 and subthreshold swings (SS) of 2.5 V/Decade.
{"title":"Controlled Growth of large area bilayer MoS$_2$ films on SiO$_2$ substrates by chemical vapour deposition technique","authors":"Umakanta Patra, Faiha Mujeeb, Abhiram K, Jai Israni, Subhabrata Dhar","doi":"arxiv-2409.07921","DOIUrl":"https://doi.org/arxiv-2409.07921","url":null,"abstract":"Bilayer (2L) transition metal dichalcogenides (TMD) have the ability to host\u0000interlayer excitons, where electron and hole parts are spatially separated that\u0000leads to much longer lifetime as compared to direct excitons. This property can\u0000be utilized for the development of exciton-based logic devices, which are\u0000supposed to be superior in terms of energy efficiency and optical communication\u0000compatibility as compared to their electronic counterparts. However, obtaining\u0000uniformly thick bilayer epitaxial films with large area coverage is\u0000challenging. Here, we have engineered the flow pattern of the precursors over\u0000the substrate surface to obtain large area (mm2) covered strictly bilayer\u0000MoS$_2$ films on SiO$_2$ by chemical vapour deposition (CVD) technique without\u0000any plasma treatment of the substrate prior to the growth. Bilayer nature of\u0000these films is confirmed by Raman, low-frequency Raman, atomic force microscopy\u0000(AFM) and photoluminescence (PL) studies. The uniformity of the film has been\u0000checked by Raman peak separation and PL intensity map. High resolution\u0000transmission electron microscopy (HRTEM) reveals that crystalline and twisted\u0000bilayer islands coexist within the layer. Back gated field-effect transistor\u0000(FET) structures fabricated on the bilayers show on/off ratio of 10^6 and\u0000subthreshold swings (SS) of 2.5 V/Decade.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"25 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We theoretically study spin pumping into a spin-nematic state in a junction system composed of a ferromagnetic insulator and a spin-nematic insulator, described by using the spin-1 bilinear-biquadratic model. We analyze an increase of the Gilbert damping in ferromagnetic resonance (FMR) due to an interfacial exchange coupling within a mean-field theory based on the Schwinger boson method. We find that the two Schwinger bosons contribute in distinct ways to spin pumping. We report a detailed dependence of the spin pumping on a resonant frequency, a magnetic field, and an interface type.
{"title":"Spin pumping into quantum spin nematic states","authors":"Takuto Ishikawa, Wolfgang Belzig, Takeo Kato","doi":"arxiv-2409.08246","DOIUrl":"https://doi.org/arxiv-2409.08246","url":null,"abstract":"We theoretically study spin pumping into a spin-nematic state in a junction\u0000system composed of a ferromagnetic insulator and a spin-nematic insulator,\u0000described by using the spin-1 bilinear-biquadratic model. We analyze an\u0000increase of the Gilbert damping in ferromagnetic resonance (FMR) due to an\u0000interfacial exchange coupling within a mean-field theory based on the Schwinger\u0000boson method. We find that the two Schwinger bosons contribute in distinct ways\u0000to spin pumping. We report a detailed dependence of the spin pumping on a\u0000resonant frequency, a magnetic field, and an interface type.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"74 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Semiconductor research has shifted towards exploring two-dimensional (2D) materials as candidates for next-generation electronic devices due to the limitations of existing silicon technology. Transition Metal Dichalcogenides (TMDCs) stand out for their exceptional optoelectronic properties and potential for advanced device integration. This thesis focuses on the synthesis of 2D TMDCs using Chemical Vapor Deposition (CVD) for their potential applications in transistors, memory, and neuromorphic computing. By optimizing the NaCl-assisted CVD method and examining their optical properties through Raman and photoluminescence spectroscopy, challenges such as premature growth, defects, and non-uniformity in MoS2 samples are addressed. The thesis highlights device fabrication techniques and electrical performance of salt-assisted CVD-grown MoS2 field-effect transistors, which exhibit hysteresis-free behavior and high field-effect mobility. A novel etching-free transfer technique is introduced, improving transistor performance and enabling applications in flexible optoelectronics. The thesis also explores monolayer MoS2 mem-transistors, demonstrating multifunctional room temperature transistor and high-temperature multi-level memory behaviour. These devices leverage interfacial physics and ion dynamics to achieve non-volatile memory with multi-level storage capabilities. Additionally, high density memory devices using monolayer WS2 are developed, which demonstrate 6-bit memory operation with neuromorphic biomimetic plasticity. The study also includes 2D TMDCs and their hetero-bilayers as potential 2D dilute magnetic semiconductors via doping, strain engineering using density functional theory and micromagnetic simulations, revealing potential applications in spintronics. This thesis makes significant contributions to advancing 2D materials for next-generation electronics and spintronic devices.
