MÖSSBAUER SPECTROSCOPY OF DyMe2Si2 COMPOUNDS

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MÖSSBAUER SPECTROSCOPY OF DyMe2Si2 COMPOUNDS

E. Görlich, A. Hrynkiewicz, K. Lątka, R. Kmieć, A. Szytula, K. Tomala

To cite this version:

E. Görlich, A. Hrynkiewicz, K. Lątka, R. Kmieć, A. Szytula, et al.. MÖSSBAUER SPECTROSCOPY OF DyMe2Si2 COMPOUNDS. Journal de Physique Colloques, 1979, 40 (C2), pp.C2-656-C2-657.

�10.1051/jphyscol:19792228�. �jpa-00218609�

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JOURNAL DE PHYSIQUE

Colloque C2, supplkment au n

3,

Tome 40, mars 1979, page C2-656

MOSSBAUER S P E C T R O S C O P Y

OF

D y M e S i C O M P O U N D S 2 2

E.A. ~ ~ r l i c h * , A.Z. Hrynkiewicz *%

,

K. L5tka

*,

R. ICmiecM*, A. ~ z y t u ~ a * , and K. ~omala*

* ~ n s t i t u t e o f Physics, JageZZaian Unioersity, Cracow, Poland

*x I n s t i t u t e o f Nuclear Physics, Cracow, Poland

Rdsum6.- On prdsente les rdsultats d'absorption rdsonante de ' 6 1 ~ y dans les composds DyMenSin (Me = Mn, Fe, Co, Ni et Cu) et de 5 7 ~ e dans DyFe~Si2.

Abstract.- Results of resonance absorption measurements on 16'Dy nuclei in DyMe2Si2 compounds (Me = Mn, Fe, Co, Ni and Cu) and on 5 7 ~ e nuclei in DyFezSiz are presented.

Compounds represented by the formula ReMezCiz, cent for the quadrupole interaction.

where Re is the rare earth and Me the 3d metal,

crystallize in the ThCrzSiz type tetragonal structu- Table I : Hyperfine parameters obtained from ' 6 1 ~ y re in the space group I 4 / m /I/. Investigated com- resonance absorption measurements in

DyMe2Si2 compounds.

pounds were prepared by arc-melting of dysprosium, silicon and the 3d metal (Mn, Fe, Co Ni or Cu) in argon atmosphere. To achieve good homogeneity they were annealed in vacuum at 800'~ for ca. 4 days. The X-ray analysis indicated in each case the presence of a single phase. All absorbers were prepared in a powder form with the natural abundance of the

'

^{6 1 ~ y}

isotope.

The Mgssbauer effect measurements for ' 6 1 ~ y nuclei were carried out with the 16'~d203 source at room temperature using a 2 atm.Kr proportional coun- ter for detection of the 25.6 keV gamma line. The velocity scale of the spectrometer was calibrated with a Dy-metal absorber.

Bulk magnetization measurements, performed until low, show that DyFezSiz and DyNiZSiz are para- magnets down to 4.2 K whereas DyCo2Siz is antiferro- magnetically ordered below 19 K.

All ' 6 1 ~ y resonance absorption spectra taken at liquid helium temperature reveal the hyperfine splitting caused in paramagnetic samples by the long relaxation time of the dysprosium magnetic moment.

For DyMr1~Si.2 and DyNizSi2 the hfs spectra at 4.2 K could not be described in terms of the static magnetic interaction. Therefore, measurements for these compounds were also done at temperatures below 4.2 K.

spectra. obtained for DyMn2Si2 at 1.85 K and for DyNipSi2 at 2.1 K can be satisfactorily fitted using the static hyperfine Hamiltonian. In figure 1 the Dy spectrum for DyFezSiz is shown as an example. In table I the obtained ratios I$f/(Hhf)Dy-metal and eq'(eq)~y-metal are presented. In all cases errors amount to 0.2 per cent for the magnetic and to 4 per

t I 1 I

Lattice

: j

^eqi ~ T ~ ~ ~ ( K ) Compound

:

^constants

:

1 (\f)Dy: (eq)Dy

: j

^a(K)

~(1) ;

¹ ^t

I I I 1 I

I I 1 1 I

DyMn2Si2

:

^3.93

:

^10.24

:

^0.999

:

^0.93

:

^1.85

1 I I I I

DyFe2Si2

_, :

^3.90

:

^9.97

:

^0.998

:

^0.87

:

^4.5

I I 1 I

DyCo2Siz

:

^3.89

:

^9.75

:

^0.970

:

^0.89

:

^7.0

t

,

DyNizSiz

:

^3.95

:

^9.55

:

^0.911

:

^0.80

:

^2.1

r I

,

¹ ^I

DyCuzSi2

:

^3.98

:

^10.10

:

^0.887

:

^0.77

:

^6.4

I P 1 1 f

The hyperfine magnetic fields and the electric field gradients change considerably along the series of the investigated compounds. Because of a quite small change of lattice constants the variation of the hyperfine fields can be probably attributed to the change of the polarization density of the con- duction electrons.

The iron resonance absorption in DyFe2Si2 does not reveal any magnetic splitting of the Fe ~ 6 ~ s - bauer spectrum down to the temperature of 2 K. This contradicts the results obtained by Felner et al.

121, where the superposition of single and magnetically splitted components was observed for Fe in the same kind of compounds. The value of the isomer shift for 5 7 ~ e nuclei (+0.19

*

0.04 mm/s) with res- pect to Fe metal excludes, in our opinion, the possi- bility of 3dI0 configuration for iron ions, suggested in /3/. The configuration of the low spin Fez+ seems to be more justified.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19792228

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I I I I I

-30 0 -15.0 00 150 300

VELOCITY tcmlsl

Fig. 1 :

'

^{6 1 ~ y}resonance absorption spectrum for DyFezSin

Fig. 2 : 5 7 ~ e resonance absorption spectrum for DyFe2Si2

References

/I/ Sikirica, M. and Ban, Z., Acta Cryst.

2

(1965) 594.

121 Felner, I., Mayer, I., Grill, A . , and Schieber, M., Solid State C o m u n 16(1975) 1005.

131 Felner, I., J. Phys. Chem. Solids

36

(1975) 1063.