First-principles prediction of high Curie temperature for ferromagnetic bcc-Co and bcc-FeCo alloys and its relevance to tunneling magnetoresistance

TL;DR

This paper uses first-principles calculations to predict high Curie temperatures in bcc-Co and FeCo alloys, indicating potential for high-performance magnetic tunnel junctions at room temperature.

Contribution

It provides the first-principles prediction of the Curie temperature for bcc-Co and FeCo alloys, highlighting their suitability for spintronic applications.

Findings

bcc-Co has a predicted Tc of 1420 K.

bcc-Co/MgO/bcc-Co junctions could achieve high magnetoresistance at room temperature.

Curie temperatures were calculated using a Heisenberg model and Monte Carlo simulations.

Abstract

We determine from first-principles the Curie temperature Tc for bulk Co in the hcp, fcc, bcc, and tetragonalized bct phases, for FeCo alloys, and for bcc and bct Fe. For bcc-Co, Tc=1420 K is predicted. This would be the highest Curie temperature among the Co phases, suggesting that bcc-Co/MgO/bcc-Co tunnel junctions offer high magnetoresistance ratios even at room temperature. The Curie temperatures are calculated by mapping ab initio results to a Heisenberg model, which is solved by a Monte Carlo method.