[21p-C501-1~19] 10.3 Spin devices, magnetic memories and storages

6:30 PM - 6:45 PM JST(9:30 AM - 9:45 AM UTC)English Presentation

[21p-C501-19] Ultra-High Domain Wall Velocity in GdFe Thin Films for Racetrack Memory Applications

〇(P)Mojtaba Mohammadi¹, Satoshi Sumi¹, Pham Van Thach², Kenji Tanabe¹, Hiroyuki Awano¹ (1.Toyota Technological Institute, 2.Vietnam Academy of Science and Technology)

Keywords:

Racetrack Memory,current-Induced Domain Wall Motion,GdFe ferrimagnetic nanowire

Racetrack memory (RM) works by using magnetic nanowires to store data as magnetic domains, which can be moved along the nanowires to access different pieces of information Domain walls (DWs) in thin magnetic films can be moved along the track using spin-polarized currents [1]. Extensive research efforts have been directed towards enhancing the velocity of domain wall motion, including advancements in material properties and the optimization of wire geometries [2,3]. In this study, a series of Pt(5nm)/Gd_xFe_1-x(20nm)/SiN(10nm) thin films were deposited by magnetron sputtering. The magnetic wire with 3 µm wide and 60 µm long were micro-fabricated by an electron-beam lithography system and a lift-off method. Fig. 1(a) and (b) show the dependence of DW velocity as a function of current density for Pt/Gd_24.5Fe_75.5/SiN wires, measured with a pulse duration of 30, 10, 3 and 1 ns for samples with 3 and 5 µm wire width, respectively. The maximum DW velocity, i.e., V_DW = 2800 m/s, was observed for 1 ns pulse duration without the application of an in-plane external magnetic field, which is the fastest DW velocity yet in comparison with the previous reports. Besides, the DW velocity as a function of pulse duration for 3 µm wire width in the current density of J =3×10¹¹ A/m² is illustrated in figure 1(c). The inset is the real images of DW displacement for the samples. Similarly, fixing the current density and increasing the pulse width should increase the DW displacement. However, contrary to what was anticipated, the velocity of the DW decreased. This unexpected outcome could be attributed to the impact of Joule heating. These findings present an opportunity for technological advancements in the development of a novel form of RM that offers both low power consumption and stable high velocity.