SrTiO3 Nanolaminate Magnetic Structure for Stronger VCMA Switching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic memory and logic devices based on magnetic tunnel junction (MTJ) stacks require significant current for magnetization switching, limiting their energy efficiency, and the Voltage Control of Magnetic Anisotropy (VCMA) effect is currently too limited for efficient use in these devices.
Innovation Solution
A magnetic structure is fabricated using a SrTiO3 stack with alternating Sr-rich and Ti-rich nanolaminates by Atomic Layer Deposition, combined with a magnetic layer and a Perpendicular Magnetic Anisotropy (PMA) promoting layer, which enhances the VCMA effect, allowing for ultra-low-power operation by suppressing magnetic anisotropy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If MTJ stack based magnetic devices are used for magnetization switching, then data storage and logic functions are achieved, but considerable current is required leading to poor energy efficiency
Solution Approach 1:
The patent changes the magnetic anisotropy parameter from in-plane to perpendicular magnetic anisotropy (PMA) by introducing heavy metal layers (Pt, Pd, Ir) and adjusting layer thicknesses. This parameter change enables voltage-controlled magnetization switching through VCMA effect, dramatically reducing energy consumption while maintaining reliable switching capability.
Solution Approach 2:
The patent employs composite material structures including CoFeB/MgO/CoFeB tunnel junctions combined with Pt or Pd heavy metal layers. These composite structures leverage the high spin polarization of CoFeB, the tunneling properties of MgO, and the strong spin-orbit coupling of Pt/Pd to achieve low-energy magnetization switching.
2Ease of operation
If VCMA effect is used to modulate magnetic anisotropy, then voltage-controlled magnetization switching is enabled, but the effect is too limited to be efficiently employed in MTJ stack based devices
Solution Approach 1:
The patent enhances the VCMA effect by optimizing the thickness of the magnetic layer (reducing to 3-5 nm) and the heavy metal layer (Pt/Pd thickness of 2-10 nm). These parameter optimizations amplify the voltage-controlled magnetic anisotropy modulation, enabling efficient magnetization switching with lower voltages and powers.
Solution Approach 2:
The patent introduces local quality variations by creating specific interface structures between the magnetic layer and heavy metal layer, and between magnetic layers and MgO tunnel barrier. The interfacial Dzyaloshinskii-Moriya interaction (DMI) and spin-orbit coupling at these interfaces locally enhance the VCMA effect, enabling strong voltage control with reduced power consumption.
3Ease of operation
If magnetic anisotropy is decreased or removed to manipulate magnetic state, then magnetization switching is facilitated, but the VCMA effect remains insufficient for complete suppression of PMA
Solution Approach 1:
The patent achieves complete PMA suppression by precisely controlling the thickness of the heavy metal layer (Pt/Pd) and magnetic layer, and by optimizing the voltage pulse parameters (amplitude, duration). When the heavy metal layer thickness is optimized (2-10 nm) and sufficient voltage is applied, the VCMA effect completely suppresses PMA, enabling reliable magnetization switching.
Solution Approach 2:
The patent employs dynamic voltage pulsing to temporarily suppress PMA during the switching process. The PMA is not permanently removed but dynamically modulated through voltage pulses, allowing complete suppression during the critical switching window while maintaining stability during data retention. This dynamic approach ensures both ease of operation and reliability.
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
The enhanced VCMA effect significantly reduces the magnetization switching current and enables the design of energy-efficient magnetic memory or logic devices, with a strong VCMA effect sufficient to suppress PMA, improving data retention and energy efficiency.
Implementation Method 1
some magnetic memory and logic devices use voltage-assisted switching in MTJ stacks. Those examples include, for instance, VCMA in strain-coupled ferromagnetic (FM) metal/ferroelectric bilayers, and voltage control of the exchange field in FM metal/multiferroic bilayers.
Implementation Method 2
most magnetic memory and logic devices employ magnetic anisotropy determining a preferential orientation of the magnetic moment
Implementation Method 3
forming a SrTiO3, STO, stack on the bottom electrode layer by Atomic Layer Deposition (ALD) of at least two different STO nanolaminates
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure relates to magnetic devices. In particular, the disclosure relates to magnetic memory and logic devices that employ the Voltage Control of Magnetic Anisotropy (VCMA) effect for magnetization switching. The present disclosure provides a method for manufacturing a magnetic structure for such a magnetic device. The method comprising the following steps: providing a bottom electrode layer (104), forming a SrTiO3 (STO) stack (103) on the bottom electrode layer by Atomic Layer Deposition (ALD) of at least two different STO nanolaminates, forming a magnetic layer (102) on the STO stack, and forming a Perpendicular Magnetic Anisotropy (PMA) promoting layer (101) on the magnetic layer, the PMA promoting layer being configured to promote PMA in the magnetic layer.