Heteromolecular Interface Design for Better Multiferroic Molecular Spintronics

在美国和世界其他地方，对计算机内存的需求不断增长。不幸的是，与制造和使用计算机内存相关的能源成本正在以一种最终不可持续的速度增长。按照目前的增长速度，如果技术不发生变化，在20年内，存储器的能源成本将超过世界能源产量。避免危机所需要的是新技术，这种新技术既能满足日益增长的对更多计算机内存的需求，又能消耗更少的能源，占用更少的空间，而且既可靠又便宜。这项研究的主要目标是开发一种高度稳定的存储设备，其尺寸比人类头发的宽度小10000，基于一类可以用电控制状态的分子。这些装置将由可以用小电压切换的分子制成。其优点是，这将是高质量的存储器，速度快，耗电量少，制造成本低，但非常稳定。这种存储技术的发展将对各种应用产生重大影响，包括帮助计算机更快、更高效地运行，并可能解决美国各地出现的数据中心带来的日益增长的能源消耗问题。如果这些设备具有竞争力并易于实施，必须开发新的理解。这个项目的研究和教育活动是紧密交织在一起的。研究活动将为研究生，本科生，甚至K-12学生提供宝贵的学习经验。来自STEM领域代表性不足群体的学生也是重点关注对象。技术描述本研究的重点是更好地理解如何设计基于分子的电压控制器件，其性能与硅半导体器件的性能竞争甚至超过硅半导体器件的性能。通过研究如何利用局域电场来控制分子的磁性和进一步操纵分子系统的电导，为分子电子学提供了新的见解。分子的量子态不仅可以通过光谱组合来表征，而且可以通过表征原型分子晶体管来更好地理解关键物理。铁电分子（具有可切换电偶极子的材料）和自旋交叉分子膜（可以从磁性切换到非磁性的分子）之间的界面似乎是关键，但如果要“通过设计”制造更好的设备，则需要了解该界面上的相互作用。结合分子体系将采用多种光谱技术进行表征，并通过研究测试原型器件来确定自旋态、电偶极子，以及研究磁矩与电偶极子的关系。此外，该研究小组认为，对光的颜色和偏振敏感的分子光电晶体管的创造是可以实现的。关键目标是：(1)确定为什么电压控制开关不简单地局限于接口。(2)确定自旋态开关的能量势垒和这些能量势垒的来源。(3)确定温度变化对分子自旋态的影响。(4)制作光晶体管，并探测光载流子的特性。(5)研究高自旋态和低自旋态的分子电子学细节。最后一个目标是将分子的量子态与晶体管的特性联系起来。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical DescriptionThere is a growing demand for computer memory across the U.S and elsewhere in the world. Unfortunately, the energy cost associated with the fabrication and use of computer memory is growing at a rate that is ultimately unsustainable. At the current growth rates, in two decades the energy cost for memory will exceed the world's energy production if there is no change in technology. What is needed to avert a crisis are new technologies that support the growing need for more computer memory, but use far less energy, occupies less space and is both reliable and inexpensive. The main goal of this research is to develop a highly stable memory device, with a size that is 10,000 smaller than the width of a human hair, based on a class of molecules whose state can be electrically controlled. These devices will be made from molecules that can be switched with a small voltage. The advantage is that this will be high quality memory that is fast, requires little power, and is inexpensive to make yet very robust. The development of this memory technology will have a significant impact on various applications, including helping computers run faster and more efficiently and may address the growing problem of the increasing energy consumption posed by data centers that are appearing across the U.S. New understanding must be developed if these devices are to be competitive and easily implemented. The research and education activities of this project are closely intertwined. The research activities will provide valuable learning experiences for graduate students, undergraduate students, and even K-12 students. Students from underrepresented groups in STEM fields are also a key focus.Technical DescriptionThe focus of this research is on developing a better understanding of how to design molecular based voltage-controlled devices whose performance competes or even surpasses the performance of silicon semiconductor devices. By studying how to use a local electric field to control the molecular magnetic properties and further manipulate the conductance of the molecular system new insights in molecular electronics are developed. Not only can the quantum states of the molecule be characterized by a combination of spectroscopies, but a better understanding of the key physics can be developed by characterizing prototype molecular transistors. The interface between a molecular ferroelectric, a material with a switchable electric dipole, and a spin crossover molecular film, molecules which can switch from magnetic to non-magnetic seems key, but the interactions in play at this interface need to be understood if better devices are to be fabricated 'by design'. The combination of molecular systems will be characterized by a variety of spectroscopic techniques and through the study of test prototype devices to determine spin state, electric dipole, as well as to investigate the relationship between magnetic moment and electric dipole. Additionally, this research team believes that the creation of a molecular phototransistor sensitive to light color and polarization is realizable. The key goals are: (1) To determine why voltage-controlled switching is not simply restricted to the interface. (2) To identify the energy barriers to spin state switching and the origin of these energy barriers. (3) To ascertain the effects of changing temperatures on the molecular spin state. (4) To make a phototransistor and probe the characteristics of the photocarriers. (5) To investigate the details of the molecular electronics for both the high and low spin states. This last goal connects the quantum state of the molecule with the transistor properties.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.