Concepedia

Rational Design of Two-Dimensional Metallic and Semiconducting Spintronic Materials Based on Ordered Double-Transition-Metal MXenes

Liang Dong, Hemant Kumar, Babak Anasori, Yury Gogotsi, Vivek B. Shenoy

The Journal of Physical Chemistry Letters · 2016 · 225 citations · 39 references

TL;DR

Two‑dimensional materials with robust ferromagnetism are sought for spintronic devices, yet suitable candidates remain elusive. We theoretically design ordered double‑transition‑metal MXenes to realize such ferromagnetic 2D materials. First‑principles calculations show that Ti₂MnC₂Tₓ, Hf₂MnC₂O₂, and Hf₂VC₂O₂ MXenes exhibit robust ferromagnetism with 3–4 μB per unit cell and Curie temperatures of 495–1133 K, outperforming known 2D ferromagnets, and that modest tensile strain can trigger semimetal‑to‑semiconductor and ferromagnetic‑to‑antiferromagnetic transitions.

Abstract

Two-dimensional (2D) materials that display robust ferromagnetism have been pursued intensively for nanoscale spintronic applications, but suitable candidates have not been identified. Here we present theoretical predictions on the design of ordered double-transition-metal MXene structures to achieve such a goal. On the basis of the analysis of electron filling in transition-metal cations and first-principles simulations, we demonstrate robust ferromagnetism in Ti2MnC2Tx monolayers regardless of the surface terminations (T = O, OH, and F), as well as in Hf2MnC2O2 and Hf2VC2O2 monolayers. The high magnetic moments (3-4 μB/unit cell) and high Curie temperatures (495-1133 K) of these MXenes are superior to those of existing 2D ferromagnetic materials. Furthermore, semimetal-to-semiconductor and ferromagnetic-to-antiferromagnetic phase transitions are predicted to occur in these materials in the presence of small or moderate tensile in-plane strains (0-3%), which can be externally applied mechanically or internally induced by the choice of transition metals.