Coherent manipulation of laser-induced spin reorientation dynamics in ErFeO3 with intense THz magnetic nearfields

Terahertz (THz) magnetic field directly interacts with spin systems through Zeeman torque, enabling selective excitation of magnetic order dynamics. Here we demonstrate coherent THz-control of macroscopic magnetization in ErFeO3 using metamaterial-enhanced magnetic nearfields. We fluctuated initial process of laser-induced spin reorientation transition to modify the coherent path of phase transition, resulting in macroscopically magnetized domain. We found that the direction of created magnetization is determined either by the instantaneous phase of spin precession or of applied THz magnetic field. Our results extend the potential applicability of THz magnetic fields to ultrafast magnetic recording in future memory devices.