Giant Perpendicular Magnetic Anisotropy Enhancement in MgO-Based Magnetic Tunnel Junction by Using Co/Fe Composite Layer

journal article in Web of Science

English

Magnetic tunnel junctions with perpendicular anisotropy form the basis of the spin-transfer torque magnetic random-access memory (STT MRAM), which is nonvolatile, fast, dense, and has quasi-infinite write endurance and low power consumption. Based on density-functional-theory (DFT) calculations, we propose an alternative design of magnetic tunnel junctions comprising Fe(n)Co(m)Fe(n)|MgO storage layers [n and m denote the number of monolayers (ML)] with greatly enhanced perpendicular magnetic anisotropy (PMA) up to several mJ/m(2), leveraging the interfacial perpendicular anisotropy of Fe vertical bar MgO along with a strain-induced bulk PMA discovered within bcc Co. This giant enhancement dominates the demagnetizing energy when increasing the film thickness. The tunneling magnetoresistance (TMR) estimated from the Julliere model is comparable with that of the pure Fe vertical bar MgO case. We discuss the advantages and pitfalls of a real-life fabrication of the structure and propose the Fe(3ML)Co(4ML)Fe(3ML) as a storage layer for MgO-based STT MRAM cells. The large PMA in strained bcc Co is explained in the framework of second-order perturbation theory by the MgO-imposed strain and consequent changes in the energies of d(yz) and d(z2) minority-spin bands.

Magnetic Anisotropy; MgO-Based Magnetic Tunnel

VOJÁČEK, L.; IBRAHIM, F.; HALLAL, A.; DIENY, B.; CHSHIEV, M.

8. 2. 2021

AMER PHYSICAL SOC

COLLEGE PK

2331-7019

Physical Review Applied

15

2

United States of America

024017-1

024017-8

8

https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.15.024017