Sophia Chen of MRS Bulletin interviews Jason Azoulay of the University of Southern Mississippi about his conjugated polymer semiconductor, a promising candidate for technologies that integrate both conventional electronics and spintronics. Read the article in Science Advances.
SOPHIA CHEN: Conventional electronics like your smartphone or computer use the voltage and current of electrons in a material to encode and transmit information. Spintronics aims to exploit the quantum spin of those electrons as an additional signal. Jason Azoulay of the University of Southern Mississippi, develops materials that might be useful for spintronics combined with conventional electronics.
JASON AZOULAY: People are looking at controlling electron correlations and spin and magnetism for emerging types of technologies. There’s a wide variety of technologies, whether it’s something as far off as quantum computing or new types of magnetic materials, or even multifunctional activities where you effectively combine things like spin degrees of freedom with charge transport or some type of optoelectronic functionality.
SC: For spintronics, materials have to exhibit strong magnetism known as a high-spin state. On the microscopic scale, this means that the electrons involved in chemical bonds in the material need to have their spins aligned in the same direction. It has been difficult to make organic high-spin materials that are stable at room temperature. Azoulay and his colleagues have made such a material.
JA: We’ve tested it for a while, and it’s a rock. It’s very stable.
SC: The material is a type of macromolecule known as a conjugated polymer, meaning that its constituent molecules are stitched together by a backbone of shared electrons. In the material’s ground state, these electrons align in pairs, thereby collectively creating the desired “high spin state.”
JA: The best way to think about it is that we made a polymer organic magnet.
SC: The material, which looks like a black powder, behaves like a semiconductor. The flow of these electrons through the material can be turned on and off according to its bandgap energy. In addition, the polymer’s bandgap energy is easy to tune. It consists of alternating molecules of cyclopentadithiophene and thiadiazoloquinoxaline, which are an electron donor and acceptor, respectively. Because of this tunable bandgap and its high spin state, the material is a promising candidate for technologies that integrate both conventional electronics and spintronics. The researchers found that a minimum of 13 donor-acceptor pairs were required in order to create the electron interactions that produce the high-spin state.
JA: We’re working on next generation versions of this material. The questions are, can we increase the conductivity? Can we increase the magnetic properties? Can we control the electronic topology? Can we control the properties of the spins. Another fun aspect of it as well, how are these going to interact with electromagnetic fields or stimuli or light. We’re studying their properties because they’re fundamentally new materials.