Electronic structure and physical properties of antiferromagnetic Weyl semimetal GdAlSi*

We have studied the electronic structure and physical properties of an antiferromagnetic Weyl semimetal GdAlSi. This compound crystallizes in a LaPtSi-type tetragonal structure with the non-centrosymmetric space group I4₁md. An antiferromagnetic transition is observed at T_N= 32 K due to the ordering of Gd³⁺ moments. In-plane and out of plane magnetic susceptibility measurements confirm a very weak magneto-crystalline anisotropy in this compound. Moreover, in-plane isothermal magnetization shows an unusual hysteresis behavior below T_N, suggesting a possible spiral magnetic order. We observe an exceptionally large anomalous Hall conductivity (AHC) of ∼ 1310 Ω⁻¹cm⁻¹ at 2 K. Interestingly, the anomalous Hall effect persists up to room temperature with a significant value of AHC (∼ 155 Ω⁻¹cm⁻¹). First-principles calculations reveal that GdAlSi hosts multiple Weyl points near the Fermi energy, which is further supported by angle-resolved photoemission spectroscopy (ARPES) measurements. The calculated AHC from Berry curvature associated with the Weyl nodes is close to the experimental value of AHC.