Year: 2023
Type: article
Abstract: Magnetotransport measurements of the centrosymmetric square net ${{\mathrm{Eu}(\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x})}_{4}$ compounds reveal evidence of both reciprocal- and real-space topology. For compositions $0.50\ensuremath{\le}x\ensuremath{\le}0.90$, several intermediate field phases are found by magnetization measurements when $H\ensuremath{\parallel}c$, where a maximum in the topological Hall effect is observed, pointing to the existence of topological (real-space topology) or noncoplanar spin textures. For $0.25\ensuremath{\le}x\ensuremath{\le}0.39$, magnetization measurements reveal an intermediate field state, but no transition is visible in the Hall measurements. For $x=0.15$, only one magnetic transition occurs below the N\'eel temperature ${T}_{N}$, and no intermediate field spin reorientations are observed. The Hall effect varies smoothly before the spin-polarized (SP) state. However, in the SP state, Hall measurements reveal a large anomalous Hall effect (AHE) for all compositions, a consequence of reciprocal-space topology. Density functional theory calculations in the paramagnetic state indeed reveal a Dirac point that lies very near the Fermi energy, which is expected to split into Weyl nodes in the SP state, thereby explaining the observed AHE. These results suggest the ${{\mathrm{Eu}(\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x})}_{4}$ family is a rare material platform where real- and reciprocal-space topology exist in a single material platform.
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W4386325201