, a tuneable quantum magnet at room temperatures*

The kagome magnet TbMn₆Sn₆ exhibits a near-perfect structure for exploring topological Chern physics, which features a Mn kagome plane and a nearby perpendicular magnetic anisotropic Tb layer below 310 K (the spontaneous spin reorientation transition “point”, T_SR). Scanning tunnelling microscopy/spectroscopy has confirmed the presence of Chern gap and chiral boundary states within TbMn₆Sn₆. Additionally, the Berry curvature, generated by the gapped Dirac cone, contributes to intrinsic effects like the giant anomalous Hall effect and the giant anomalous Nernst effect, among others. In this study, we present a giant nonlinear Hall effect in TbMn₆Sn₆ occurring near T_SR, which includs the room temperature. The SR transition allows manipulation of the orientation of Tb and Mn moments between the c-axis and the a-axis by applying a small magnetic field. We have employed focused ion beam lithography to fabricate micron-sized Hall-bar devices with  current running along either the a-axis or the c-axis. Our temperature-, magnetic-field-, and electronic-current-depend investigations emphasize that the quantum magnet TbMn₆Sn₆ can be precisely tuned at room temperature, and thus holds significant potential for high-efficiency spintronic applications.