The electronic band structure of ordered equiatomic compounds of 3d transition elements (Mn, Fe, Co, Ni) with nonmagnetic 4d and 5d elements (Rh, Pd, Pt, Ir) are investigated by linear muffin-tin orbital calculations. The systematic study considers 3d and 4d/5d spin moments and interatomic exchange interactions, with emphasis on the comparison between ferromagnetic and antiferromagnetic order. Total and site-resolved exchange interactions are calculated from first principles, and the obtained exchange constants are used to estimate ordering temperatures on a mean-field level

Kashyap, Arti

Sellmyer, David J.

Skomski, Ralph

Solanki, Ashok K.

Xu, Yinfan

English

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University of Nebraska - Lincoln 
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David Sellmyer Publications Research Papers in Physics and Astronomy 
6-1-2004 
Magnetism of L10 compounds with the composition MT (M = Rh, 
Pd, Pt, Ir and T = Mn, Fe, Co, Ni) 
Arti Kashyap 
University of Nebraska-Lincoln, akashyap@lnmiit.ac.in 
Ralph Skomski 
University of Nebraska-Lincoln, rskomski2@unl.edu 
Ashok K. Solanki 
University of Nebraska - Lincoln, asolanki2@unl.edu 
Yinfan Xu 
University of Nebraska - Lincoln, yxu2@unl.edu 
David J. Sellmyer 
University of Nebraska-Lincoln, dsellmyer@unl.edu 
Follow this and additional works at: https://digitalcommons.unl.edu/physicssellmyer 
 Part of the Physics Commons 
Kashyap, Arti; Skomski, Ralph; Solanki, Ashok K.; Xu, Yinfan; and Sellmyer, David J., "Magnetism of L10 
compounds with the composition MT (M = Rh, Pd, Pt, Ir and T = Mn, Fe, Co, Ni)" (2004). David Sellmyer 
Publications. 26. 
https://digitalcommons.unl.edu/physicssellmyer/26 
This Article is brought to you for free and open access by the Research Papers in Physics and Astronomy at 
DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in David Sellmyer Publications 
by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. 
Magnetism of L10 compounds with the composition
MT „MÄRh, Pd, Pt, Ir and TÄMn, Fe, Co, Ni …a…
A. Kashyap, R. Skomski, A. K. Solanki, Y. F. Xu, and D. J. Sellmyer
Department of Physics and Astronomy, and Center for Materials Research and Analysis,
University of Nebraska, Lincoln, Nebraska 68588
~Presented on 9 January 2004!
The electronic band structure of ordered equiatomic compounds of 3d transition elements~Mn, Fe,
Co, Ni! with nonmagnetic 4d and 5d elements~Rh, Pd, Pt, Ir! are investigated by linear muffin-tin
orbital calculations. The systematic study considers 3d and 4d/5d spin moments and interatomic
exchange interactions, with emphasis on the comparison between ferromagnetic and
antiferromagnetic order. Total and site-resolved exchange interactions are calculated from first
principles, and the obtained exchange constants are used to estimate ordering temperatures on a
mean-field level. ©2004 American Institute of Physics.@DOI: 10.1063/1.1687631#
I. INTRODUCTION
Equiatomic magnetic compounds crystallizing in the te-
tragonalL10 phase have attracted much attention as perma-
nent magnets and in magnetic recording.1–7 These com-
pounds are of fundamental interest for their high uniaxial
anisotropy to about 107 MJ/m3, which results from their
natural superlattice structure, and CoPt was the first true
permanent-magnet alloy. In addition,L10 nanoclusters have
high potential as cluster-assembled granular films for
1 Tb/in.2 perpendicular recording media. Exchange interac-
tions in the compounds are important because they determine
the zero- and finite-temperature properties such as magnetic
order, finite-temperature anisotropy affecting, for example,
domain formation and spin-flop transitions.
The tetragonalL10 intermetallics have the general struc-
ture MT, whereM is an iron-series (3d) transition metal
and T is a 4d or 5d transition metal. Many intermetallics
whereM5Fe or Co are ferromagnetic~FM!, although anti-
ferromagnetism ~AFM! may be possible in some Fe-
containing compounds.8 L10 intermetallics whereM5Mn
are typically AFM, which reflects a general trend towards
AFM due to half-filled 3d shells. Concerning first-principles
calculations onL10 magnets, Ravindranet al.
