National University of Singapore

Samsung Electronics Co., Ltd.

Yonsei University

Hyunsoo Yang

Xuepeng Qiu

Jae Hyun Kwon

Jongmin Lee

Young Jun Shin

Rajagopalan Ramaswamy

Rahul Mishra

Kaiming Cai

Shuyuan Shi

Ung Hwan Pi

Antonio Helio Castro Neto

Wonho Lee

Jong-Hyun Ahn

Yi Wang

Charanjit Singh Bhatia

Yang Liu

Yang Wu

William Sylvain Legrand

Sankha Subhra Mukherjee

Kulothungasagaran Narayanapillai

Gopinadhan Kalon

Li Ming Loong

Wee Tee Soh

Jiawei Yu

Jungbum Yoon

Described is a spin torque device, and a spintronics device Incorporating the spin torque device. The spin torque device comprises a magnetic layer having a switchable magnetisation direction along a first axis, and a spin source layer adapted to generate a spin current from a current Injected along a second axis perpendicular to the first axis. Electrons of different spins in the spin source layer are rearranged by scattering so the spin current is generated in a plane perpendicular to the second axis and polarized at an angle to the first axis, so that the spin current diffuses into the magnetic layer to produce spin torque to switch the magnetisation direction.

Spin torque device having a spin current polarized at a canting angle of out-of-plane spin

A semiconductor memory device may be provided. The semiconductor memory device may include data storage patterns having respective first sides and respective second sides, a spin-orbit coupling (SOC) channel layer in common contact with the first sides of the data storage patterns, the SOC channel layer is configured to provide a spin-orbit torque to the data storage patterns, read access transistors connected between the second sides of respective ones of the data storage patterns and respective data lines, a write access transistor connected between a first end of the SOC channel layer and a source line, and a bit line connected to a second end of the SOC channel layer. Each of the data storage patterns comprises a free layer in contact with the SOC channel layer and an oxygen reservoir layer in contact with the free layer.

Semiconductor memory device with spin-orbit coupling channel

A spin-orbit torque deviceis described. In an embodiment, the spin-orbit torque devicecomprises: a first pinning regionhaving a first fixed magnetization direction; a second pinning regionhaving a second fixed magnetization direction which is in a different direction to the first fixed magnetization direction; a magnetic layerhaving a switchable magnetization direction; and a spin source layerconfigured to generate a spin current for propagating a domain wall between the first and second pinning regionsto switch the switchable magnetization direction of the magnetic layerbetween the first and second fixed magnetization directions.

Spin-orbit torque device and method for operating a spin-orbit torque device

In example embodiments, an RF-to-DC converter includes one or more unit cells that integrate a spintronic element (e.g., a magnetic tunnel junction (MTJ)) into a conductor ring RF energy absorber (e.g., a split-ring resonator (SRR)). A RF-to-DC converter that includes one or more MTJ-integrated SRR unit cells may provide compactness, as each unit cell includes its own independent SRR and integrated MTJ; scalability, as multiple unit cells may be connected into an array to increase DC power output; and energy harvesting efficiency, as a MTJ may be much more sensitive than a Schottky diode and the SRR of each unit cell may directly feed energy to a MTJ without impedance matching circuits.

Split-ring resonator with integrated magnetic tunnel junction for highly sensitive and efficient energy harvesting

In one embodiment, a SOT device is provided that replaces a traditional NM layer adjacent to a magnetic layer with a NM layer that is compatible with CMOS technology. The NM layer may include a CMOS-compatible composite (e.g., CuPt) alloy, a TI (e.g., BiSe, BiSe, BiSb, etc.) or a TI/non-magnetic metal (e.g., BiSe/Ag, BiSe/Ag, BiSb/Ag, etc.) interface, that provides efficient spin current generation. Spin current may be generated in various manners, including extrinsic SHE, TSS or Rashba effect.

Spin orbit materials for efficient spin current generation

In example embodiments, a SOT magnetic memory and operation method are provided that utilize SOT driven domain wall motion to achieve subsequent switching without the need for an external assist magnetic field. The magnetic memory includes a magnetic tunnel junction having a reference layer, a tunnel barrier layer and a free layer, where the tunnel barrier layer is positioned between the reference layer and free layer. A spin-orbit torque layer is disposed adjacent to the free layer. A pair of pinning site are positioned at a longitudinal end of the free layer and each has an opposite magnetization direction from the other. The SOT layer is configured to exert SOT and switch a magnetization direction of the free layer via domain wall motion in a direction of current flow when an electric current is passed through a length of the SOT layer.

Magnetic memory and a method of operating magnetic memory

In various embodiments, techniques are provided for unipolar SOT switching of a magnetic memory, using current pulses with differing pulse durations or current densities. For example, to switch a MTJ to a high resistance state, in-plane current pulses having a first pulse duration may be applied. To switch the MTJ to a low resistance state, in-plane current pulses having a second pulse duration may be applied. The pulse's polarity and current density may be fixed, and the polarity and magnitude of an in-plane assist field may be fixed. Alternatively, to switch a MTJ to a high resistance state in-plane current pulses having a first current density may be applied. To switch the MTJ to a low resistance state in-plane current pulses having a second current density may be applied. The pulse's polarity and duration may be fixed, and the polarity and magnitude of an in-plane assist field may be fixed.

