Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx
The small nonmonotonic changes of the lattice parameters upon the substitution of Mn for Fe in Ce₂Fe₁₇ lead to significant changes of the magnetic properties. In order to determine the role of the volume, we made ac susceptibility and thermal expansion measurements on the polycrystalline compounds C...
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Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2001
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| Cite this: | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx / O. Prokhnenko , Z. Arnold, J. Kamarad, I. Medvedeva , A. Kuchin // Физика низких температур. — 2001. — Т. 27, № 4. — С. 375-378. — Бібліогр.: 8 назв. — англ. |
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| author | Prokhnenko, O. Arnold, Z. Kamarad, J. Medvedeva, I. Kuchin, A. |
| author_facet | Prokhnenko, O. Arnold, Z. Kamarad, J. Medvedeva, I. Kuchin, A. |
| citation_txt | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx / O. Prokhnenko , Z. Arnold, J. Kamarad, I. Medvedeva , A. Kuchin // Физика низких температур. — 2001. — Т. 27, № 4. — С. 375-378. — Бібліогр.: 8 назв. — англ. |
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| description | The small nonmonotonic changes of the lattice parameters upon the substitution of Mn for Fe in Ce₂Fe₁₇ lead to significant changes of the magnetic properties. In order to determine the role of the volume, we made ac susceptibility and thermal expansion measurements on the polycrystalline compounds Ce₂Fe₁₆.₆₅Mn₀.₃₅ and Ce₂Fe₁₆Mn₁ under hydrostatic pressure up to 10 kbar in the temperature range 10-300 K. The substitution of Mn for Fe leads to significant narrowing of the range of stability of the low-temperature ferromagnetic phase characterized by ΘT =48 K (x=0.35) in comparison with binary Ce₂Fe₁₇, where ΘT =94 K. Applying a relatively small pressure of 1.5 kbar leads to suppression of both the ferromagnetic order and large positive spontaneous volume magnetostriction in Ce₂Fe₁₆.₅Mn₀.₃₅. The pressure effect on ΘT is significant, d ΘT / dp=-30 K/kbar. The effect of pressure on the Néel temperature is moderate and slightly increases with increasing Mn content (dTN / dp= -2.2 K/kbar for Ce₂Fe₁₆.₆₅Mn₀.₃₅). No ferromagnetic order was observed in Ce₂Fe₁₆Mn₁ at ambient pressure, but an unexpected reentering increase of the ac susceptibility was detected at pressures higher than 1.5 kbar below 50 K. It indicates the existence of a pressure-induced ferromagnetic phase at low temperature. The results show not only a strong correlation between the magnetic properties and the lattice volume but also a significant role of the Mn content. 
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Fizika Nizkikh Temperatur, 2001, v. 27, No. 4, p. 375–378Prokh nenko O. , Ar nold Z., Medved evaI., A . Ku chin, an d Ka mar ad J.Mag neto vo lu me an oma lies in Ce2Fe 17– xMnxPro khnen ko O., Ar nold Z. , Med ve devaI., A . Kuchin, a nd Kama rad J. Mag net ovolume a nom alie s in Ce2F e17– xMn x
Magnetovolume anomalies in Ce2Fe17–xMnx
O. Prokhnenko1, Z. Arnold1, I. Medvedeva2, A. Kuchin2, and J. Kamarad1
1 Institute of Physics AS CR, 10 Cukrovarnicka, Prague 6, 16253, Czech Republic
2 Institute of Metal Physics, Ural Division of the Russian Academy of Sciences
18 S. Kovalevskaya, Ekaterinburg 620219, Russia
E-mail: prokhnen@ill.fr
Received October 26, 2000
The small nonmonotonic changes of the lattice parameters upon the substitution of Mn for Fe in
Ce
2
Fe
17
lead to significant changes of the magnetic properties. In order to determine the role of the
volume, we made ac susceptibility and thermal expansion measurements on the polycrystalline com-
pounds Ce2Fe16.65Mn0.35 and Ce2Fe16Mn1 under hydrostatic pressure up to 10 kbar in the temperature
range 10–300 K. The substitution of Mn for Fe leads to significant narrowing of the range of stability
of the low-temperature ferromagnetic phase characterized by Θ
T
= 48 K (x = 0.35) in comparison with
binary Ce2Fe17 , where ΘT = 94 K. Applying a relatively small pressure of 1.5 kbar leads to suppression
of both the ferromagnetic order and large positive spontaneous volume magnetostriction in
Ce2Fe16.5Mn0.35 . The pressure effect on ΘT is significant, dΘT /dp = − 30 K/kbar. The effect of pressure
on the Ne′el temperature is moderate and slightly increases with increasing Mn content
(dTN /dp = − 2.2 K/kbar for Ce2Fe16.65Mn0.35). No ferromagnetic order was observed in Ce2Fe16Mn1 at
ambient pressure, but an unexpected reentering increase of the ac susceptibility was detected at pressures
higher than 1.5 kbar below 50 K. It indicates the existence of a pressure-induced ferromagnetic phase at
low temperature. The results show not only a strong correlation between the magnetic properties and the
lattice volume but also a significant role of the Mn content.
