Reversal-mechanism of perpendicular switching induced by an in-plane current

Abstract

We propose a magnetization reversal model to explain the perpendicular switching of a single ferromagnetic layer induced by an in-plane current. Contrary to previously proposed reversal mechanisms that such magnetic switching is directly from the Rashba or spin Hall effects, we suggest that this type of switching arises from the current-induced chirality dependent domain wall motion. By measuring the field dependent switching behaviors, we show that such switching can also be achieved between any two multidomain states, and all of these switching behaviors can be well explained by this model. This model indicates that the spin Hall angle in such structures may be overestimated and also predicts similar switching behaviors in other ferromagnetic structures with chiral domain walls or skyrmions.2

Anomalous spin-orbit torque switching in synthetic antiferromagnets

“…Above the critical value, a domain can still be thought as a uniform magnetization with higher magnetic energy that is unstable under the large current. As demonstrated before, the separate control of V D for two types of DWs can be realized in HM/FM bilayers and V RD depends on the strength of applied in-plane fields [19,20]; therefore, a large enough field is necessary to realize a full SOT switching [2][3][4]27] in these structures.…”

“…It is shown that the SOT switching direction of SAFs can be reversed depending on the strength of applied in-plane fields, even with the same sign of SHA. These results indicate that the switching of SAFs can be achieved without any direction changes of the applied in-plane field and current, contrary to the switching of a single ferromagnet [2][3][4]12,14,18,[23][24][25]27] in which the direction of either current or in-plane field has to be reversed. The observed anomalous magnetization switching (AMS) behaviors invalidate the conventional macrospin model and prompt a new understanding of SOT switching.…”

“…Therefore σ and the switching directions in Pt/ferromagnet (Pt/FM) and Ta/FM structures are opposite [2][3][4]8,10,[12][13][14][15][16][17]. So far all reported SOT switchings are the SOT switchings of a single ferromagnet [2][3][4]12,14,18,[23][24][25]27], in which reversing either current or in-plane field is necessary to switch magnetization [2][3][4]12,14,18,[23][24][25]27] and the switching rule shown in Figs. 1(a) and 1(b) is well obeyed.…”

Electrical Control of Metallic Heavy-Metal–Ferromagnet Interfacial States

“…However, many aspects of SOT switching are still under debate. For example, the origin of SOTs can be spin Hall effects (SHEs) [40][41][42] or Rashba effects [11,43], and their roles during the switching process are still not clear [11,41,42,[44][45][46]. Generally, the SOT switching starts from a reversal domain nucleation in a uniform magnetization state and then the nucleated domains expand to the entire film [44,47,48].…”

Enhanced Spin-Orbit Torque via Modulation of Spin Current Absorption

“…Conventional spin transfer torque (STT) utilizes the spin polarized current to transfer angular momentum from one FM to another FM [5,6], and it has been applied to various spintronic devices such as a magnetic random access memory (MRAM) [7][8][9] and race-track domain wall memory [10]. Recently emerging spin-orbit torque (SOT) opens a new prospect in the magnetization manipulation of the HM=FM bilayers [1,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. In a SOT device, the electrons flowing in a HM layer with strong spin-orbit coupling are spin polarized and the subsequent spin current transfers its angular momentum to the adjacent FM.…”