The document reports on an ab initio study of the electronic structure of Fe2MnZ (Z = Al, Si, Ge) Heusler alloys using density functional theory. The study finds that Fe2MnSi has 100% spin polarization and is half-metallic, while Fe2MnAl and Fe2MnGe exhibit metallic behavior with 93% and 98% spin polarization, respectively. The total magnetic moments of the alloys are consistent with the Slater-Pauling curve. The manganese atoms contribute the largest magnetic moments, while the Z element (Al, Si, Ge) contributes a negative magnetic moment less than 0.1 μB.

1. Ab initio study of Fe 2 MnZ (Al, Si, Ge) Heusler alloy using GGA approximation
Vivek Kumar Jain, Vishal Jain, N. Lakshmi, and K. Venugopalan
Citation: AIP Conference Proceedings 1591, 1130 (2014); doi: 10.1063/1.4872877
View online: http://dx.doi.org/10.1063/1.4872877
View Table of Contents: http://scitation.aip.org/content/aip/proceeding/aipcp/1591?ver=pdfcov
Published by the AIP Publishing
Articles you may be interested in
An ab-initio study of full Heusler alloy Fe 2 CoGa
AIP Conf. Proc. 1536, 805 (2013); 10.1063/1.4810472
Half-metallic properties for the Mn 2 Fe Z ( Z = Al , Ga, Si, Ge, Sb) Heusler alloys: A first-principles study
J. Appl. Phys. 103, 083908 (2008); 10.1063/1.2903057
Study on the structural relationship between the liquid and amorphous Fe 78 Si 9 B 13 alloys by ab initio
molecular dynamics simulation
Appl. Phys. Lett. 90, 201909 (2007); 10.1063/1.2737937
Structural characterization of the Co 2 Fe Z ( Z = Al , Si, Ga, and Ge) Heusler compounds by x-ray diffraction and
extended x-ray absorption fine structure spectroscopy
Appl. Phys. Lett. 90, 172501 (2007); 10.1063/1.2731314
175% tunnel magnetoresistance at room temperature and high thermal stability using Co 2 Fe Al 0.5 Si 0.5 full-
Heusler alloy electrodes
Appl. Phys. Lett. 89, 252508 (2006); 10.1063/1.2420793
This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
117.211.88.66 On: Wed, 30 Apr 2014 14:32:38

2. Ab Initio Study of Fe2MnZ (Al, Si, Ge) Heusler Alloy Using
GGA Approximation
Vivek Kumar Jain*
, Vishal Jain, N. Lakshmi and K. Venugopalan
Department of Physics, Mohanlal Sukhadia University, Udaipur-313001, India
*E-mail:vivek.jain129@gmail.com
Abstract. Density functional theory based on FP-LAPW method used to investigate the electronic structure of Fe2MnZ,
shows that the total spin magnetic moment shows a trend consistent with the Slater–Pauling curve. The Fe and Mn
magnetic moment depend on choice of Z element although the magnetic moment of Z element is negative and less than
0.1 µB. Spin polarization calculations evidence 100% spin polarization for Fe2MnSi. Fe2MnAl and Fe2MnGe show
metallic behavior with 93%, 98% spin polarization.
Keywords: Heusler alloy, electronic structure, half metallicity.
PACS: 71.20.-b, 31.15.A-, 75.50.Bb;
INTRODUCTION
In general, most of Heusler alloys have attracted
attention because of their unique properties like high
spin polarization, half-metallic ferromagnetism and
high Curie temperature. Also, most Fe-based full-
Heusler alloys with chemical formula Fe2MnZ have
been predicted to be half-metallic [1-2].
FIGURE 1. Crystal structure of the Fe2MnZ
Heusler compounds (Z=Al, Si, Ge).
Fe2MnZ , with Z belonging to the III and IV group,
are well known magnetic systems with a good
magnetic moment due to manganese atoms. In this
paper we have studied the effect of adding group III/
IV elements namely, Al, Si, and Ge at the Z site in
Fe2MnZ Heusler alloy.
COMPUTATIONAL DETAILS
Density functional theory (DFT), using full
potential-linearized augmented plane wave (FP-
LAPW) method by WIEN2k package [3], is used to
calculate the electronic structures of Fe2MnZ (Z= Al,
Si and Ge) compounds. We have used the exchange
correlation using the generalized gradient
approximation (GGA) functional by Perdew-Burke-
Ernzerhof (PBE-GGA, 96). The energy threshold
between the core and the valence states was set to
−6.0Ry and RMT × Kmax = 7 were used. The energy
convergence criterion was set to 10−4
Ry. Lattice
parameter has been optimized by volume optimization
using Murnaghon equation and values are listed in
Table 1. In the calculation, Fe2MnZ Heusler alloys are
considered to have L21 ordered structure as shown in
Figure 1. In this structure, Fe atoms are located at (1/4,
1/4, 1/4) and (3/4, 3/4, 3/4), Mn atoms at (1/2, 1/2, 1/2)
and Z atoms at (0, 0, 0) in the unit cell of Fm-3m space
group.
RESULTS AND DISCUSSION
The calculated DOS for Fe2MnZ (Z= Al, Si, Ge)
alloy with the L21 structure obtained using the PBE-
Solid State Physics
AIP Conf. Proc. 1591, 1130-1132 (2014); doi: 10.1063/1.4872877
© 2014 AIP Publishing LLC 978-0-7354-1225-5/$30.00
1130This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
117.211.88.66 On: Wed, 30 Apr 2014 14:32:38

