169th MSL Lecture (Prof. Aftab Alam) 12/7

Time and Date: December 7, 2023, 13:00 – 15:00
Place: 1F Meeting Room R3 Building, Suzukakedai campus or Online (Zoom)　　
Online Remarks: Registration to participate online.
Language: English

"GdAlSi: A potential candidate for altermagnetic topological Weyl semimetal"

Speaker:　Prof. Aftab Alam
(Department of Physics, Indian Institute of Technology Bombay)

Abstract:
Spintronics has emerged as a viable alternative to conventional electronics in the past few decades. On one hand, discovery of topological phases of matter with protected spin-polarized states have shown promising applications while on the other hand, new magnetic materials have shown in- triguing phases of collinear antiferromagnets with unconventional spin-splitters. In this work, we report the co-existence of these two interesting phases in a single material: GdAlSi. GdAlSi crys- tallizes in a body-centered tetragonal structure with a non-centrosymmetric space group I41md (109). The magnetization data indicates antiferromagnetic (AFM) ordering with an ordering temperature (TN) 32 K. Ab-initio calculations show GdAlSi to be a collinear antiferromagnetic Weyl semimetal (WSM) with an unconventional momentum-dependent spin splitting (also nomenclature as altermagnetism). Fermi arcs, a characteristic feature of WSMs, have been subsequently observed in angle-resolved photoemission spectroscopy (ARPES) measurements performed on GdAlSi single crystals. Electric and magnetic multipole analysis gives a deeper insight into the symmetry mediated momentumdependent spin splitting which has a strictly non-relativistic origin. To the best of our knowledge, such coexistence of unconventional AFM order and non-trivial topology is unprecedented and has never been observed before in any material which makes GdAlSi a wonder material. Finally, we propose a device which can leverage this unique coexistence leading to practical and efficient topotronic application

• MSL: 169th MSL Lecture (Prof. Aftab Alam)