9 calculated the
magnetocrystalline anisotropy of someL10 compounds. This
research was preceeded by earlier calculations on various
3d-4d/5d multilayers,10 which contain theL10 structure as a
special case. Moruzzi and Marcus,11 discussed structural ef-
fects on magnetic properties of FeRh and FePd by first-
principles total-energy calculations. Garciaet al.12 obtained
the magnetocrystalline anisotropy of FePd, and there are Cu-
rie temperature (TC) calculations for FePt in a B2O3 matrix.
3
However, compared to Cu3Au and other related
structures,13,14 little work has been done onL10 compounds
made from elements other than Fe, Co, Pd, and Pt.
II. METHOD OF CALCULATIONS
To perform the self-consistent, spin-polarized electronic
structure calculations, the linear muffin-tin orbital~LMTO!
method within the atomic sphere approximation15 is used.
The calculations are performed for 288k points, and the
Barth-Hedin exchange-correlation potential was employed.
The local spin-up and spin-down densities of states and mag-
netic moments are calculated using the linearized tetrahedron
method. A minimal basis set consisting of ofs, p, and d
orbitals is used for both types of atoms and the spin-orbit
coupling is not included in our calculations. Due to the dif-
ferent sizes of the constituent atoms it is necessary to assume
different Wigner-Seitz~WS! cell radii, but the ratio of WS
radii is kept to be the same as in their elemental form. Ex-
perimental data for the lattice parameters for all the com-
pounds are taken from Ref. 16. One example is that, for FePt
compound, WS values are 2.709 a.u. and 2.947 a.u. for Fe
and Pt, respecively. TheL10 structure can be understood as
alternate layers ofM ~Mn, Fe, Co, Ni! andT ~Rh, Pd, Ir, Pt!
atoms with eachM atom surrounded by eightT atoms and
four M atoms as nearest neighbors. The unit cell contains
four atoms but can be considered as simple tetragonal cell
with two atoms. The interatomic exchange interactions (Ji j )
are calculated in the Heisenberg approximation. Details of
the method can be found elsewhere.17 The total exchange
parameter (J0) reflects the energy change due to small-angle
rotation of the moment at one site. In contrast to theJi j , it is
given by site-diagonal scattering matrix~or Green function!,
wherei 5 j . Using J0 , transition temperatures are estimated
within mean-field theory, using the relationTC52/3kB ^J0&
(TN52TC).
III. RESULTS AND DISCUSSION
Table I shows self-consistent magnetic moments for all
investigated compounds. The results are in agreement with
all other calculations and with the available experimental
data. Table II shows the calculatedJ0 and calculated mean-
field ordering temperature along with some available experi-
mental data.18 As expected, theTC is overestimated by thea!No proof corrections received from author prior to publication.
JOURNAL OF APPLIED PHYSICS VOLUME 95, NUMBER 11 1 JUNE 2004
74800021-8979/2004/95(11)/7480/3/$22.00 © 2004 American Institute of Physics
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TABLE I. Magnetic moments (mB /f.u.) in the form ofmtotal5mT1mM . Experimental values are quoted in
parentheses.
Mn Fe Co Ni
Rh 3.01052.97810.022 2.23852.21410.022 1.32151.11910.102 0
Pd 4.13853.84510.293 3.29952.95210.347 2.28151.90210.379 1.01350.73210.281
(4.410.0) (2.8510.35) (1.9710.35) (mavg /atom50.55)
Ir 1.11651.22220.006 1.90951.92420.015 0.89850.80010.098 0
Pt 4.02253.66710.355 3.265 2.91610.349 2.25451.83710.417 0
(4.310.0) „2.801(20.25)… (1.6010.25)
TABLE II. Total exchange parameterJ0 (mRy5156 K) for M and T sites and Curie temperature~K! along
with experimental values given in parentheses.
J0 TC
Mn Fe Co Ni Mn Fe Co Ni
Rh M 217.883 3.024 2.863 1850~200! 347 355
T 0.277 0.273 0.512
Pd M 214.256 9.543 9.696 1.974 1285~ 10! 1270~700! 1284 310
T 2.045 2.529 2.506 0.956
Ir M 22.367 3.436 1.861 240 377 217
T 0.092 0.149 0.199
Pt M 215.008 8.338 8.766 1318~970! 1128~750! 1186~850!
