Heteromolecular Interface Design for Better Multiferroic Molecular Spintronics

Non-technical Description

There 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 Description

The 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.