Complex magnetic order and magnetotransport in a Eu-based square net compound

Rare earth intermetallics often display complex magnetic and transport properties, owing to the interplay between different energy scales such as Rudeman-Kittel-Kashuya-Yoshida (RKKY) interactions and crystal electric field effects (CEF). However, Europium ions have a half full 4f electronic shell, which means that the CEF should be absent in such compounds, and therefore the magnetic order is expected to be a simple collinear antiferro- or ferro-magnetic ground state. Our group has recently shown that a series of Eu-based intermetallics with square net crystal structure, Eu(Ga,Al)₄, have complex magnetic and topological properties, even in the absence of CEF effects, prompting the need for finding the origin of the competing interactions other than CEF anisotropy. In this talk, I will discuss our recent synthesis of new high quality single crystals of a Eu-based square net compound. This material is a candidate for magnetic topological systems. The temperature- and field-dependent magnetization and resistivity measurements reveal at least three magnetic phase transitions below 10 K, and relatively large magnetoresistance MR ~ 20% up to 9 T. I will discuss the detailed H-T phase diagram in this compound, and the possible origin of the anisotropy that leads to the apparent non-collinear magnetic order, responsible for the multiple magnetic transitions.