Colossal Room Temperature Nonreciprocal Hall effect*

Nonreciprocal charge transport in quantum materials has attracted enormous interest since it holds many prospective applications such as photodetection. The nonreciprocal transport reported to date occurs along the longitudinal direction with the nonreciprocal resistance limited to a few percent of the ohmic resistance. In this talk, we report a room-temperature transverse nonreciprocal transport phenomenon with divergent nonreciprocity – colossal nonreciprocal Hall effect (NRHE). This is revealed in DC transport measurements on the microscale Hall devices made of the Pt wires deposited by focused ion beam (FIB) on Si substrates. When a DC current is applied along the x-axis of the devices (I_x), it generates a voltage along the y-axis (V_y) near room temperature, with V_y∝(I_x)^2. The transverse resistance, which shows a sign reversal upon switching the current direction, results from a colossal extrinsic nonlinear Hall effect (NLHE) induced by geometric asymmetric scattering of textured Pt nanoparticles. Such a NLHE generated in FIB deposited Pt can be transmitted to a metal with FIB deposited Pt electrodes via a proximity effect. These findings pave the way for exploring NRHE’s applications in terahertz communication, imaging, and energy harvesting.