Ultrafast All-Optical Switching of Magnetic Tunnel Junctions With Sub-Picosecond Infrared Laser Pulses

Time: Wednesday, October 24th, 15:40
Speaker: Mo LI, Minnesota

All-optical switching (AOS) has been extensively explored for its prospects of enabling ultrafast magnetic recording and operation of spintronic devices. Nevertheless, there has not been any demonstration of AOS in realistic spintronic devices, such as magnetic tunnel junctions (MTJs). Since previous studies of AOS have only been performed on a single magnetic layer, how additional magnetic layers affect the AOS phenomenon remains unknown. In this work, we develop a perpendicularly magnetized MTJ (p-MTJ) employing GdFeCo as the free layer. We demonstrate, for the first time, all-optical switching of an MTJ, without using any external magnetic field, but rather with single sub-picosecond infrared laser pulses. The switching is read out electrically through measuring the tunneling magnetoresistance (TMR). We further demonstrate MHz repetition rate of switching GdFeCo film, which is limited by our instruments, but the fundamental upper limit of this rate should be higher than tens of GHz as has been revealed by previous time-resolved studies28. The demonstrated picosecond switching time of an MTJ by AOS is two orders of magnitude faster than that of any other switching methods.