Above-room-temperature ferromagnetism in half-metallic Heusler compounds NiCrP, NiCrSe, NiCrTe, and NiVAs: A first-principles study

Abstract

We study the interatomic exchange interactions and Curie temperatures in half-metallic semi Heusler compounds NiCrZ (Z=P, Se, Te) and NiVAs. The study is performed within the framework of density functional theory. The calculation of exchange parameters is based on the frozen-magnon approach. It is shown that the exchange interactions in NiCrZ vary strongly depending on the Z constituent. The Curie temperature, Tc, is calculated within the mean field and random phase approximations. The difference between two estimations is related to the properties of the exchange interactions. The predicted Curie temperatures of all four systems are considerably higher than room temperature. The relation between the half-metallicity and the value of the Curie temperature is discussed. The combination of a high spin-polarization of charge carriers and a high Curie temperature makes these Heusler alloys interesting candidates for spintronics applications.

Ab initio electronic and magnetic properties of half-metallic NiCrSi and NiMnSi Heusler alloys: The role of defects and interfaces

“…Finally, the effect of stress on the magnetic anisotropy of thin NiMnSb films and the role of defects have been explored. 63,64 Based on the success of first-principles electronic structure calculations to describe the properties of NiMnSb, several authors have predicted new half-metallic Heusler alloys crystallizing in the C1 b structure of semi-Heusler compounds like NiCrM and NiVM (M= P, As, Sb, S, Se and Te), 65,66,67 and XCrAl (X= Fe, Co, Ni) and NiCrZ (Z= Al, Ga, In). 68 Recently, Katayama-Yoshida and collaborators published a paper including also ab-initio calculations on NiMnSi semi-Heusler alloy, which was predicted to have a Curie temperature of 1050 K, 69 exceeding even the 730 K shown by NiMnSb.…”

First-principles calculations of exchange interactions, spin waves, and temperature dependence of magnetization in inverse-Heusler-based spin gapless semiconductors

“…Actually, the critical temperature is given by the average value of the magnon energies which in MFA is the arithmetic average taking all the magnon values with equal weight. Thus is an arithmetic property that the MFA estimation is larger than experimental values [58][59][60] . The MFA expression of the critical temperature for a multi-sublattice material like Heusler compounds has been provided in literature.…”

“…In reality low-energy magnons have more weight in determining the critical temperature and MFA usually overestimates experimental data by more than 20%. [58][59][60] The Monte-Carlo determined critical temperature does not suffer from this drawback and thus it is expected to approach the experimental values of the critical temperature.…”

New Ferromagnetic Nitrides, CaN and SrN, and their “Recipe”

“…Some designed materials were synthesized by experiments. The success of ZB-CrAs attracted many theorists to carry out similar studies [8][9][10][11][12][13][14][15][16]. This was designed by Shirai [6] and was synthesized by Akinaga et al [7].…”