T 2.482 2.371 2.506
TABLE III. Site-resolved exchange interaction parameters~mRy! for the FM and AFM configurations. The
table shows theM -M (J11 ,J13) andM -T (J12 ,J14) pairs and the number of neighbors with increasing inter-
atomic distance.
J ~FM! Mn Fe Co Ni J ~AFM! Mn Fe Co Ni
Rh J12(8) 0.041 0.034 0.051 J12(4) 0 0.003 0.001
J11(4) 24.550 0.657 0.481 J14(4) 0 0 0
J11(2) 0.694 0.792 0.148 J11(4) 23.322 20.157 0.806
J11(4) 20.293 0.054 20.043 J13(2) 0.010 20.008 0.002
J11(8) 20.400 20.036 0.133 J11(4) 20.587 0.253 20.096
J12(8) 0.041 0.034 0.051 J13(8) 0.001 0.004 0.003
J11(8) 0.468 20.124 20.155 J14(4) 0 0 0
J12(4) 0 0.003 0.014
J13(8) 20.246 0.333 0.134
Pd J12(8) 0.227 0.234 0.205 0.073 J12(4) 20.093 0.004 0.012 0.030
J11(4) 24.331 0.533 1.605 0.241 J14(4) 0 0 0 0
J11(2) 1.691 0.090 20.127 20.064 J11(4) 24.951 1.361 1.775 0.172
J11(4) 0.042 0.952 0.120 0.038 J13(2) 0 0.010 0.004 0
J11(8) 20.223 0.205 0.234 0 J11(4) 0.015 0.401 0.220 0.030
J12(8) 0.277 20.234 0.205 0.073 J13(8) 0 0 20.005 0
J11(8) 20.230 0.234 20.125 J14(4) 0 0 0 0
J12(4) 20.093 0.004 0.012 0.030
J13(8) 0.098 0.318 0.174 20.026
Ir J12(8) 0.005 0.0156 0.014 J12(4) 0.001 0 0.003
J11(4) 21.129 0.748 0.319 J14(4) 0 0 0
J11(2) 0.080 0.502 0.095 J11(4) 21.035 0.071 0.404
J11(4) 0.204 20.116 20.038 J13(2) 0.003 20.010 0.002
J11(8) 20.109 0.067 0.084 J11(4) 0.291 20.065 20.068
J12(8) 0.006 0.016 0.014 J13(8) 0.001 20.001 0.001
J11(8) 0.097 20.048 20.087 J14(4) 0 0 0
J12(4) 0.001 0 0.003
J13(8) 20.133 0.235 0.057
Pt J12(8) 0.264 0.239 0.226 J12(4) 0.013 0.009 0
J11(4) 23.188 0.787 1.305 J14(4) 0 0 0
J11(2) 2.650 0.056 20.053 J11(4) 24.847 1.884 1.312
J11(4) 20.602 0.711 0.038 J13(2) 20.025 0.017 0.001
J11(8) 20.357 0.253 0.267 J11(4) 0.126 20.052 0.113
J12(8) 0.263 0.239 0.226 J13(8) 0.004 20.001 20.004
J11(8) 20.552 20.400 20.235 J14(4) 0 0 0
J12(4) 0.013 0.008 0
J13(8) 0.377 0.491 0.302
7481J. Appl. Phys., Vol. 95, No. 11, Part 2, 1 June 2004 Kashyap et al.
Downloaded 14 Nov 2006 to 129.93.16.206. Redistribution subject to AIP license or copyright, see http://jap.aip.org/jap/copyright.jsp
above simple mean-field expression. OurJ0 values are nega-
tive for Mn compounds suggesting the AFM order to be
more stable in MnRh, MnPd, MnIr, and MnPt. For the com-
pounds of Fe and Co,J0 calculations suggest FM ordering at
equilibrium lattice parameters. Compounds of Ni with Rh, Ir,
and Pt are paramagnetic~PM! at equilibrium lattice param-
eters, in accordance with the experimental data.18 However,
the strain dependence of the spin structure may yield transi-
tions to a FM state, for example due to embbeding of nano-
particles in a matrix. Further experimental complications are
coexistent phases, such as disordered fcc. Table III shows
site-resolved exchange interaction parameters@(Ji j )s# for all
for the FM and AFM configurations. Nearest neighbors
around the magnetic 3d transition element~Mn, Fe, Co, Ni!
