remanence in Dzyaloshinskii-Moriya Interaction driven Weak ferromagnets

We observe that a number of Dzyaloshinskii-Moriya Interaction (DMI) driven weak ferromagnets (WFMs) including α-Fe₂O₃, MnCO₃ and NiCO₃ exhibit two distinct time scale in the magnetization relaxation process as explored through SQUID magnetometry. One of the time scales of relaxation is short and, therefore, leads to a quick decay while the other is ultraslow leading to the observation of a time-stable remanence [1]. Furthermore, the time-stable remanence also varies with the strength of the magnetic field in a very unexpected way. We propose that these unique features of remanence explored in systems of different length scales covering bulk single-crystal to nanocrystallites can be taken as the footprint of weak ferromagnetism. We also find that this time-stable remanence which is intrinsic to WFMs can considerably be tunable by nano scaling as explored in the room temperature WFM α-Fe₂O₃ synthesized in various shapes, size, and morphologies. Corroborated by the synchrotron XRD measurements the study has provided us crucial insights to optimize the magnitude of time-stable remanence in α-Fe₂O₃ which has a prominent role in antiferromagnetic spintronics [2].

[1]. N. Pattanayak et al. Phys. Rev. B, 2017, 96, 104422
[2]. N. Pattanayak et al. J. Phys. Condens. Matter, 2019, 31, 365802.