Unipolar switching of magnetic memory

A graphene structure is provided. The graphene structure comprises a substrate layer and at least two graphene layers disposed on the substrate. The at least two graphene layers comprises a gate voltage tuned layer and an effective graphene layer and the effective graphene layer comprises one or more graphene layers. A magnetoresistance ratio of the graphene structure is determined by a difference in a charge mobility and/or a carrier density between the gate voltage tuned layer and the effective graphene layer. The charge mobility and/or the carrier density of the gate no voltage tuned layer is tunable by a gate voltage applied to the graphene structure. A magnetic field sensor comprising the graphene structure is also provided.

Graphene based magnetoresistance sensors

In one embodiment, a spin torque device uses a thick (e.g., &#x3e;1 nm, and preferably &#x3e;=2-6 nm) ferrimagnet (FIM) layer, instead of a thin (e.g., &#x3c;1-2 nm) FM layer in the device's stack. The FIM layer may be composed of a cobalt-gadolinium (Co&#x2014;Gd) alloy, cobalt-terbium (Co&#x2014;Tb) multilayers, or other materials that provide anti-ferromagnetic coupling between two sub-lattices. Negative exchange interaction between the two sub-lattices of the FIM may allow for low current switching. High thermal stability and external magnetic field resistance may also be achieved.

High efficiency spin torque switching using a ferrimagnet

In one embodiment, a desirable (e.g., substantially 100%) SOT switching probability is achieved in a SOT device by applying in-plane input current as one or more pulses having a tuned pulse width. In the case of a single pulse, pulse width may be selected as a single tuned pulse width or a range of pulse widths that avoid a specific pulse width determined to cause a switch-back response. In the case of multiple pulses, pulse width, a time interval between pulses and other factors such as intensities may be selected to prevent a switch-back response. Further, SOT switching speed may be achieved by reducing incubation delay through modification of an external magnetic field or input current density applied to the SOT device.

Techniques to improve switching probability and switching speed in SOT devices

In one embodiment, a SO-STT device has a non-symmetric device geometry. The device may be fabricated to have a non-symmetric magnetic pattern by tilting a shaped magnetic pattern (e.g., an ellipse, diamond, rectangle, etc. shaped magnetic pattern) such that the pattern's main (long and short) axes are tilted with respected to an in-plane current direction. Alternatively, the non-symmetric device geometry may be produced by locating the magnetic pattern away from the center of a current injection line. The non-symmetric may permit switching absent application of an external magnetic field. A SO-STT device with non-symmetric device geometry, or another type of SO-STT device, may further integrate an additional semiconductor, insulator or metal layer into the device's multilayer stack. By integrating the additional semiconductor, insulator or metal layer, a significant reduction of SO-STT switching current density may be achieved. Depending on the embodiment, the additional semiconductor, insulator or metal layer may be disposed adjacent to the FM layer, or within the FM layer, among other possibilities.

Techniques to modulate spin orbit spin transfer torques for magnetization manipulation

Various embodiments relate a method for depositing a layer onto a workpiece using plasma. The method comprises arranging the workpiece and a source material inside a vacuum chamber. The method also comprises applying energy to the source material to cause atoms of the source material to be ejected from a surface of the source material into a plasma. The method further comprises orientating the workpiece with respect to the source material to prevent direct propagation of the ejected atoms from the source material to a work surface of the workpiece and to permit deposition of the layer onto the workpiece by ejected atoms which impact the work surface after colliding with particles of the plasma. Various embodiments also provide a corresponding apparatus.

Method and an apparatus for depositing a layer onto a workpiece using plasma

Systems and methods for spinwave-based metrology in accordance with embodiments of the disclosure involve generating and detecting spinwaves in a sample having a ferromagnetic material; and determining a material thickness, a material integrity measure, a presence of a manufacturing defect, a categorical type of manufacturing defect, and/or a manufacturing process statistic corresponding to spinwave behavior in the sample. In an embodiment, spinwaves are generated by way of concurrent exposure of a target measurement site of the sample to each of a bias magnetic field and radiation (e.g., microwave or radio frequency radiation) produced by a first set of integrated waveguides. A response signal corresponding to a behavior of spinwaves within the target measurement site can be generated by way of a second set of integrated waveguides. Various embodiments of systems and methods for generating spinwaves, detecting spinwaves, and calculating, analyzing, or monitoring one or more sample properties can be automated.

Spinwave based nondestructive material, structure, component, or device testing tools

A spin orbit torque-based spintronics device that includes a ferromagnet layer having a first surface and a second surface opposed to each other, a metal layer and a spacer layer covering the first surface and the second surface of the ferromagnet layer, respectively, and an dielectric layer covering either the metal layer or the spacer layer. Also disclosed are two related spin orbit torque-based spintronics devices and methods of using these three spintronics devices.

Spin orbit and spin transfer torque-based spintronics devices

Disclosed is a graphene-based terahertz device that includes a top graphene layer, a bottom graphene layer, and a middle layer disposed between the top graphene layer and the bottom graphene layer. The middle layer is a liquid crystal layer, a piezocrystal layer, an ionic liquid layer, or an ion gel layer. Also disclosed are methods of preparing different embodiments of the above-described graphene-based terahertz device.

Growing community of inventors

Singapore, Singapore

Hyunsoo Yang