Spin waves in doped graphene

Spin-waves have been studied to a great extent in solids and two-dimensional electron gases. These phenomena have garnered much interest in developing new kinds of devices for information processing and transmission. A major feature of these devices is that they would consume much less power than traditional electronics as there are no charge currents. In spin-polarized itinerant electron systems, collective spin-wave modes arise from dynamical exchange and correlation (xc) effects. We here consider spin waves in doped paramagnetic graphene with adjustable Zeeman-type band splitting. The spin waves are described using time-dependent spin-density-functional response theory, treating dynamical xc effects within the Slater and Singwi-Tosi-Land-Sjolander approximations. We obtain spin-wave dispersions and spin stiffnesses as a function of doping and spin polarization, and discuss prospects for their experimental observation. Beyond our results for graphene, the methods developed in this work have the potential to be applied to other materials, e.g. silicene, stanene, MoS₂, or other members of the so-called "beyond-graphene" family, for which the electron gas is not a good reference system. The ubiquitous local density approximation (LDA), generalized gradient approximation (GGA), and all of their descendants are examples that implicitly use the electron gas reference system. Orbital based approximations such as Slater and Singwi-Tosi-Land-Sjolander provide an alternative that use no reference system. Being built from orbitals, these approximations are inherently system specific, but we have developed techniques to aid in their construction.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Physics and astronomy (MU)

Grantor dc:publisher

University of Missouri--Columbia

Year dc:date.issued

2021

Author dc:creator

• Anderson, Matthew J.

Advisor dc:contributor.advisor

• Ulrich, Carsten

Language dc:language.iso

eng, English

DOI

https://doi.org/10.32469/10355/90151

OAI identifier oai:identifier

oai:mospace.umsystem.edu:10355/90151