# Multi-bit MRAM storage cells utilizing serially connected perpendicular magnetic tunnel junctions

## TL;DR

This paper proposes a multi-bit MRAM cell design using serially connected perpendicular magnetic tunnel junctions, achieving higher storage density with promising stability and manufacturability.

## Contribution

It introduces a novel multi-bit MRAM cell architecture with serial pMTJs on a single wafer, demonstrating increased capacity and stability.

## Key findings

- Tunneling magnetoresistance above 130%
- Current-induced magnetization switching without external magnetic field
- Thermal stability of multi-bit cells

## Abstract

Serial connection of multiple memory cells using perpendicular magnetic tunnel junctions (pMTJ) is proposed as a way to increase magnetic random access memory (MRAM) storage density. Multi-bit storage element is designed using pMTJs fabricated on a single wafer stack, with a serial connections realized using top-to-bottom vias. Tunneling magnetoreistance effect above 130%, current induced magnetization switching in zero external magnetic field and stability diagram analysis of single, two-bit and three-bit cells are presented together with thermal stability. The proposed design is easy to manufacture and can lead to increase capacity of future MRAM devices.