are also given upto a distance of nearly twice the lattice
parameter.J11 andJ13 indicate exchange betweenM atoms
and J12 and J14 indicate exchange betweenM -T atoms. As
evident from the data in Table III, all Mn compounds exhibit
pronounced negative exchange interactions between four
Mn-Mn first nearest pairs,J11(4), indicating that the Mn
spins in a given plane would prefer to align antiferromagneti-
cally, trying to form an intraplane checkerboard pattern in
addition to the AFM interlayer coupling. In all Fe and Co
compounds, FM ordering is more favorable, whereas the Ni
compounds are PM, with the exception of the ferromagnetic
NiPd.
IV. CONCLUSIONS
We have performed first-principles calculations forL10
compounds of Mn, Fe, Co with Rh, Pd, Pt, Ir. The obtained
moments and exchange coupling constants are then used to
discuss the spin structure of the intermetallics and to estimate
the ordering temperature. As expected from band-filling ar-
guments, there is a trend from ferromagnetism to antiferro-
magnetism when going from late 3d elements towards the
middle of the series. However, for some compounds the en-
ergy differences are small and strain or doping may stabilize
the FM phase.
ACKNOWLEDGMENTS
This research was supported by AFOSR, DOE, NSF
MRSEC, by the Keck foundation, and by CMRA. The au-
thors would like to acknowledge helpful discussions with
Professor S. S. Jaswal and Professor R. F. Sabirianov. A.K.S.
is thankful to MNIT, Jaipur for granting leave.
1D. J. Sellmyer, Nature~London! 420, 374 ~2002!.
2Cohesion in Metals: Transition Metal Alloys, edited by F. R. de Boer
~North-Holland, Amsterdam, 1988!.
3H. Zeng, R. F. Sabirianov, O. Mryasov, M. L. Yan, K. Cho, and D. J.
Sellmyer, Phys. Rev. B66, 184425~2002!.
4T. Klemmer, D. Hoydick, H. Okumura, B. Zhang, and W. A. Soffa, Scr.
Metall. Mater.33, 1793~1995!.
5Y. Shao, M. L. Yan, and D. J. Sellmyer, J. Appl. Phys.93, 8152~2003!.
6R. Skomski, J. Phys.: Condens. Matter15, R841~2003!.
7R. Skomski, A. Kashyap, and D. J. Sellmyer, IEEE Trans. Magn.39, 2917
~2003!.
8G. Brown, B. Kraczek, A. Janotti, T. C. Schulthess, G. M. Stocks, and D.
D. Johnson, Phys. Rev. B68, 052405~2003!.
9P. Ravindran, A. Kjekshus, H. Fjellvag, P. James, L. Nordstrom, B. Jo-
hansson, and O. Eriksson, Phys. Rev. B63, 144409~2001!.
10M. T. Johnson, P. J. H. Bloemen, F. J. A. den Broeder, and J. J. de Vries,
Rep. Prog. Phys.59, 1409~1996!.
11V. L. Moruzzi and P. M. Marcus, Phys. Rev. B48, 16 106~1993!.
12D. Garcia, R. Casero, M. Vazquez, and A. Hernando, Phys. Rev. B63,
104421~2001!.
13A. Sakuma, Phys. Rev. B67, 024420~2003!.
14A. Kashyap, A. K. Solanki, T. Nautiyal, and S. Auluck, Phys. Rev. B52,
13 471~1995!.
15O. K. Andersen, Phys. Rev. B8, 3060~1975!.
16P. Villars and L. D. Calvert,Pearsons Handbook of Crystallographic Data
for Intermetallic Phases~American Society of Metals, Metals Park, OH,
1985!.
17A. I. Liechtenstein, M. I. Katsnelson, V. P. Antropov, and V. A. Gubanov,
J. Magn. Magn. Mater.57, 65 ~1988!.
18H. P. J. Wijn,Data in Science and Technology~Springer, Berlin, 1991!.
