Structural, electronic, magnetic, and transport properties of the equiatomic quaternary Heusler alloy CoRhMnGe: Theory and experiment

Abstract

In this work, we present structural, electronic, magnetic, mechanical and transport properties of equiatomic quaternary Heusler alloy, CoRhMnGe using both theoretical and experimental techniques. A detailed structural analysis is performed using X-ray diffraction(XRD) and extended X-ray absorption fine structure(EXAFS) spectroscopy. The alloy is found to crystallize in Y-type structure having space group F43m (# 216). The ab-initio simulation pedict half-metallic ferromagnetic characteristics leading to large spin polarization. The calculated magnetization is found to be in fair agreement with experiment as well as those predicted by the Slater-Pauling rule, which is a prerequisite for half-metallicity. The magnetic transition temperature(TC) is found to be ∼ 760 K. Measured electrical resistivity in the temperature range 2-400 K also gives an indication of half-metallic behavior. Simulated resistivity matches fairly well with those measured, with the temperature dependant carrier relaxation time lying in the range 1 − 2 fs. Effect of hydrostatic pressure on electronic structure, magnetic and mechanical properties are investigated in detail. The alloy is found to preserve half-metallic characteristics upto 30.27 GPa beyond which it transit to metallic phase. No magnetic phase transition is found to occur in the whole range of pressure. The system also satisfies the Born-Huang criteria for mechanical stability upto a limited range of pressure. All these properties make CoRhMnGe alloy promising for spintronics devices.

Experimental and theoretical investigation on the possible half-metallic behaviour of equiatomic quaternary Heusler alloys: CoRuMnGe and CoRuVZ (Z = Al, Ga)

“…2% extra Mn was taken to compensate the weight loss due to Mn evaporation during melting. [13] For better homogeneity the ingots formed were flipped and melted several times . After melting, the samples were sealed in a quartz tube and annealed for 7 days at 1073 K followed by furnace cooling.…”

“…[9][10][11] There are a large number of reports on 3d-transition elements based quaternary Heusler alloys, but only a few 4d -based (Ru and Rh based) equiatomic quaternary * aftab@phy.iitb.ac.in Heusler alloys have been studied experimentally. [12][13][14] It would be interesting to see the effect of replacing one of the 3d-element by a 4d-element in quaternary Heusler alloys. For example, CoFeMnGe alloy was found to have considerable amount of DO 3 disorder[15] and replacing Fe by a 4d element (Rh and Ru) is expected to improve the structure, as both CoRuMnGe and CoRhMnGe [13] are found to crystallize in L2 1 structure.…”

Exploration of highly correlated Co‐based quaternary Heusler alloys for spintronics and thermoelectric applications

“…13,14 A large number of Heusler alloys are predicted to demonstrate half-metallic nature, which is further confirmed by experimentalists. 25 Impressed by the novel features of QHA here, we investigate experimentally not yet synthesized CoXMnAs (X = Ru, Rh) alloys for the first time. These alloys crystallize in L2 1 -type structure.…”

“…CoRhMnGe later on show T C of 760 K, which is much higher than previously reported alloys. 25 Impressed by the novel features of QHA here, we investigate experimentally not yet synthesized CoXMnAs (X = Ru, Rh) alloys for the first time. The theme of the current study is to explore the structural and mechanical stability along with magneto-electronic, transport and thermodynamic properties of titled alloys.…”

Half-metallic ferromagnetism and Ru-induced localization in quaternary Heusler alloy CoRuMnSi

“…It is also well-known 2,16 that, to minimize the disorder, the element of the octahedral site should be less electronegative than that at the tetrahedral site. A large number of Heusler alloys which show a considerable amount of disorder, e.g., CoFeMnGe, 17 CoFeMnSi, 1 MnCrVAl, 18 CrVTiAl 6 etc., have more than one element with nearly equal (small) electronegativity, and hence compete to occupy the octahedral site. Thus, if the elements with similar electronegativity values are the constituents of a Heusler alloy, it results in disorder.…”