1989 — 1993 |
Meservey, Robert [⬀] Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Ferromagnetic Insulators For Spin-Polarized Electron Tunneling Studies @ Massachusetts Institute of Technology
They will (1) study the systematics of EuS and other ferromagnetic insulators in contact with metals and as tunnel barriers of thin film tunnel junctions; (2) use the new technique, which allows for the first time tunneling measurements of spin-orbit and Fermi-liquid effects in many metals; (3) look for spin effects in heavy-electron and high temperature superconductors; (4) study the exchange effects with ferromagnetic metals, magnetic domains, and magnetic effects at surfaces for H = 0 to 30 T. This program will (1) give an understanding of exchange effects between ferromagnetic insulators and superconductors, ferromagnetic metals, and paramagnetic metals; (2) give a quantitative picture of electron tunneling through ferromagnetic insulators; (3) permit new measurements giving fundamental results in superconductivity, ferromagnetism, and electron-spin effects in normal metals.
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0.915 |
1991 — 1995 |
Meservey, Robert [⬀] Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Spin-Polarized Vacuum Tunneling Study @ Massachusetts Institute of Technology
This project will combine spin-polarized tunneling methods with some of the techniques of scanning tunneling microscopy (STM) in an ultra high vacuum environment. The techniques will be applied to probe the surface magnetism of superconducting and magnetic materials. The research will include low temperature studies of spin-orbit and magnetic scattering in superconductors, magnetic impurities in normal metals, and tunneling measurements with oriented single-crystal ferromagnets. Part of the project will involve continued development of superconducting and ferromagnetic tips crucial to operation of STM and spin polarized tunneling SSTM apparatus. Ferromagnetic to ferromagnetic tunneling measurements will be made at temperatures up to 300 K with various materials and modulation techniques. The STM techniques will initially be used to position the tunneling tip at a proper site within tunneling distance. Later the limits of spatial resolution will be investigated in the study of individual impurities or antiferromagnets. These results will be compared with theory. It is expected that this study will give information leading to eventual design of a spin-sensitive tunneling microscope with close to atomic resolution.
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0.915 |
1995 — 1998 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Spin-Polarized Electron Tunneling With Ferromagnetic Materials @ Massachusetts Institute of Technology
9423013 Moodera Experimental investigation of the properties of magnetic materials by the surface-sensitive technique of spin-polarized tunneling is the aim of this research program. In particular, electron tunneling between ferromagnetic metals, through ferromagnetic insulators, and exchange effects in ultrathin films, and at the interfaces between ferromagnetic metals and paramagnetic metals will be studied. Planar tunnel junctions will use superconductors as electron-spin detectors at low temperature and voltage. Our recent success in using ferromagnetic metals as electron-spin detectors at room temperature and higher voltages greatly broadens this field of research and suggests technological uses. %%% Improvement of computer magnetic memory systems is currently of high priority. Study of surfaces and interfaces has become increasingly pertinent from the point of present and future technology. This is a proposal for the study of the physics of magnetic effects in thin film surfaces and trilayers using the technique of spin-polarized tunneling. The recently discovered large magnetoresistance effects in ferro-magnetic tunnel junctions at room temperature promise important applications for these effects in READ/WRITE sensors and memory elements. ***
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0.915 |
1998 — 2002 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Tunneling Studies of Ferromagnetic Junctions and Interfaces @ Massachusetts Institute of Technology
9730908 Moodera This experimental research project is concerned with electron tunnel junctions with electrodes of magnetic metals conceived in such a way that the tunneling current is controlled in a sensitive fashion by an applied magnetic field. Well characterized ferromagnetic tunnel junctions and interfaces will be prepared under clean and ultra high vacuum conditions to allow accurate and reproducible tunneling measurements, particularly on structures with 3d and 4f ferromagnetic metals. Spin polarization of the same films that make up the tunnel junction will also be measured by superconducting tunneling spectroscopy. The main thrust is to understand the physical mechanisms responsible for the observed magnetic field sensitivity. It is expected that this research will additionally lead to new results and techniques in condensed matter physics and new applications for magnetic technology.This research program is interdisciplinary in nature and has typically involved several undergraduate and high school students in its activities. These involvements are beneficial in the preparation of students for further study and for careers in industry, government laboratories or academia. %%% This experimental research project is concerned with a new class of electronic devices that the PI has discovered in his previously supported work, which are highly sensitive to magnetic field. The electrical resistance of the device, which is called a tunnel junction, changes when the device is placed in a magnetic field, and is said to exhibit magnetoresistance. This discovery has created interest worldwide because of the potential for improvements in