3. GGA approaches, are shown in figure 2. Results show
that the contribution to the hybridized states is mainly
due to Fe and Mn 3d orbitals, which indicates a
covalent character of their interaction. The
contribution to the total DOS from the Z atom is small.
The electron spin polarization P at Fermi energy (Ef)
of a material is defined by [4]
( ) ( )
( ) ( )ff
ff
EE
EE
P
↓+↑
↓−↑
=
ρρ
ρρ
(1)
where, ρ↑(Ef) and ρ↓(Ef) are the majority and
minority density of state at the Ef.
-5
0
5
-5 0 5
-5
0
5
-10
-5
0
5
10
Fe2
MnSi
Fe2
MnGe
Energy(eV)
DOS(States/eV)
Fe2
MnAl
FIGURE 2. DOS for Fe2MnZ (Z = Al, Si, Ge).
The electrons at Ef are fully spin polarized (spin
polarization = 100%) when any one of the DOS i.e. ρ↑
or ρ↓ is equal to zero. According to this calculation
Fe2MnSi has 100% spin polarization. Fe2MnAl and
Fe2MnGe have 93% and 98% spin polarization
respectively. Thus Fe2MnSi has a half metallic
character. We have obtained a higher spin polarization
for Fe2MnAl and Fe2MnGe compared to reported
values of 81% and 96% respectively [4]. The obtained
magnetic moments of constituent atoms in Fe2MnZ (Z
= Al, Si, Ge) are listed in table 1.
According to Slater-Pauling curve (SPC) the
magnetic moment per unit cell in multiples of the Bohr
magneton (µB) is given by
24−= NMtotal (2)
where, N denotes valence electrons in the unit cell. For
Fe2MnZ (Z= Al, Si, Ge), there is a total of
2x8+7+3=26 valence electrons in the unit cell of
Fe2MnAl and 2x8+7+4=24 in the Fe2MnSi/Ge. For
this reason, the expected magnetic moment is 2µB for
Fe2MnAl and 3µB for Fe2MnSi/Ge. Calculated
magnetic moment is same as SPC for all. In Fe2MnZ,
the Mn contribution to the total magnetic moment is
large compared to Fe. It is observed that the Heusler
alloys of X2MnZ where X= Fe, Co or Ni, the Mn
atoms fully occupied the B-sites leading to an indirect
d-d coupling achieved by conduction electrons making
the Mn atoms ferromagnetically coupled resulting in a
large magnetic moment.
In conclusion, ab initio calculations suggest that
Fe2MnSi have half metallic with 100% spin
polarization, Fe2MnAl and Fe2MnGe exhibits metallic
behavior with 93% and 98% spin polarization. The
total DOS shows that each compound has an energy
gap near the Fermi energy in the minority spin state.
ACKNOWLEDGMENTS
The work has been supported by UGC DSA and
DST-FIST schemes of the Department of Physics, M L
Sukhadia University, Udaipur. Vivek Kumar Jain and
Vishal Jain gratefully acknowledge support from
UGC-BSR and UGC-DAE CRS Research
Fellowships.
REFERENCES
[1] I. Galanakis, P. H. Dederichs and N. Papanikolaou,
Phys. Rev. B 66, 174429 (2002).
[2] L. Hongzhi, Z. Zhiyong, M. Li, X. Shifeng,
L. Heyan, Q. Jingping, L. Yangxian, and
W. Guangheng. J. Phys. D: Appl. Phys. 40, 7121-
TABLE 1. Magnetic parameters of Fe2MnZ Heusler Compounds
Sample Lattice parameter (Å) Total magnetic moment (µB) 2Fe (µB) Mn (µB) Z (Al/Si/Ge) (µB)
Fe2MnAl 5.6792 2.019 -0.270 2.296 -0.007
Fe2MnSi 5.6586 3.008 0.425 2.594 -0.011
Fe2MnGe 5.6827 3.022 0.421 2.617 -0.016
1131This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
117.211.88.66 On: Wed, 30 Apr 2014 14:32:38

4. 7127 (2010).
[3] P. Blaha, K. Schwarz, P. Sorantin and S. B. Tricky,
Comput. Phys. Commun. 59, 399-415. (1990).
[4] S. M. Azar, B. A. Hamad and J. M. Khalifeh.
J. Magn. Magn. Mater. 324, 1776–1785 (2012).
1132This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP:
117.211.88.66 On: Wed, 30 Apr 2014 14:32:38