Probing magnetism of a 2D magnet with Pt through magnetoresistance*

2D magnetic materials have lately attracted tremendous research interest in condensed matter physics. Very interestingly, chromium triiodide (CrI₃), an insulating member of the 2D magnet family, has been discovered to possess antiferromagnetic coupling between layers, as demonstrated by magneto-optic Kerr effect and tunneling measurements in ultra-thin samples. In our work, we place a CrI₃ flake in direct contact with a pre-patterned Pt Hall bar which serves as a sensing layer. We observe a sharp increase in magnetoresistance (MR) at H(along c-axis) ~ 2T. This feature coincides with a major magnetization switching previously reported in CrI₃ flakes with thickness above 3 layers. Temperature and field direction dependent MR measurements have also been conducted and the results reveal further information about the nature of the magnetic interactions. Our approach offers a unique platform to study magnetic ordering in CrI₃ and other highly resistive 2D magnetic materials through electrical transport measurements. It also provides an interesting perspective for studying the intriguing physics of exchange proximity coupling and spin current effect at 2D van der Waals interfaces.