Spin Hall Electrode Alloy for Lower-Energy SOT-MRAM Switching
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Solution Overview
Problem
The switching energy of Spin Orbit Torque Magnetic Random Access Memory (SOT-MRAM) is limited, hindering further performance improvements due to high in-plane charge current requirements for programming operations.
Innovation Solution
A Spin Hall electrode (SHE) formed from a metal alloy comprising a heavy metal element with 5d electrons and a light transition metal element with partially filled 3d orbitals, such as platinum-chromium or platinum-vanadium alloys, is used to enhance spin Hall conductivity and reduce electrical resistivity, thereby lowering the in-plane charge current and switching energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional spin Hall electrode materials are used in SOT-MRAM, then the device structure is simple, but the in-plane charge current requirement is high and switching energy is limited
Solution Approach 1:
The patent applies composite materials by combining heavy metal elements (Pt, Pd, Ir) with light transition metal elements (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) to form alloy spin Hall electrodes. This composite approach leverages the high spin Hall angle of heavy metals and the low electrical resistivity of light transition metals, achieving reduced switching energy through synergistic material properties rather than using single-element materials.
Solution Approach 2:
The patent implements parameter changes by systematically varying the composition ratios of heavy metal to light transition metal elements in the alloy. By adjusting these compositional parameters, the patent optimizes the balance between spin Hall angle and electrical resistivity, thereby tuning the switching energy and in-plane charge current requirements to achieve optimal performance.
2Reliability
If high in-plane charge current is applied for programming, then reliable data writing is achieved, but switching energy increases and performance improvement is hindered
Solution Approach 1:
The patent changes the material parameters of the spin Hall electrode by using alloys with optimized composition ratios of heavy metal to light transition metal elements. This parameter optimization enhances spin Hall conductivity while minimizing electrical resistivity, allowing reliable data writing at lower in-plane charge currents and reduced switching energy.
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 use of these alloys in the SHE significantly reduces the in-plane charge current and switching energy requirements, improving energy efficiency and data retention in SOT-MRAM by enhancing spin Hall conductivity and minimizing shunting ratios.
Implementation Method 1
a spin Hall electrode (SHE), in contact with the MTJ and configured to convert a charge current to a spin current for programming the MTJ
Data Source
AI summary
A memory device and a manufacturing method thereof are provided. The memory device includes a magnetic tunneling junction (MTJ) and a spin Hall electrode (SHE). The MTJ includes a free layer, a reference layer and a barrier layer lying between the free layer and the reference layer. The SHE is in contact with the MTJ, and configured to convert a charge current to a spin current for programming the MTJ. The SHE is formed of an alloy comprising at least one heavy metal element and at least one light transition metal element. The heavy metal element is selected from metal elements with one or more valence electrons filling in 5d orbitals, and the light transition metal element is selected from transition metal elements with one or more valence electrons partially filling in 3d orbitals.