Current state-of-the-art computational approaches rely on the von Neumann architecture with several layers of memory. In data-intensive computation, i.e. the vast majority of computing tasks, the power consumption bottle-neck is found in memory access and storage. More specifically, almost all power is lost in the duplication of data from one layer of storage (cache/register) to another layer of storage. Consequently, to significantly improve over the current state-of-the-art, a non-volatile memory device that can be fabricated reliably with high-density (i.e. stacked/3D memory) is required. More specifically, a universal memory with following characteristics is needed: 1) non-volatility, 2) no readout circuitry with controller, 3) high-density, 4) low power-consumption. To simultaneously meet these 4 requirements, spin-based memories are the most promising.
A first big challenge however is that manipulating spin at the nanoscale efficiently mandates an entirely different approach compared to “conventional” magnetic approaches (e.g. using giant magnetoresistance). Conventional magnetic approaches rely on the magnetic (i.e. Lorentz) force which becomes exceedingly small (~10-5 eV) when only a few spins/electrons interact with each other. Thus, such nanoscale conventional magnetic approaches can never operate without readout circuitry. On the other hand, performing spin-manipulation based on spin-orbit coupling becomes increasingly efficient as dimensions are reduced. A second challenge consists of the fabrication of nanoscale ferromagnets with a Curie temperature above room temperature. Here, the recent discovery of intrinsic ferromagnetism in two-dimensional van der Waals crystals is very encouraging. Ultimately, combining efficient nanoscale spin-manipulation with nanoscale ferromagnets opens the route towards magnetism-based memory devices that switch on the pi
cosecond scale while consuming only a few attojoules to perform a switching operation.
In the project, the student will study the theoretical limits of magnetism-based memory devices. In a first task, the student will study switching of ferromagnets using spin-orbit coupling rather than using a conventional magnetic switching mechanism. In a second task, the student will develop a theory of ferromagnetism and compute Curie temperatures for nanoscale materials, e.g. a transition-metal dichalcogenides (TMD) doped with iron.
This topic is suited for students interested in studying many-body condensed matter physics in nanoscale materials using theoretical methods. The research will consist of using existing codes to study materials, developing new theoretical approaches, and writing the appropriate code to study electronic and ferromagnetic properties of nanoscale materials. The student can use existing capabilities of first principles calculations and in-house quantum transport codes at the University of Texas at Dallas (UT Dallas) and imec/KU Leuven.
The research will be conducted jointly between imec/KU Leuven, Belgium and the department of Materials Science at UT Dallas. Both are world-renowned institutions in the field of nanoelectronics research. Upon completion of the PhD program, the student will be awarded a PhD degree from KU Leuven and UT Dallas. In the first stages of the PhD, research will mainly take place at UT Dallas where the student will take up coursework (tuition will be paid by UT Dallas).
Required background: condensed matter physics, quantum mechanics, computational nano-electronics
Type of work: The research will consist of using existing codes to study materials, developing new theoretical approaches, and writing the appropriate code to study electronic properties in new materials and devices.
Supervisors: Bart Soree (imec/KU Leuven), William Vandenberghe (UT Dallas)
Daily advisors: Bart Soree (imec/KU Leuven), William Vandenberghe (UT Dallas)
The reference code for this PhD position is STS1712-08. Mention this reference code on your application form.