technology. The main technological applications may be in magnetic sensors for computer hard drives, possibly for magnetic computer memory or logic elements, and for miscellaneous applications s uch as sensors to measure rotational speeds, eg, a tachometer. The basic tunnel junction is a capacitor-like device with a thin insulating oxide between two metal plates. In this case the oxide layer is so thin that electrons can transfer from one plate to the other by the quantum mechanical tunneling process. This process was firmly established and understood in detail in the late 1960's by basic physics researchers who realized that a tunnel junction device, if it could be fabricated with a sufficiently thin and homogeneous oxide layer, could be instrumental to understanding the nature of superconductivity. Ivar Giaever won the Nobel Prize in Physics in 1973 for his experiments on superconductivity which were based on his development of improved fabrication techniques and a more complete understanding of the physical behavior of tunnel junctions. The present PI has gone on from these earlier basic research results to find the magnetic effects which are very promising for applications in computers and other technologies. As in the earlier case, the PI here has perfected new and more careful experimental methods to clearly reveal the theoretically expected physical effects, in this case magnetic in nature. This project focuses on careful and systematic measurements on junction structures with metal electrodes of different ferromagnetic compositions, in order to better understand and maximize the sensitivity to magnetic field. This research program is interdisciplinary in nature and has typically involved several undergraduate and high school students in its activities. These involvements are beneficial in the preparation of students for further study and for careers in industry, government laboratories or academia. ***
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0.915 |
1999 — 2004 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Us-India Cooperative Research: Role of Interface in Magnetic Interaction and Spin Polarized Tunneling @ Massachusetts Institute of Technology
9908611 Moodera
Description: This award supports the US-India Cooperative Research: Role of Interface in Magnetic Interaction and Spin Polarized Tunneling. Collaborators are Jagadeesh Moodera of the Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology and Ratnamala Chatterjee, Indian Institute of Technology, Delhi. This research will use controlled radiation damage to study the influence of defects on spin dependent transport. The study will fill a major gap in the understanding of the role of defect scattering in producing giant magnetorresistance in metallic multilayers and magnetic tunnel junctions. In addition to obtaining fundamental knowledge in incompletely understood areas of magnetism, it can lead to better magnetic materials for application.
Scope: The US PI is an acknowledged leader in thin film magnetism, superconductivity and tunneling research. His work has frequently lead to discovery. Moodera won the IBM Research Partnership Award for three consecutive years. The Indian co-PI did postdoctoral studies at MIT and has received numerous awards for research and teaching. The project brings together complimentary expertise, facilities and involves students at both institutions.
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0.915 |
2002 — 2005 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Spin Polarized Tunneling Studies in Transition Metals, Alloys and Heavy Fermions @ Massachusetts Institute of Technology
This project will explore electron spin properties, from both the fundamental physics point of view and from the viewpoint of the technologically important area of spintronics. The emphasis will be on surfaces and interfaces that form the basis of spin transport phenomena. The intention is also to extend the technique of spin-polarized tunneling into new areas: (1) Determination of its relation to crystalline direction, barrier interface, and bulk magnetic moment, (2) Analytical study of tunnel barriers. Though having been addressed for nearly thirty years by many theoretical approaches, the origin and the magnitude of the polarization values measured by tunneling remain an open question. This work will investigate the poorly understood relation between spin polarization of tunneling electrons on crystallographic orientation and surface band structure. This includes spin-polarized tunneling from epitaxial ferromagnetic films, interfacial-bonding effects and tunnel barrier properties. Fabrication techniques will manipulate the interfaces and barriers in planar thin film magnetic tunnel junctions in efforts to maximize the spin polarization values. Spin tunneling is influenced by delta dopants (with or without magnetic moment) in the tunnel barriers - mostly flipping the spins and, except for the case of Fe dopants, even enhancing the spin tunneling probability. This area is yet to be understood and will be well investigated. A state of the art MBE system makes it feasible to engineer thin films with new types of interface materials leading to unique electronic and magnetic properties. The theoretical support comes from Prof. William H. Butler of Oak Ridge National Lab whose expertise is in band structure calculations, interface effects as well as ferromagnetic tunnel junction structures. Spin tunneling studies will possibly be initiated, a first of its kind study in heavy Fermion systems, wherein temperature-induced changes and pressure-induced changes of the magnetic transitions occur. Students of all levels and postdocs will be involved in this investigation thus creating a pool of technical experts particularly in the future field of information technology - spintronics, and in general magnetism as well as thin film science.
