Observation of antiferromagnetism in Nickel monosilicide*

Over the past decades, discoveries of unconventional properties of antiferromagnets, such as in Mn3Si, FeGe, etc., have made them very interesting candidates for spin-based technologies and applications. Nickel monosilicide, an important intermetallic system, significantly used as interconnects in nanoelectronic devices, has never been reported to have magnetic order despite the presence of Ni. Non-trivial temperature dependences of both nuclear positions as well as odd reciprocal lattice positions have been observed from elastic neutron diffraction measurements on our home-grown NiSi sample, indicating the existence of an uncompensated antiferromagnetic order with an onset temperature of 700K, in the system. On applying magnetic field perpendicular to the direction of the non-compensated moments, hysteresis behavior is observed with a one-step switching characteristic at a very small critical field of H ~ 900 Oe. This abrupt transition observed both at T = 350K and T =20K, accounts for switching between two distinct minimum energy ferromagnetic spin configurations. The evidence of the uncompensated antiferromagnetism is also observed in the non-zero hall resistance at H = 0T, along with magneto-electronic hysteresis for both longitudinal and Hall resistances at high temperatures indicating a complex behavior that has been explored for the very first time in this system.