Stabilizing and increasing the magnetic moment of half-metals: The role of Li in half-HeuslerLiMnZ(Z=N,P,Si)

Abstract

Li-based half-Heusler alloys have attracted much attention due to their potential applications in optoelectronics and because they carry the possibility of exhibiting large magnetic moments for spintronic applications. Due to their similarities to metastable zinc blende half-metals, the halfHeusler alloys β-LiMnZ (Z = N, P and Si) were systematically examined for their electric, magnetic and stability properties at optimized lattice constants and strained lattice constants that exhibit half-metallic properties. Other phases of the half-Heusler structure (α and γ) are also reported here, but they are unlikely to be grown. The magnetic moments of these stable Li-based alloys are expected to reach as high as 4 μ B per unit cell when Z = Si and 5 μ B per unit cell when Z = N and P, however the antiferromagnetic spin configuration is energetically favored when Z is a pnictogen. β-LiMnSi at a lattice constant 14% larger than its equilibrium lattice constant is a promising half-metal for spintronic applications due to its large magnetic moment and vibrational stability. The modified Slater-Pauling rule for these alloys is determined. Finally, a plausible method for developing halfmetallic LixMnZ at equilibrium, by tuning x, is investigated, but, unlike tetragonalization, this type of alloying introduces local structural changes that destroy the half-metallicity.

A half-metallic half-Heusler alloy having the largest atomic-like magnetic moment at optimized lattice constant

“…If Z is a group IV element, then the moment is 4 µ B per Mn. 8 However, the lattice constants are consistently larger than the optimized values. This may be caused by the fact that the pnictides and Si do not have a sufficiently strong enough electronegativity.…”

“…For example, Damewood et al examined half-metallic properties and stability of lithiated half-Heusler alloys, LiMnZ (Z=N, P, Si). 8 They found that the studied alloy exhibit half-metallic properties at lattice constants larger than its' optimized lattice constant. In fact, many zinc-blende (ZB) compounds, such as MnZ, are not half-metallic at their equilibrium lattice constants but can also a To whom correspondence should be addressed.…”

“…1 shows the C1 b structure. Many of half-Heusler alloys have been predicted to be half-metals 7,8 with lattice constants deviating away (mostly larger) from the optimized lattice constants. For example, Damewood et al examined half-metallic properties and stability of lithiated half-Heusler alloys, LiMnZ (Z=N, P, Si).…”

Largest Magnetic Moments in the Half-Heusler Alloys XCrZ (X = Li, K, Rb, Cs; Z = S, Se, Te): A First-Principles Study

“…Then, quite a lot of half-Heusler alloys [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] had been predicted to be HM materials (HMMs). Recently, the electronic, magnetic, and stability properties were systematically investigated by first principles calculation in half-Heusler alloys of LiMnZ (Z = N, P, Si) [ 16 ]. Damewood et al found that these LiMnZ (Z = N, P, Si) alloys show HM behaviors with large semiconducting-type band-gaps and magnetic moments (>3 μ B per formula unit) at their strained lattice constants.…”

Theoretical Study of the Electronic and Magnetic Properties and Phase Stability of the Full Heusler Compound Pd2CoAl

“…The Heusler alloys generally have two variants of stoichiometric compositions: the half-Heusler compound with generic formula of XYZ [52][53][54][55][56][57] and the full Heusler compound X 2 YZ [5,58,59], where X and Y are from transition metal elements and Z from main group elements. In both half and full Heusler alloys, they normally crystalize in a cubic structure yet with different configurations [60]: non-centrosymmetric cubic structure C1 b for half-Heusler; two different types for full Heusler: the Cu 2 MnAl structure with space group Fm3m, also known as L2 1 -type, and the Hg 2 CuTi structure with space ground F43m, also known as "inverse structure" or XA-type.…”