This condensed matter physics project broaden our fundamental understanding of electron spin properties (a topic in magnetism) by using the unique tool of spin polarized tunneling technique (a quantum phenomenon). The results will contribute to the knowledge base needed for possible future spin-based information technologies. The project will build on earlier successful work in spin tunneling plus transport, and at a later stage of the program will push toward the new frontiers by examining a new class of magnetic materials, so-called heavy Fermion metals. A major goals is to expand a new and promising interaction between theorists who are now working to analyze the spin tunneling experiments. In addition, the fabrication methods, using state of the art molecular beam epitaxy tools will manipulate the material interfaces and tunnel barriers to create novel materials and to maximize the spin polarization values. Measurements will be made in ambient as well as liquid helium temperatures in the presence of a small or large magnetic field. Some of the earlier results of this project have generated worldwide interest, both experimentally and theoretically, with many major companies involved in developing nonvolatile memory elements as well as sensors for ultrahigh-density recording. The project integrates research with the education and training of high-school students, undergraduate students, graduate students and post-doctoral fellows. The training will be in spin transport and in specialized areas such as nanotechnology. The highly educated and trained people will be well prepared for careers as educators and workers in the area of spin-based information storage technology.
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0.915 |
2005 — 2012 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Spin Transport Studies in Band and Interface Tailord Materials: Towards Total Spin Polarization For Spin Electronics @ Massachusetts Institute of Technology
Nontechnical: Enabled by advances in basic research as well as driven by a rising demand for ultra-high density magnetic storage, there is an enormous interest of late in devices based on electron spin transport. In this NSF sponsored project we will investigate fundamental properties as well as applied aspects of magnetism related to this, with an expected impact on the field at the basic level as well as the future spin-based information technology. To reach this goal, spin-polarized transport studies of several novel systems will carried out, and to understand and manipulate the spin polarization, P (the degree to which transport electrons are spin polarized), and develop "tailored" materials. For example, we will explore the Cobalt-Iron_Boron alloy system, which recently demonstrated very large tunneling magnetoresistance (TMR) values (the higher it is the more useful for application), to achieve even higher P and TMR values. This material system remains largely unexplored and this study should open the way for candidate materials where P approaches 100%, without the interface problems of a half metal ferromagnet. Ferromagnet-insulator interface bonding is crucial in controlling the magnitude of P. We will aim at controlling this bonding for higher P. The possibility to make structures on a nanometer scale with well-tailored materials and interfaces will allow us to create new materials that show suitable properties. In particular, spin-polarized transport through quantum islands gives rise to novel effects such as spin-resonant tunneling, which can greatly enhance the TMR (observed in our laboratory) with the possibility of making spin transistors. The education of students in science through this outreach program will continue in an effective way to meet the national need for enhanced science education. Continuing the tradition, along with training graduate students and postdoctoral researchers, undergraduates and high-school students extensively participate in this research. It will enormously benefit these younger generation by getting trained for future spin based nano technology.
Technical: In this NSF supported individual project a series of investigations are proposed that focus on fundamental properties as well as applied aspects of magnetism, which will benefit both at the basic level as well as for the future spin-based information technology. Spin-polarized transport studies of several novel systems will be done to understand and manipulate the spin polarization (P), necessary for future spin devices. The role of the ferromagnet-insulator interface bonding is crucial in controlling the magnitude of P. Our aim is to control this bonding and explore novel tunnel barriers to achieve higher P, including the exploration of the Co-HfO2 system, predicted to have P=100%. Spin filter tunneling is one of the few ways in which near 100% P (demonstrated in our group in the past), which will be explored for achieving P=100% above LHe temperatures. Based on the electronic structures of the constituent CoB and FeB alloys, we believe it is possible to "tailor" the (Co,Fe)-B band hybridization to achieve even higher P and tunnel magnetoresistance (TMR) values. This material system remains largely unexplored and should open the way for candidate materials with high P, without the interface problems of a half metal ferromagnet. Exploiting dimensionality on a nanoscale, in particular, spin-polarized transport through quantum islands can give rise to novel effects such as spin-resonant tunneling, which can greatly enhance the TMR, as has been observed in our laboratory. Double magnetic tunnel junctions exploiting non-equilibrium spin accumulation and ballistic spin transport will be explored, with potential for novel devices such as spin transistors. As in the past in addition to graduate students, postdoctoral researchers and visiting scientists, undergraduates and high-school students participate in this research program. The education of students in science through this outreach program will continue in an effective way to meet the national need for science education.
