Spin orbit torques in ferrimagnetic GdFeCo with various compositions

Abstract

Compositional dependence of spin–orbit torque (SOT) of the bilayer comprised of Ta and ferrimagnetic GdFeCo was investigated. Critical current density of SOT switching Jsw of the GdFeCo/Ta bilayers did not vary with Gd composition x, and were found to exhibit roughly Jsw = 11 MA cm−2. Two orthogonal components of SOT, damping-like torque τDL and field-like torque τFL were estimated by measuring harmonic Hall resistance under in-plane fields parallel and perpendicular to the AC current, respectively. The absolute values of SOT, ∣τ DL∣ and ∣τFL∣, were confirmed to be roughly constant within 22 ≤ x ≤ 28. On the other hand, the sign of τFL changed across the compensation composition. These results suggest that the injected spin current is considered to exert a torque to the transition metal FeCo moment rather than to the rare earth Gd moment.

Elucidation of the mechanism for maintaining ultrafast domain wall mobility over a wide temperature range

“…While the M s was minimum, the coercive fields reached their maximum at magnetic compensation composition. 19,20 The angular momentum compensation composition ( x AMC ) was determined using the following equations: M = M Gd + M FeCO where A i = M i / γ i , also M i (i = Gd or FeCo) is the magnetic moment and γ i = g i μ B / ħ is the corresponding g factor, and μ B and ħ are the Bohr magnetron and Planck constants, respectively. The g factor is g Gd ≈ 2.0 and g FeCo ≈ 2.16, 21,22 hence, the x AMC was estimated to be x AMC ∼ 23, as indicated in Fig.…”

“…Note that all measurements are performed at room temperature. 19,20 . The angular momentum compensation composition (x AMC ) was determined using the following equations:…”

“…While the M s was minimum, the coercive fields reached their maximum at magnetic compensation composition. 19,20 The angular momentum compensation composition (x AMC ) was determined using the following equations:…”

Elucidation of the Mechanism for Maintaining Ultrafast Domain Wall Mobility Over a Wide Temperature Range

“…We initially discern the magnetic properties of Gdx(Fe88Co12)100-x films. Figure 2 25,26 . The angular momentum compensation composition (xAMC) was determined using the following equations:…”

Learning phase transitions in the ferrimagnetic GdFeCo alloy

“…It has been shown that there is a possibility of ultra-fast switching magnetization by a femtosecond laser [9,21], which is promising for data storage. In addition, the widely varying stoichiometric composition provides opportunities to control the magnetic and spin transport properties of GdFeCo films [22,23]. In the presence of a perpendicular oriented external magnetic field, the GdFeCo alloy demonstrates the presence of a triple phase transition point with respect to the change of the external magnetic field (H) and the stoichiometric coefficient in the Gd x (FeCo) 1-x (x).…”