Thermal Transport in Ferroelectric Metal chalcogenophosphates

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

Ferroic Metal Thio/Seleno Phosphates (MTPs) are ultra-thin materials with unique properties that make them promising for future technologies such as smart memory devices and advanced computing. MTPs are one of the rare materials that exhibit stable inherent ferroelectricity and antiferromagnetism, even at single atomic layer or few-layer thicknesses. Unlocking their potential requires understanding how their structure and electrical properties depend on thickness and temperature, and how they handle thermal transport and responses (how they generate, absorb, and release heat). In many applications, it is also important to know how these materials respond to external stimuli such as electric and magnetic fields and pressure. Additionally, understanding how heat is absorbed or released during a phase transition in these materials is useful for optimizing their energetic performance. This research aims to develop a comprehensive framework to study MTPs' thermal transport properties focusing on effects of temperature, material properties, and external stimuli. Graduate and undergraduate students will be mentored leveraging collaboration between the University of Virginia and the Air Force Research Laboratory, contributing to workforce development in academia and Air Force. The project will also engage the broader community through K-12 workshops and a summer program for high school students. MTPs are moderate- to wide-bandgap semiconductors with a host of diverse ferroic properties making them strong candidates for gate-tunable, switchable memristors and non-volatile memory devices. These materials have the potential to revolutionize next-generation nanoelectronics, particularly in the fields of spintronics and neuromorphic computing. Furthermore, many MTPs exhibit incipient, or even finite ionic conductivity at moderate temperatures. This, in turn, leads to the possibility of structural phase transitions and intriguing new thermochemistry. Over the past decade, significant attention has been focused on this class of materials, particularly in identifying their magnetic, electric, and structural phases. However, their thermal transport properties—and the effects of temperature, thickness, intercalation, doping, and external stimuli such as pressure, electric fields, and magnetic fields—have rarely been studied. The vision of this proposal is to establish a comprehensive theoretical and experimental framework for studying phonons, heat generation, and heat transfer—primarily via phonons and ions- in ferroelectric MTPs, including ferrielectric (e.g., CuInP2S6), antiferroelectric (e.g., CuBiP2 Se6), and multiferroic (e.g., CuCrP2S6 ) materials. Leveraging collaboration between the University of Virginia and the Air Force, the team will grow ferroelectric MTP single crystals and characterize their crystal structure, electronic and phononic dispersion, ferroelectric and magnetic domains and phases, as well as their thermal, and where relevant, electrical and magnetic transport properties under external stimuli. A fundamental understanding will enable the dynamic tuning of thermal properties using strain, electric and magnetic fields. 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.