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0.915 |
2012 — 2017 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Investigating Two-Dimensional Systems and Surface States Under the Influence of An Internal Exchange Field and Spin-Filtering @ Massachusetts Institute of Technology
****Technical ABstract**** This experimental project aims at investigating two-dimensional systems and surface states such as in topological insulators (TI) and graphene under the influence of an internal exchange field and spin filtering. This investigation is about ferromagnetic order in these Dirac electron systems utilizing the proximity-induced ferromagnetism by magnetic insulator thin film and multilayer stacks, with tailored interfaces. It is theoretically predicted that the spin sub-bands are split and would dramatically alter the spin transport that can be controlled by an electric field. The charge and spin transport behavior in such systems will be studied. This project will also seek Majorana fermions, theoretically predicted to exist in exchange split surface state of p + ip superconducting layer with a strong spin-orbit coupling: nanoscale structures of these, needed, will be investigated. In addition to the rich physics, it is believed that these studies could serve as building blocks towards important future quantum information technologies. Students at all levels (including HS students) and postdocs will participate in this cutting-edge fundamental physics research. They will learn state-of-the-art interfacial characterization techniques at the nanoscale including at the national labs, as well as nanotechnology.
****Non-Technical Abstract**** This project investigates two dimensional novel quantum systems to bring about not only scientific advancement, but also for their potential in future quantum information technologies. The two newly discovered materials systems (graphene and topological insulators) obeying relativistic quantum mechanics have extraordinary properties, and even more so when magnetism is introduced in them. This project will investigate the electrical and magnetic behavior in the latter case, theoretically predicted to show profound change of properties opening up new quantum areas of physics to explore. When this is verified experimentally, as planned in this project, it is expected to serve as building blocks towards important future energy efficient and economically viable quantum devices such as nonvolatile spin based memory and logic devices. Materials characterization tools, including those at the national facilities will be advancing their capabilities. There will be scientific collaboration both within USA and abroad. Students (including high school students) and postdocs participate in this experimental project. They will be trained in the state-of-the-art science at nanoscale including at the national labs, building the future scientific base for advanced science and technology in USA.
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0.915 |
2017 — 2020 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Surface/Interface Phenomena and Topological Order in Emerging Quantum Materials @ Massachusetts Institute of Technology
Non-Technical Abstract: In recent years interest is increasing in a class of emerging new materials called topological insulators (TI) displaying unexpected quantum properties at their surfaces/interfaces. This has led to vast advancement in quantum science, and with potential for future quantum devices that can be energy efficient for information storage and transmission. These new materials can carry current without dissipation and are capable of enhancing the performance in existing technology such as spintronics (used in computer data storage, communication and sensing). Another topology related phenomenon is a new type of quantum state called Majorana bound states (MBS) that can appear in TIs by combining materials with different physical phenomena (topology, superconductivity, magnetism), which may lead to future highly fault-tolerant quantum computing. In this project, students as well as young scientists acquire knowledge and train in many advanced areas, as well as push the frontiers of physics and material science. There is potential to lay the foundation for establishing energy efficient quantum electronics to revolutionize the future information technology. Instruments, patents and knowledge developed during this research would be made available to companies.
Technical Abstract: The demonstration of two-dimensional quantum coherent properties and unexpected stabilization of interfacial ferromagnetism to much higher temperatures in TI by proximity coupling to a ferromagnetic insulator, has prompted the investigation: i) to reach the occurrence of quantum coherent properties in a ferromagnetic TI at a higher temperatures, ii) the quantum behavior of spin polarized chiral current in TIs with proximity induced gap when hybridized with a magnetic insulator, and iii) probe unconventional superconducting pairing, the electron spin polarization and quantum coherence in the edge conduction channel of magnetic TI by tunneling spectroscopy. These goals are achievable based on our extensive previous related multidisciplinary knowledge with thin film heterostructure properties using state of the art molecular beam epitaxial system for film growth and measurement facilities, including atomic level characterization of interfaces utilizing the national facilities. Education and training of students (including high school students summer programs) and young scientists in the areas dictated quantum coherent topology driven phenomena are planned under this program.
