Giant magnetoresistance and topological Hall effect in the EuGa<sub>4</sub> antiferromagnet
H Zhang, Xiaoyan Zhu, Yang Xu, Dariusz Jakub Gawryluk, Weiwei Xie, Sailong Ju, M. Shi, T. Shiroka, Qingfeng Zhan, E. Pomjakushina, Tian Shang
Abstract
Abstract We report on systematic temperature- and magnetic field-dependent studies of the EuGa 4 binary compound, which crystallizes in a centrosymmetric tetragonal BaAl 4 -type structure with space group I 4/ mmm . The electronic properties of EuGa 4 single crystals, with an antiferromagnetic (AFM) transition at T N ∼ 16.4 K, were characterized via electrical resistivity and magnetization measurements. A giant nonsaturating magnetoresistance was observed at low temperatures, reaching <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo>∼</mml:mo> <mml:mn>7</mml:mn> <mml:mo>×</mml:mo> <mml:mn>1</mml:mn> <mml:msup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> </mml:msup> </mml:math> % at 2 K in a magnetic field of 9 T. In the AFM state, EuGa 4 undergoes a series of metamagnetic transitions in an applied magnetic field, clearly manifested in its field-dependent electrical resistivity. Below T N , in the ∼4–7 T field range, we observe also a clear hump-like anomaly in the Hall resistivity which is part of the anomalous Hall resistivity. We attribute such a hump-like feature to the topological Hall effect, usually occurring in noncentrosymmetric materials known to host topological spin textures (as e.g., magnetic skyrmions). Therefore, the family of materials with a tetragonal BaAl 4 -type structure, to which EuGa 4 and EuAl 4 belong, seems to comprise suitable candidates on which one can study the interplay among correlated-electron phenomena (such as charge-density wave or exotic magnetism) with topological spin textures and topologically nontrivial bands.