{"title":"Development of large scale CVD grown two dimensional materials for field-effect transistors, thermally-driven neuromorphic memory, and spintronics applications","authors":"Sameer Kumar Mallik","doi":"arxiv-2409.07357","DOIUrl":"https://doi.org/arxiv-2409.07357","url":null,"abstract":"Semiconductor research has shifted towards exploring two-dimensional (2D)\u0000materials as candidates for next-generation electronic devices due to the\u0000limitations of existing silicon technology. Transition Metal Dichalcogenides\u0000(TMDCs) stand out for their exceptional optoelectronic properties and potential\u0000for advanced device integration. This thesis focuses on the synthesis of 2D\u0000TMDCs using Chemical Vapor Deposition (CVD) for their potential applications in\u0000transistors, memory, and neuromorphic computing. By optimizing the\u0000NaCl-assisted CVD method and examining their optical properties through Raman\u0000and photoluminescence spectroscopy, challenges such as premature growth,\u0000defects, and non-uniformity in MoS2 samples are addressed. The thesis\u0000highlights device fabrication techniques and electrical performance of\u0000salt-assisted CVD-grown MoS2 field-effect transistors, which exhibit\u0000hysteresis-free behavior and high field-effect mobility. A novel etching-free\u0000transfer technique is introduced, improving transistor performance and enabling\u0000applications in flexible optoelectronics. The thesis also explores monolayer\u0000MoS2 mem-transistors, demonstrating multifunctional room temperature transistor\u0000and high-temperature multi-level memory behaviour. These devices leverage\u0000interfacial physics and ion dynamics to achieve non-volatile memory with\u0000multi-level storage capabilities. Additionally, high density memory devices\u0000using monolayer WS2 are developed, which demonstrate 6-bit memory operation\u0000with neuromorphic biomimetic plasticity. The study also includes 2D TMDCs and\u0000their hetero-bilayers as potential 2D dilute magnetic semiconductors via\u0000doping, strain engineering using density functional theory and micromagnetic\u0000simulations, revealing potential applications in spintronics. This thesis makes\u0000significant contributions to advancing 2D materials for next-generation\u0000electronics and spintronic devices.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142226281","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Larry Li, Marcin Abram, Abhinav Prem, Stephan Haas
In this chapter, we investigate the energy spectra as well as the bulk and surface states in a two-dimensional system composed of a coupled stack of one-dimensional dimerized chains in the presence of an external magnetic field. Specifically, we analyze the Hofstadter butterfly patterns that emerge in a 2D stack of coupled 1D Su-Schrieffer-Heeger (SSH) chains subject to an external transverse magnetic field. Depending on the parameter regime, we find that the energy spectra of this hybrid topological system can exhibit topologically non-trivial bulk bands separated by energy gaps. Upon introducing boundaries into the system, we observe topologically protected in-gap surface states, which are protected either by a non-trivial Chern number or by inversion symmetry. We examine the resilience of these surface states against perturbations, confirming their expected stability against local symmetry-preserving perturbations.
{"title":"Hofstadter Butterflies in Topological Insulators","authors":"Larry Li, Marcin Abram, Abhinav Prem, Stephan Haas","doi":"arxiv-2409.07383","DOIUrl":"https://doi.org/arxiv-2409.07383","url":null,"abstract":"In this chapter, we investigate the energy spectra as well as the bulk and\u0000surface states in a two-dimensional system composed of a coupled stack of\u0000one-dimensional dimerized chains in the presence of an external magnetic field.\u0000Specifically, we analyze the Hofstadter butterfly patterns that emerge in a 2D\u0000stack of coupled 1D Su-Schrieffer-Heeger (SSH) chains subject to an external\u0000transverse magnetic field. Depending on the parameter regime, we find that the\u0000energy spectra of this hybrid topological system can exhibit topologically\u0000non-trivial bulk bands separated by energy gaps. Upon introducing boundaries\u0000into the system, we observe topologically protected in-gap surface states,\u0000which are protected either by a non-trivial Chern number or by inversion\u0000symmetry. We examine the resilience of these surface states against\u0000perturbations, confirming their expected stability against local\u0000symmetry-preserving perturbations.","PeriodicalId":501137,"journal":{"name":"arXiv - PHYS - Mesoscale and Nanoscale Physics","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142206716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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