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0.915 |
2020 — 2021 |
Lee, Patrick (co-PI) [⬀] Lee, Patrick (co-PI) [⬀] Moodera, Jagadeesh Fu, Liang (co-PI) [⬀] Wei, Peng (co-PI) [⬀] Oliver, William (co-PI) [⬀] |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Nsf Convergence Accelerator Track C: Synergistic Thrusts Towards Practical Topological Quantum Computing @ Massachusetts Institute of Technology
The NSF Convergence Accelerator supports use-inspired, team-based, multidisciplinary efforts that address challenges of national importance and will produce deliverables of value to society in the near future. This project seeks to develop approaches that address issues of decoherence and crosstalk by scalable topological superconductors (TSC). Investigation for achieving realistic large-scale quantum computers is required to advance the field of quantum information science. This project will integrate Majorana zero modes (MZMs) into conventional superconducting qubit architectures to advance their application to quantum computing. By having outreach programs towards K-12 students and research experiences for undergraduates, this project will broaden participation in quantum with a focus on underrepresented minorities. The project will build and establish a cross-sector team that will develop advances in controlling the topological nature of materials to advance quantum computing to deliver fault-tolerant qubits and their quantum interconnects. This project seeks (1) to understand and demonstrate the non-local topological nature of the MZMs by detecting the electron teleportation through a pair of MZMs; (2) to establish the basic elements for measuring the parity state in a teleportation-based T-qubit; (3) to explore flux quantization caused by a supercurrent loop that is mediated by the MZMs and set up the basic flux (or pseudo-spin) measurements of a T-qubit; (4) to identify and plan the Phase II research program, and (5) to build a strong team of academic, governmental lab, and industrial partners. Building on recent developments of a new TSC material platform, this project aims to demonstrate the quantum nature and the non-local topological protection of MZMs in the platform as well as build topological qubits that can be integrated into existing quantum computing circuitry. This may lead to greater functionality in superconducting circuits which can significantly advance topological quantum computing. The project deliverable includes a platform supporting topological qubit that is more robust and more scalable. By establishing a nationwide student exchange program and outreach activities to K-12 students, this project seeks to engage students in quantum research and training to broaden participation.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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0.915 |
2022 — 2026 |
Moodera, Jagadeesh |
N/AActivity Code Description: No activity code was retrieved: click on the grant title for more information |
Correlated Quantum Phenomena At Superconductor/Magnetic Interfaces @ Massachusetts Institute of Technology
Nontechnical abstract: Quantum materials and related technology have been the driving force for giant breakthroughs in physics in the recent decades. For future progress in the field it is essential to understand quantum materials at the atomic level. This research project will focus on combining two quantum systems, namely ferromagnets (FMs) and superconductors (SCs), to enable intriguing scientific inquiries such as the appearance of Majorana pair modes and exotic spin triplet SCs. These topics will be experimentally investigated at cryogenic temperatures using advanced probes, leading to developing practical topological qubits and forming the basis for building a robust, scalable quantum computer. This work will impact quantum materials development, medicine, technology, finance, communication, and national security. The outcome of this multidisciplinary research project also has the potential for leading developments in highly energy-conserving superconducting spintronics, and for advancing quantum information science and engineering. In the process, postdocs and students at all levels would be trained at the forefront of quantum science/technology and material physics. The project will open up ample opportunities for initiating new theoretical and experimental collaborations worldwide, including advanced atomic level interface characterization at national laboratories. This will provide opportunities to the students including high school summer interns for scientific interaction with national and international scientists, and for enriching students' educational and outreach activities, both online and in-person.<br/><br/>Technical Abstract: The project aims at investigating quantum phenomena at atomically resolved hybrid interfaces. Interface driven effects are pivotal in quantum materials study, a focus of this project. This study intends to understand and manipulate correlated effects in hybrid system by combining the quantum systems - ferromagnets (FMs) and superconductors (SCs) at the atomic level. This approach enables the study of signature interfacial exchange interaction, leading to establishing the Majorana bound state pair and their entanglement/teleportation, as well as the spin triplet Cooper pairing in SCs. Following the theoretical prediction, gold (111) surface state with its large spin orbit splitting in conjunction with a large gap SC, is an ideal platform for seeking the simultaneous Majorana pair appearance and understanding the parameters that define the intrinsic behavior/stability. For the triplet pair study the ferromagnetic Ni, EuS or GdN would be proximity-coupled to Ga, Bi or SCs such as Al or NbN, creating model systems for controlled study. To reach the goal, MBE-grown thin film heterostructures, scanning tunneling spectroscopy and high field as well as cryogenic magneto-transport studies would be carried out. The project will lead to a scalable, coherent topological qubit development, and an ideal dissipationless spin polarized source for superconducting spintronics, and the results will impact the field of quantum information science and engineering. Project involves postdocs and students to be trained in multidisciplinary areas at the forefront of quantum science, material physics and nanodevice technology. Opportunities are created for initiating theoretical and experimental collaborations worldwide in interface characterization at national laboratories. Outreach, education and broadening participation efforts in STEM address the needs of undergraduates and high school students, while promoting scientific education.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
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0.915 |