The defense session for a dissertation entitled "Density Functional Theory Studies of 2D Materials for Spintronics" submitted by Ms. Maedeh Rassekh in partial fulfillment of the requirements for the degree of Ph.D. in physics was held on September.21, 2022 at 6:30 pm (Tehran time) in the faculty of science, University of Guilan (UG) and simultaneously online through Skype at Universidad Autónoma de Madrid (UAM). Prof. Saber Farjami Shayesteh (UG) and Prof. Juan José Palacios Burgos (Universidad Autónoma de Madrid) jointly supervised this dissertation. After due deliberation, the examination committee (Dr. Saeed Mahdavifar and Dr. Hanif  Hadipour from UG; Dr. Ali Tavana from University of Mohaghegh Ardabili; Dr. Linda Angela Zotti from UAM and Dr. Daniel Gosálbez Martínez from Universidad de Alicante) reached the decision that the dissertation is approved with an excellent grade.

In this dissertation, an attempt has been made to explore the properties of some promising two-dimensional materials for spintronics applications. The key achievements of the projects presented in this dissertation are:

• A strong enhancement of the Curie temperature by full hydrogenation of a CrI3 monolayer which is known as the first truly 2D magnet. At temperatures higher than the Curie temperature, magnetic materials lose their magnetism. The higher the Curie temperature of the magnets, the more realistic temperature conditions are possible to use these materials.
• Presenting a density functional theory-based quantum transport methodology to address charge-spin interconversion in two-dimensional materials with spin-orbit coupling. Charge and spin are two different and important properties of electrons. Charge and spin currents can be generated by each other. For example, we can generate spin currents or spin accumulations by a charge current. Interconversion between charge and spin currents, which have very important applications in spintronics, are possible in materials with certain characteristics and through certain mechanisms.
• Characterization of the electronic properties of mechanically exfoliated FL antimonene of different thicknesses (~ 2 - 40 nm), in collaboration with an experimental group in Madrid. Our results suggest that topologically protected surface states (TPSS) should play a key role in the electronic properties of FL antimonene.

The International Scientific Cooperation Office (ISCO) of UG, ISCO congratulations for making it to this end after hard work and astute determination to succeed. We wish her the best in her future endeavors.

Footnote:

For many years, scientists used to think that one and two-dimensional materials cannot exist at finite temperatures due to thermodynamic instability. But in 2004, material science achieved great success. Novoselov and Geim isolated the first two-dimensional material, Graphene, through the Scotch tape exfoliation of graphite. This achievement was so important that the Nobel Prize in 2010 was awarded jointly to these two scientists.

Since the discovery of graphene, the family of 2D materials is gradually expanding. 2D materials are being explored for their fascinating properties and a wide range of applications in electronics, spintronics, plasmonics, photodetectors, sensing, ultrafast lasers, batteries, supercapacitors, thermoelectrics, and energy storage, just to name a few.