Study of Multiferroic Tunnel Junctions

多铁性隧道结的研究

• 批准号: 0907604
• 负责人: Qi Li
• 金额: $ 23万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0907604&HistoricalAwards=false
• 关键词: Study; Multiferroic; Tunnel; Junctions

Technical AbstractThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Multiferroic tunnel junction refers to a ferromagnetic tunnel junction using a ferroelectric insulator barrier. Theoretical calculations have shown that the ferroelectric polarization reversal will result in resistance switching behavior in a tunnel junction. Furthermore, the interplay between the ferroelectric and ferromagnetic layers can affect the electric polarization of the barrier, the electronic structures and the magnetic properties at the interface, and the spin polarization of the tunneling current. This type of junctions can thus display new functionalities, such as quaternary or octal logic state, which can be encoded by both magnetic and electric fields. It can also open up new ways to potentially control spin polarization electrically. However, to preserve ferroelectricity in a nanometer thick ferroelectric layer sandwiched between two ferromagnetic layers is extremely challenging and reliable multiferroic junctions have not been achieved previously. This individual investigator award supports a research plan to fabricate and systematically study the multiferroic tunnel junctions in manganite/Ba1-xSrxTiO3/manganite and manganite/Ba1-xSrxTiO3/Co structures. The objective of the project is to first establish the behaviors of such junctions under electric and magnetic fields, and then to systematically study the manipulation of the different states by both electric and magnetic fields. The project will provide both graduate and undergraduate students, including women and underrepresented minorities, with a stimulating environment for interdisciplinary experience in physics, materials sciences, and device fabrication and testing. Non- Technical AbstractThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5). Recent advances in magnetic tunnel junctions have made it possible to use these devices in computer read head, magnetic sensors, and non-volatile magnetic random access memories. A tunnel junction consists of two metal layers and a nanometer thick insulator layer or barrier in between. It was predicted theoretically that by using a very thin ferroelectric insulator--a material with a spontaneous charge polarization which can be switched by an electrical voltage--as the barrier, new functionalities can be achieved. For example, it can display quaternary logic states which can be encoded by both magnetic and electric fields, instead of the binary states in the current magnetic tunnel junctions. This could be very important for quantum information processing. The strong interaction between the ferromagnetic layer and the ferroelectric layer can also lead to control of the spin polarization electrically, which is a critical advance in achieving functional spintronic devices, a new device concept that relies on the spin polarized transport instead of the conventional electron transport. However, to achieve charge polarization in a nanometer thick material is extremely challenging and such junctions have not been made previously. This award supports a research plan to fabricate and systematically study several such junction structures using manganite as the electrode and Barium Strontium titanate as an insulator. The goal of the project is to first fabricate the junctions, and then to systematically study the junction properties and how to manipulate the different states by using electrical and magnetic fields. The project will provide both graduate and undergraduate students, including women and underrepresented minorities, with a stimulating environment for interdisciplinary experience in physics, materials sciences, and device fabrication and testing.

技术摘要这一奖项是根据2009年《美国复苏与再投资法》（公法111-5）资助的。多型隧道连接是指使用铁电绝缘体屏障的铁磁隧道连接。理论计算表明，铁电偏振反转将导致隧道连接处的电阻切换行为。此外，铁电和铁磁层之间的相互作用可能会影响势力处的屏障，电子结构和磁性的电化，以及隧道电流的自旋极化。因此，这种类型的连接可以显示出新的功能，例如第四纪或八达逻辑状态，可以通过磁场和电场编码。它还可以打开潜在地控制自旋极化的新方法。然而，在两个铁磁层之间夹在纳米厚的铁电层中的铁电性是极具挑战性的，并且以前尚未实现可靠的多效连接。该个人研究者奖支持一项研究计划，该计划旨在制造和系统地研究锰矿/b​​a1-xsrxtio3/锰矿和锰/ba1-xsrxtio3/co结构中的多效隧道连接。该项目的目的是首先在电场和磁场下建立此类连接的行为，然后通过电场和磁场系统地研究对不同状态的操纵。该项目将为包括妇女和代表性不足的少数民族在内的研究生和本科生提供刺激性的环境，以实现物理，材料科学以及设备制造和测试的跨学科经验。非技术摘要奖是根据2009年《美国复苏与再投资法》（公法111-5）资助的。磁性隧道连接的最新进展使得在计算机读取头，磁性传感器和非挥发性磁随机访问记忆中使用这些设备成为可能。隧道连接包括两个金属层和纳米厚的绝缘体层或障碍物。从理论上讲，通过使用非常薄的铁电绝缘子 - 一种具有自发电荷极化的材料，可以通过电压切换，就像屏障一样，可以实现新的功能。例如，它可以显示可以通过磁场和电场编码的第四纪逻辑状态，而不是当前磁性隧道连接中的二元状态。这对于量子信息处理可能非常重要。铁磁层和铁电层之间的强相互作用也可以导致电气控制自旋极化，这是实现功能性自旋设备的关键进步，这是一种依赖于自旋极化传输而不是常规电子传输的新设备概念。但是，要在纳米厚的材料中实现电荷极化极具挑战性，此类交界以前尚未实现。该奖项支持一项研究计划，以使用锰矿和钛钛矿作为绝缘子来制造和系统地研究几种此类连接结构。 该项目的目的是首先制定交界处，然后系统地研究连接特性以及如何使用电气和磁场来操纵不同状态。该项目将为包括妇女和代表性不足的少数民族在内的研究生和本科生提供刺激性的环境，以实现物理，材料科学以及设备制造和测试的跨学科经验。