7482 J. Appl. Phys., Vol. 95, No. 11, Part 2, 1 June 2004 Kashyap et al.
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Magnetism of \u3ci\u3eL\u3c/i\u3e1\u3csub\u3e0\u3c/sub\u3e compounds with the composition \u3ci\u3eMT\u3c/i\u3e (\u3ci\u3eM\u3c/i\u3e = Rh, Pd, Pt, Ir and \u3ci\u3eT\u3c/i\u3e = Mn, Fe, Co, Ni)

DigitalCommons@University of Nebraska

University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln David Sellmyer Publications Research Papers in Physics and Astronomy 6-1-2004 Magnetism of L10 compounds with the composition MT (M = Rh, Pd, Pt, Ir and T = Mn, Fe, Co, Ni) Arti Kashyap University of Nebraska-Lincoln, akashyap@lnmiit.ac.in Ralph Skomski University of Nebraska-Lincoln, rskomski2@unl.edu Ashok K. Solanki University of Nebraska - Lincoln, asolanki2@unl.edu Yinfan Xu University of Nebraska - Lincoln, yxu2@unl.edu David J. Sellmyer University of Nebraska-Lincoln, dsellmyer@unl.edu Follow this and additional works at: https://digitalcommons.unl.edu/physicssellmyer  Part of the Physics Commons Kashyap, Arti; Skomski, Ralph; Solanki, Ashok K.; Xu, Yinfan; and Sellmyer, David J., "Magnetism of L10 compounds with the composition MT (M = Rh, Pd, Pt, Ir and T = Mn, Fe, Co, Ni)" (2004). David Sellmyer Publications. 26. https://digitalcommons.unl.edu/physicssellmyer/26 This Article is brought to you for free and open access by the Research Papers in Physics and Astronomy at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in David Sellmyer Publications by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Magnetism of L10 compounds with the compositionMT „MÄRh, Pd, Pt, Ir and TÄMn, Fe, Co, Ni …a…A. Kashyap, R. Skomski, A. K. Solanki, Y. F. Xu, and D. J. SellmyerDepartment of Physics and Astronomy, and Center for Materials Research and Analysis,University of Nebraska, Lincoln, Nebraska 68588~Presented on 9 January 2004!The electronic band structure of ordered equiatomic compounds of 3d transition elements~Mn, Fe,Co, Ni! with nonmagnetic 4d and 5d elements~Rh, Pd, Pt, Ir! are investigated by linear muffin-tinorbital calculations. The systematic study considers 3d and 4d/5d spin moments and interatomicexchange interactions, with emphasis on the comparison between ferromagnetic andantiferromagnetic order. Total and site-resolved exchange interactions are calculated from firstprinciples, and the obtained exchange constants are used to estimate ordering temperatures on amean-field level. ©2004 American Institute of Physics.@DOI: 10.1063/1.1687631#I. INTRODUCTIONEquiatomic magnetic compounds crystallizing in the te-tragonalL10 phase have attracted much attention as perma-nent magnets and in magnetic recording.1–7 These com-pounds are of fundamental interest for their high uniaxialanisotropy to about 107 MJ/m3, which results from theirnatural superlattice structure, and CoPt was the first truepermanent-magnet alloy. In addition,L10 nanoclusters havehigh potential as cluster-assembled granular films for1 Tb/in.2 perpendicular recording media. Exchange interac-tions in the compounds are important because they determinethe zero- and finite-temperature properties such as magneticorder, finite-temperature anisotropy affecting, for example,domain formation and spin-flop transitions.The tetragonalL10 intermetallics have the general struc-ture MT, whereM is an iron-series (3d) transition metaland T is a 4d or 5d transition metal. Many intermetallicswhereM5Fe or Co are ferromagnetic~FM!, although anti-ferromagnetism ~AFM! may be possible in