LDRD Seminar Series: ‘Magnetism, Topology and Their Interplay in Inversion Asymmetric Crystals’
Argonne Scholar-Director’s Fellow Nirmal J. Ghimire (MSD) will discuss his Laboratory-Directed Research and Development (LDRD) sponsored work at the LDRD Seminar Series presentation Tuesday, Dec. 5, 2017. “Magnetism, Topology and Their Interplay in Inversion Asymmetric Crystals” begins at 12:30 p.m. in the Building 203 Auditorium. All are welcome to attend.
Symmetry characterizes the structure of crystalline materials and influences their physical properties. It has recently been realized that exotic magnetic textures and novel electronic states are stabilized when inversion symmetry in a crystal is broken. In this talk Ghimire will discuss the formation of a non-linear magnetic structure called a “chiral magnetic soliton” and a novel topological state — Weyl semimetal in the inversion asymmetric crystals and present their properties with specific examples of Cr1/3NbS2 and NbAs, respectively. He will then talk about a new approach of combining these magnetic and topological features in a single material and present the anomalous Hall effect in a non-centrosymmetric antiferromagnet CoNb3S6 which was discovered in pursuit of this direction.
Nirmal Ghimire is a director’s postdoctoral fellow in the Materials Science Division. He obtained a Ph.D. in physics from University of Tennessee in 2013, where he carried out research on noncentrosymmetric magnets, 2D semiconductors and permanent magnets for vehicle technology mostly at the nearby Oak Ridge National Laboratory. He then moved to Los Alamos National Lab as a postdoc where he worked on heavy fermion and topological materials. While at Los Alamos, Ghimire won a prestigious Seaborg fellowship to study the emergent properties in Actinide compounds before joining Argonne as a Director’s Fellow in the Materials Science Division.
Ghimire uses solid state chemistry and metallurgical synthesis techniques to develop physical platforms for investigating topological properties, magnetism and their interactions in solids. His work primarily involves materials design, crystal growth and characterization with an emphasis on transport property studies. His effort in materials synthesis and characterization has resulted in 37 publications that are cited more than 2900 times (Google scholar citations) and a US patent.