MESO Logic Device Magnetoelectric Switching Energy Reduction
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Solution Overview
Problem
Existing spintronic logic devices, such as Magnetic Tunnel Junctions (MTJs), face challenges with high energy consumption, long switching times, and high write error rates due to the need for large write currents and voltages, as well as reliability issues related to tunneling current in the spin filtering tunneling dielectric.
Innovation Solution
The implementation of Magnetoelectric Spin Orbit Logic (MESO) devices, which utilize a symmetric tunneling barrier or spin-filter stack to enhance spin injection efficiency and reduce switching energy by leveraging the magnetoelectric effect for faster and more efficient magnetization switching, achieving lower power consumption and improved reliability through charge-to-spin and spin-to-charge conversion mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large write current is used to switch magnetization in MTJs, then switching reliability is improved, but energy consumption increases and switching time increases
Solution Approach 1:
The patent changes the switching mechanism from spin-transfer torque (STT) requiring large currents to magnetoelectric coupling that uses electric field to control magnetization. By applying voltage to the ferroelectric layer, the magnetic anisotropy is modified, enabling low-energy magnetization switching without large write currents, thus resolving the contradiction between reliability and energy consumption
Solution Approach 2:
The patent replaces the mechanical/electrical spin-current mechanism with a field-based magnetoelectric coupling mechanism. Instead of using spin-polarized current to exert torque on the magnetization, the system uses electric field from the ferroelectric layer to directly modify the magnetic anisotropy energy landscape, enabling deterministic switching at much lower energy
2Reliability
If large write current is applied to switch magnetization, then switching reliability is improved, but switching speed decreases
Solution Approach 1:
The patent modifies the switching mechanism by changing from current-driven spin torque to voltage-driven magnetoelectric coupling. The electric field from the ferroelectric layer rapidly modifies the magnetic anisotropy, enabling fast magnetization switching on the order of nanoseconds or faster, thus improving both speed and reliability simultaneously
3Reliability
If spin filtering tunneling dielectric is used in MTJs, then spin polarization is achieved, but tunneling current causes reliability issues
Solution Approach 1:
The patent extracts and removes the problematic spin filtering tunneling dielectric layer from the MTJ structure. Instead of relying on tunneling through the MgO barrier which generates harmful tunneling currents and reliability issues, the system uses direct magnetoelectric coupling between the ferroelectric and ferromagnetic layers, eliminating the source of tunneling current while maintaining spin control functionality
Solution Approach 2:
The patent introduces a direct interface between the ferroelectric layer and the ferromagnetic layer as an intermediary mechanism. This direct coupling allows the electric field to act on the magnetic moments without requiring a tunneling barrier, thereby eliminating tunneling current while maintaining the ability to control magnetization state
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
MESO logic devices demonstrate faster switching times (100 ps) and lower switching energy (1-10 aJ) compared to traditional spintronic devices, with improved spin injection efficiency from 10% to 90% and a boosted spin-orbit output signal, enabling reduced power consumption and enhanced computational efficiency.
Implementation Method 1
a magnetoelectric layer operable to switch the magnetization of the magnet in response to an applied electrical field
Implementation Method 2
a stack of layers comprising spin-orbit material, a portion of the stack adjacent to the third magnet, the stack configured to convert the spin current to a charge current
Implementation Method 3
symmetric tunneling barrier or spin-filter stack to enhance spin injection efficiency
Data Source
AI summary
An apparatus is provided to improve spin injection efficiency from a magnet to a spin orbit coupling material. The apparatus comprises: a first magnet; a second magnet adjacent to the first magnet; a first structure comprising a tunneling barrier; a third magnet adjacent to the first structure; a stack of layers, a portion of which is adjacent to the third magnet, wherein the stack of layers comprises spin-orbit material; and a second structure comprising magnetoelectric material, wherein the second structure is adjacent to the first magnet.