some Fe-containing compounds.8 L10 intermetallics whereM5Mnare typically AFM, which reflects a general trend towardsAFM due to half-filled 3d shells. Concerning first-principlescalculations onL10 magnets, Ravindranet al.9 calculated themagnetocrystalline anisotropy of someL10 compounds. Thisresearch was preceeded by earlier calculations on various3d-4d/5d multilayers,10 which contain theL10 structure as aspecial case. Moruzzi and Marcus,11 discussed structural ef-fects on magnetic properties of FeRh and FePd by first-principles total-energy calculations. Garciaet al.12 obtainedthe magnetocrystalline anisotropy of FePd, and there are Cu-rie temperature (TC) calculations for FePt in a B2O3 matrix.3However, compared to Cu3Au and other relatedstructures,13,14 little work has been done onL10 compoundsmade from elements other than Fe, Co, Pd, and Pt.II. METHOD OF CALCULATIONSTo perform the self-consistent, spin-polarized electronicstructure calculations, the linear muffin-tin orbital~LMTO!method within the atomic sphere approximation15 is used.The calculations are performed for 288k points, and theBarth-Hedin exchange-correlation potential was employed.The local spin-up and spin-down densities of states and mag-netic moments are calculated using the linearized tetrahedronmethod. A minimal basis set consisting of ofs, p, and dorbitals is used for both types of atoms and the spin-orbitcoupling is not included in our calculations. Due to the dif-ferent sizes of the constituent atoms it is necessary to assumedifferent Wigner-Seitz~WS! cell radii, but the ratio of WSradii is kept to be the same as in their elemental form. Ex-perimental data for the lattice parameters for all the com-pounds are taken from Ref. 16. One example is that, for FePtcompound, WS values are 2.709 a.u. and 2.947 a.u. for Feand Pt, respecively. TheL10 structure can be understood asalternate layers ofM ~Mn, Fe, Co, Ni! andT ~Rh, Pd, Ir, Pt!atoms with eachM atom surrounded by eightT atoms andfour M atoms as nearest neighbors. The unit cell containsfour atoms but can be considered as simple tetragonal cellwith two atoms. The interatomic exchange interactions (Ji j )are calculated in the Heisenberg approximation. Details ofthe method can be found elsewhere.17 The total exchangeparameter (J0) reflects the energy change due to small-anglerotation of the moment at one site. In contrast to theJi j , it isgiven by site-diagonal scattering matrix~or Green function!,wherei 5 j . Using J0 , transition temperatures are estimatedwithin mean-field theory, using the relationTC52/3kB ^J0&(TN52TC).III. RESULTS AND DISCUSSIONTable I shows self-consistent magnetic moments for allinvestigated compounds. The results are in agreement withall other calculations and with the available experimentaldata. Table II shows the calculatedJ0 and calculated mean-field ordering temperature along with some available experi-mental data.18 As expected, theTC is overestimated by thea!No proof corrections received from author prior to publication.JOURNAL OF APPLIED PHYSICS VOLUME 95, NUMBER 11 1 JUNE 200474800021-8979/2004/95(11)/7480/3/$22.00 © 2004 American Institute of PhysicsDownloaded 14 Nov 2006 to 129.93.16.206. Redistribution subject to AIP license or copyright, see http://jap.aip.org/jap/copyright.jspTABLE I. Magnetic moments (mB /f.u.) in the form ofmtotal5mT1mM . Experimental values are quoted inparentheses.Mn Fe Co NiRh 3.01052.97810.022 2.23852.21410.022 1.32151.11910.102 0Pd 4.13853.84510.293 3.29952.95210.347 2.28151.90210.379 1.01350.73210.281(4.410.0) (2.8510.35) (1.9710.35) (mavg /atom50.55)Ir 1.11651.22220.006 1.90951.92420.015 0.89850.80010.098 0Pt 4.02253.66710.355 3.265 2.91610.349 2.25451.83710.417 0(4.310.0) „2.801(20.25)… (1.6010.25)TABLE II. Total exchange parameterJ0 (mRy5156 K) for M and T sites and Curie temperature~K! alongwith experimental values given in parentheses.J0 TCMn Fe Co Ni Mn Fe Co NiRh M 217.883 3.024 2.863 1850~200! 