# Thermally nucleated magnetic reversal in CoFeB/MgO nanodots

## TL;DR

This paper investigates the magnetic reversal mechanisms in CoFeB/MgO nanodots, revealing thermally nucleated incoherent switching and intrinsic thermal field distributions that limit device reliability at small scales.

## Contribution

It demonstrates that magnetic reversal in these nanodots is thermally nucleated and incoherent, establishing an intrinsic thermal switching field distribution affecting device performance.

## Key findings

- Reversal mechanism is incoherent and thermally nucleated.
- Intrinsic thermal switching field distribution exists.
- Limits to reversal reliability in small magnetic nanodevices.

## Abstract

Power consumption is the main limitation in the development of new high performance random access memory for portable electronic devices. Magnetic RAM (MRAM) with CoFeB/MgO based magnetic tunnel junctions (MTJs) is a promising candidate for reducing the power consumption given its non-volatile nature while achieveing high performance. The dynamic properties and switching mechanisms of MTJs are critical to understanding device operation and to enable scaling of devices below 30 nm in diameter. Here we show that the magnetic reversal mechanism is incoherent and that the switching is thermally nucleated at device operating temperatures. Moreover, we find an intrinsic thermal switching field distribution arising on the sub-nanosecond timescale even in the absence of size and anisotropy distributions or material defects. These features represent the characteristic signature of the dynamic properties in MTJs and give an intrinsic limit to reversal reliability in small magnetic nanodevices.