Strain Conditions for the Inverse Heusler Type Fully Compensated Spin-Gapless Semiconductor Ti2MnAl: A First-Principles Study

Abstract

In this work, we systematically studied the structural, electronic, magnetic, mechanical and thermodynamic properties of the fully compensated spin-gapless inverse Heusler Ti2MnAl compound under pressure strain condition by applying the first-principles calculation based on density functional theory and the quasi-harmonic Debye model. The obtained structural, electronic and magnetic behaviors without pressure are well consistent with previous studies. It is found that the spin-gapless characteristic is destroyed at 20 GPa and then restored with further increase in pressure. While, the fully compensated ferromagnetism shows a better resistance against the pressure up to 30 GPa and then becomes to non-magnetism at higher pressure. Tetragonal distortion has also been investigated and it is found the spin-gapless property is only destroyed when c/a is less than 1 at 95% volume. Three independent elastic constants and various moduli have been calculated and they all show increasing tendency with pressure increase. Additionally, the pressure effects on the thermodynamic properties under different temperature have been studied, including the normalized volume, thermal expansion coefficient, heat capacity at constant volume, Grüneisen constant and Debye temperature. Overall, this theoretical study presents a detailed analysis of the physical properties’ variation under strain condition from different aspects on Ti2MnAl and, thus, can provide a helpful reference for the future work and even inspire some new studies and lead to some insight on the application of this material.

Structural, Electronic, Magnetic, Mechanic and Thermodynamic Properties of the Inverse Heusler Alloy Ti2NiIn Under Pressure

“…Normally, the Heusler compounds crystallize in a highly ordered cubic structure either in Cu 2 MnAl-type or Hg 2 CuTi-type, and there is half metallic behavior found in both types. We should point out here that Hg 2 CuTi-type full Heusler alloys have been widely studied and a number of this type alloys exhibit half-metallic properties [18][19][20], and also, many of Hg 2 CuTi alloys obey the well-known Slater-Pauling rule [21][22][23]. More important, some Hg 2 CuTi-type Ti 2 -based full Heusler alloys have been predicted to be spin-gapless semiconductors [18,24] or magnetic Weyl semimetal [25].…”

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

“…The family of Heusler alloys has attracted much scientific attention and research interest during recent years, and their various and special functionalities have been extensively studied and explored in many different areas. The ferromagnetism was firstly observed in Heusler compounds with no ferromagnetic elements and, afterwards, many more new properties have been found, such as half metallicity [1][2][3][4][5][6][7][8][9][10], spin gapless semiconductivity [11][12][13][14][15][16][17], thermoelectricity [18][19][20][21][22][23], superconductivity [24][25][26], and topological insulativity [27,28]. Also, these properties can be easily tuned by simple element substitution within the periodic table.…”

Theoretical Study of the Electronic, Magnetic, Mechanical and Thermodynamic Properties of the Spin Gapless Semiconductor CoFeMnSi

“…Since the discovery of spin-gapless semiconductors (SGS) from a theoretical approach by Wang, et al [1], they immediately became interesting for the development of spintronics and magnetoelectronics [2][3][4][5][6][7][8][9][10][11][12][13]. The electronic band structure of SGS is completely spin-polarized; in one spin channel, a small band gap is present at the Fermi level, similar to in a semiconductor; whereas, in the other spin channel, the valence band maximum contacts the conduction band minimum at the Fermi level, resulting into an exactly zero gap.…”

“…Among different research directions for SGSs of different structures and different components, the Heusler alloy families are particularly interesting because there are not only many theoretical calculations showing the electronic band feature of SGSs in Heusler alloys, such as Ti 2 MnAl [2,12,[15][16][17], Ti 2 CoSi [5], Ti 2 Vas [5], Zr 2 MnAl [18,19], Zr 2 MnGa [18,20] and Cr 2 ZnSi [13,21,22], but also, a few experimental syntheses and measurements confirming the presence of the spin-gapless semiconducting behaviors, such as Mn 2 CoAl [14], Ti 2 MnAl [2]. Conventionally, Heusler compounds represent a huge family of intermetallic alloys and they can be mainly divided into two groups [23,24]: full-Heusler with general formula X 2 YZ and half-Heusler with general formula XYZ, in which Z is an sp main group element and X and Y are the transition metal elements.…”

“…Consequently, various Heusler compounds can be simply designed by substituting with an element from the same group in the periodic table. For a full-Heusler alloy, when the highly ordered cubic structure is considered under normal conditions, there are two typical structural configurations [12,25]: the first one is the Cu 2 MnAl-type, also known as the L2 1 structure; the second one is the Hg 2 CuTi-type, also known as the XA structure.…”