347 355T 0.277 0.273 0.512Pd M 214.256 9.543 9.696 1.974 1285~ 10! 1270~700! 1284 310T 2.045 2.529 2.506 0.956Ir M 22.367 3.436 1.861 240 377 217T 0.092 0.149 0.199Pt M 215.008 8.338 8.766 1318~970! 1128~750! 1186~850!T 2.482 2.371 2.506TABLE III. Site-resolved exchange interaction parameters~mRy! for the FM and AFM configurations. Thetable shows theM -M (J11 ,J13) andM -T (J12 ,J14) pairs and the number of neighbors with increasing inter-atomic distance.J ~FM! Mn Fe Co Ni J ~AFM! Mn Fe Co NiRh J12(8) 0.041 0.034 0.051 J12(4) 0 0.003 0.001J11(4) 24.550 0.657 0.481 J14(4) 0 0 0J11(2) 0.694 0.792 0.148 J11(4) 23.322 20.157 0.806J11(4) 20.293 0.054 20.043 J13(2) 0.010 20.008 0.002J11(8) 20.400 20.036 0.133 J11(4) 20.587 0.253 20.096J12(8) 0.041 0.034 0.051 J13(8) 0.001 0.004 0.003J11(8) 0.468 20.124 20.155 J14(4) 0 0 0J12(4) 0 0.003 0.014J13(8) 20.246 0.333 0.134Pd J12(8) 0.227 0.234 0.205 0.073 J12(4) 20.093 0.004 0.012 0.030J11(4) 24.331 0.533 1.605 0.241 J14(4) 0 0 0 0J11(2) 1.691 0.090 20.127 20.064 J11(4) 24.951 1.361 1.775 0.172J11(4) 0.042 0.952 0.120 0.038 J13(2) 0 0.010 0.004 0J11(8) 20.223 0.205 0.234 0 J11(4) 0.015 0.401 0.220 0.030J12(8) 0.277 20.234 0.205 0.073 J13(8) 0 0 20.005 0J11(8) 20.230 0.234 20.125 J14(4) 0 0 0 0J12(4) 20.093 0.004 0.012 0.030J13(8) 0.098 0.318 0.174 20.026Ir J12(8) 0.005 0.0156 0.014 J12(4) 0.001 0 0.003J11(4) 21.129 0.748 0.319 J14(4) 0 0 0J11(2) 0.080 0.502 0.095 J11(4) 21.035 0.071 0.404J11(4) 0.204 20.116 20.038 J13(2) 0.003 20.010 0.002J11(8) 20.109 0.067 0.084 J11(4) 0.291 20.065 20.068J12(8) 0.006 0.016 0.014 J13(8) 0.001 20.001 0.001J11(8) 0.097 20.048 20.087 J14(4) 0 0 0J12(4) 0.001 0 0.003J13(8) 20.133 0.235 0.057Pt J12(8) 0.264 0.239 0.226 J12(4) 0.013 0.009 0J11(4) 23.188 0.787 1.305 J14(4) 0 0 0J11(2) 2.650 0.056 20.053 J11(4) 24.847 1.884 1.312J11(4) 20.602 0.711 0.038 J13(2) 20.025 0.017 0.001J11(8) 20.357 0.253 0.267 J11(4) 0.126 20.052 0.113J12(8) 0.263 0.239 0.226 J13(8) 0.004 20.001 20.004J11(8) 20.552 20.400 20.235 J14(4) 0 0 0J12(4) 0.013 0.008 0J13(8) 0.377 0.491 0.3027481J. Appl. Phys., Vol. 95, No. 11, Part 2, 1 June 2004 Kashyap et al.Downloaded 14 Nov 2006 to 129.93.16.206. Redistribution subject to AIP license or copyright, see http://jap.aip.org/jap/copyright.jspabove simple mean-field expression. OurJ0 values are nega-tive for Mn compounds suggesting the AFM order to bemore stable in MnRh, MnPd, MnIr, and MnPt. For the com-pounds of Fe and Co,J0 calculations suggest FM ordering atequilibrium lattice parameters. Compounds of Ni with Rh, Ir,and Pt are paramagnetic~PM! at equilibrium lattice param-eters, in accordance with the experimental data.18 However,the strain dependence of the spin structure may yield transi-tions to a FM state, for example due to embbeding of nano-particles in a matrix. Further experimental complications arecoexistent phases, such as disordered fcc. Table III showssite-resolved exchange interaction parameters@(Ji j )s# for allfor the FM and AFM configurations. Nearest neighborsaround the magnetic 3d transition element~Mn, Fe, Co, Ni!are