US-12622179-B2 - Magnetic field-free spin-orbit torque switching device using sapphire miscut substrate

US12622179B2US 12622179 B2US12622179 B2US 12622179B2US-12622179-B2

Abstract

Disclosed is a magnetic field-free spin-orbit torque switching device including a sapphire miscut substrate. More particularly, a spin-orbit torque switching device according to an embodiment includes a substrate having a step-terrace structure; and an input device formed on the substrate and provided with a heavy metal layer HM and a ferromagnetic layer FM.

Inventors

Chun Yeol YOU
Jin A Kim
Su Hyeok AN

Assignees

DAEGU GYEONGBUK INSTITUTE OF SCIENCE AND TECHNOLOGY

Dates

Publication Date: 20260505
Application Date: 20221019
Priority Date: 20211125

Claims (1)

1 . A spin-orbit torque switching device, comprising: a miscut substrate having a step-terrace structure; and an input device formed on the miscut substrate and provided with a heavy metal layer HM and a ferromagnetic layer FM, wherein the miscut substrate is a sapphire (Al 2 O 3 ) substrate, wherein the input device is patterned through etching after depositing a heavy metal layer and a ferromagnetic layer on the miscut substrate, and has the heavy metal layer HM disposed on the miscut substrate and the ferromagnetic layer FM disposed on the heavy metal layer HM, wherein the miscut substrate is miscut by 0.5° to 10° in an a-axis direction from the C-plane direction, and generates additional internal assistance when the current injected into the heavy metal layer is converted into spin current by the spin hall effect based on the miscut by 0.5° to 10°, and wherein the additional internal assistance implements a magnetic field-free spin-orbit torque switching by inducing in-plane symmetry breaking.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to Korean Patent Application No. 10-2021-0164468, filed on Nov. 25, 2021 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. BACKGROUND OF THE DISCLOSURE Field of the Disclosure The present disclosure relates to a spin-orbit torque switching device, and more particularly to a technical idea of implementing magnetic field-free switching using a sapphire miscut substrate. Description of the Related Art Recently, research on magnetic memory devices based on spin-orbit torque (SOT) has been actively conducted. A write process of a SOT-based magnetic memory device utilizes a heavy metal (HM)/ferromagnetic (FM) bilayer without an additional ferromagnetic layer required for a spin transfer torque memory device. Compared to an existing spin-transfer-torque (STT)-based magnetic memory device, the SOT-based magnetic memory device has higher switching efficiency compared to the same current, but requires the application of an in-plane magnetic field. Accordingly, since the need for an in-plane magnetic field at an input terminal for inputting information in device integration was considered to be a matter to be corrected, various studies on the absence of an in-plane magnetic field are being conducted as shown in FIG. 8-1 and FIG. 8-2. RELATED ART DOCUMENTS Patent Documents Korean Patent Application Publication No. 10-2021-0080575, “METHODS FOR FORMING STRUCTURES FOR MRAM APPLICATIONS” Korean Patent Application Publication No. 10-2011-0093007, “Method of forming surface pattern of sapphire, method of nitride semiconductor light emitting device, and nitride semiconductor light emitting device” SUMMARY OF THE DISCLOSURE Therefore, the present disclosure has been made in view of the above problems, and it is one object of the present disclosure to provide a spin-orbit torque switching device capable of implementing non-magnetic field switching by inducing symmetry breaking by changing the shape of a substrate, unlike a magnetic field-free spin-orbit torque-based information input device of an existing technology. It is another object of the present disclosure to provide a spin-orbit torque switching device that can be easily manufactured and is compatible with device measurement by inducing a symmetrical breaking effect by only replacing a substrate in an existing device with a miscut substrate. In accordance with an aspect of the present disclosure, the above and other objects can be accomplished by the provision of a spin-orbit torque switching device, including: a substrate having a step-terrace structure; and an input device formed on the substrate and provided with a heavy metal layer HM and a ferromagnetic layer FM. According to an aspect, the substrate may be miscut by 0.5° to 10° in an a-axis direction from the C-plane direction. According to an aspect, the substrate may be miscut by 0.5° to 10°, thereby implementing magnetic field-free spin-orbit torque switching by inducing in-plane symmetry breaking. According to an aspect, the substrate may be a sapphire (Al2O3) substrate having a step-terrace structure. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG. 1 illustrates a spin-orbit torque switching device according to an embodiment; FIG. 2 illustrates a cross-sectional conceptual view of a substrate according to an embodiment; FIG. 3 illustrates magnetic field strength-dependent magnetization reversal results of a spin-orbit torque switching device according to an embodiment; FIG. 4 illustrates a device characteristic using a sample deposited on a miscut sapphire substrate; FIG. 5 illustrates a magnetic field-free switching characteristic by SOT at φI=60°; FIG. 6 illustrates an effective anisotropy field characteristic calculated by a generalized sucksmith-thompson (GST) method as a function of φI; and FIG. 7 illustrates an embodiment of a spin-orbit torque switching device according to an embodiment. FIG. 8-1 shows various studies on the absence of an in-plane magnetic field are being conducted. FIG. 8-2 shows various studies on the absence of an in-plane magnetic field are being conducted. DETAILED DESCRIPTION OF THE DISCLOSURE The embodiments will be described in detail herein with reference to the drawings. However, it should be understood that the present disclosure is not limited to the embodiments according to the concept of the present disclosure, but includes changes, equivalents, or alternatives falling within the spirit and scope of the present disclosure. In the following description of the present disclosure, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present disclosure uncle