also given upto a distance of nearly twice the latticeparameter.J11 andJ13 indicate exchange betweenM atomsand J12 and J14 indicate exchange betweenM -T atoms. Asevident from the data in Table III, all Mn compounds exhibitpronounced negative exchange interactions between fourMn-Mn first nearest pairs,J11(4), indicating that the Mnspins in a given plane would prefer to align antiferromagneti-cally, trying to form an intraplane checkerboard pattern inaddition to the AFM interlayer coupling. In all Fe and Cocompounds, FM ordering is more favorable, whereas the Nicompounds are PM, with the exception of the ferromagneticNiPd.IV. CONCLUSIONSWe have performed first-principles calculations forL10compounds of Mn, Fe, Co with Rh, Pd, Pt, Ir. The obtainedmoments and exchange coupling constants are then used todiscuss the spin structure of the intermetallics and to estimatethe ordering temperature. As expected from band-filling ar-guments, there is a trend from ferromagnetism to antiferro-magnetism when going from late 3d elements towards themiddle of the series. However, for some compounds the en-ergy differences are small and strain or doping may stabilizethe FM phase.ACKNOWLEDGMENTSThis research was supported by AFOSR, DOE, NSFMRSEC, by the Keck foundation, and by CMRA. The au-thors would like to acknowledge helpful discussions withProfessor S. S. Jaswal and Professor R. F. Sabirianov. A.K.S.is thankful to MNIT, Jaipur for granting leave.1D. J. Sellmyer, Nature~London! 420, 374 ~2002!.2Cohesion in Metals: Transition Metal Alloys, edited by F. R. de Boer~North-Holland, Amsterdam, 1988!.3H. Zeng, R. F. Sabirianov, O. Mryasov, M. L. Yan, K. Cho, and D. J.Sellmyer, Phys. Rev. B66, 184425~2002!.4T. Klemmer, D. Hoydick, H. Okumura, B. Zhang, and W. A. Soffa, Scr.Metall. Mater.33, 1793~1995!.5Y. Shao, M. L. Yan, and D. J. Sellmyer, J. Appl. Phys.93, 8152~2003!.6R. Skomski, J. Phys.: Condens. Matter15, R841~2003!.7R. Skomski, A. Kashyap, and D. J. Sellmyer, IEEE Trans. Magn.39, 2917~2003!.8G. Brown, B. Kraczek, A. Janotti, T. C. Schulthess, G. M. Stocks, and D.D. Johnson, Phys. Rev. B68, 052405~2003!.9P. Ravindran, A. Kjekshus, H. Fjellvag, P. James, L. Nordstrom, B. Jo-hansson, and O. Eriksson, Phys. Rev. B63, 144409~2001!.10M. T. Johnson, P. J. H. Bloemen, F. J. A. den Broeder, and J. J. de Vries,Rep. Prog. Phys.59, 1409~1996!.11V. L. Moruzzi and P. M. Marcus, Phys. Rev. B48, 16 106~1993!.12D. Garcia, R. Casero, M. Vazquez, and A. Hernando, Phys. Rev. B63,104421~2001!.13A. Sakuma, Phys. Rev. B67, 024420~2003!.14A. Kashyap, A. K. Solanki, T. Nautiyal, and S. Auluck, Phys. Rev. B52,13 471~1995!.15O. K. Andersen, Phys. Rev. B8, 3060~1975!.16P. Villars and L. D. Calvert,Pearsons Handbook of Crystallographic Datafor Intermetallic Phases~American Society of Metals, Metals Park, OH,1985!.17A. I. Liechtenstein, M. I. Katsnelson, V. P. Antropov, and V. A. Gubanov,J. Magn. Magn. Mater.57, 65 ~1988!.18H. P. J. Wijn,Data in Science and Technology~Springer, Berlin, 1991!.7482 J. Appl. Phys., Vol. 95, No. 11, Part 2, 1 June 2004 Kashyap et al.Downloaded 14 Nov 2006 to 129.93.16.206. Redistribution subject to AIP license or copyright, see http://jap.aip.org/jap/copyright.jsp

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Magnetism of \u3ci\u3eL\u3c/i\u3e1\u3csub\u3e0\u3c/sub\u3e compounds with the composition \u3ci\u3eMT\u3c/i\u3e (\u3ci\u3eM\u3c/i\u3e = Rh, Pd, Pt, Ir and \u3ci\u3eT\u3c/i\u3e = Mn, Fe, Co, Ni)

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