PACS: 75.30.Kz, 75.40.Cx, 65.70.+y
Introduction
Ce2Fe17 crystallizes in a rhombohedral Th2Zn17
type of crystal structure. A number of unusual
features for the set of R2Fe17 compounds (R = rare
earth element) can be singled out. Among them is
an about 4% smaller lattice cell volume of Ce2Fe17
than the regular cell volume of R2Fe17 compounds
extrapolated from its dependence on the rare earth
elements. It has been established that cerium ions
are in an intermediate valence state Ce3+−Ce4+ [1]
in this compound and that they have the smallest
radius among the lanthanides.
Contrary to the majority of the R2Fe17 com-
pounds, the behavior of Ce2Fe17 is peculiar below
the ordering temperature. A susceptibility peak was
observed at TN = 206 K and characterizes a Ne′el
temperature. Below ΘT = 94 K, Ce2Fe17 exhibits
spontaneous magnetization and anomalous thermal
expansion. A noncollinear ferromagnetic arrange-
ment (a fan structure parallel to the basal plane)
and a helimagnetic structure have been determined
by neutron diffraction below ΘT and in the interval
ΘT < T < TN , respectively. These peculiarities
were explained in the model of localized moments
as being the result of a competition of positive and
negative exchange interactions between iron atoms
at different interatomic distances. Due to the small
interatomic Fe–Fe distances in Ce2Fe17 , the con-
tribution of the negative exchange interactions
becomes larger. Consequently, a noncollinear ferro-
magnetic or antiferromagnetic arrangement of the
magnetic moments of the Fe atoms appears [2].
A giant negative pressure effect on ΘT has been
observed: dΘT /dP = − (38 ± 2) K/kbar. The fer-
romagnetic state is suppressed by a critical pressure
of Pc = 2.5 kbar. The pressure effect on the Ne′el
temperature TN = 206 K is significantly smaller:
dTN /dP = − (1.7 ± 0.2) K/kbar [3]. The large
positive spontaneous volume magnetostriction ob-
served below TN is suppressed by application of
high pressure and disappears at P > Pc . The pres-
sure effect on the magnetic ordering was confirmed
by neutron diffraction experiments [4].
The substitution of Mn for Fe leads to small
changes of the lattice parameters but to significant
© O. Prokhnenko, Z. Arnold, I. Medvedeva, A. Kuchin, and J. Kamarad, 2001
changes of the magnetic properties of the Ce2Fe17
compound. The ferromagnetic phase disappears in
Ce2Fe17−xMnx compounds for x ≥ 0.5, but a new,
probably noncollinear ferromagnetic phase appears
again for x > 1 [5]. To characterize the role of the
volume in more detail, we performed high-hydro-
static-pressure studies (up to 10 kbar) of the ac
susceptibility and thermal expansion of polycrystal-
line Ce2Fe16.65Mn0.35 and Ce2Fe16Mn1 compounds
in the temperature range 10–300 K.
Experimental
The polycrystalline samples of Ce2Fe16.65Mn0.35
and Ce2Fe16Mn1 were prepared by the induc-
tion melting method with subsequent annealing at
1000 °C for two weeks. The samples were tested
by x-ray diffraction. The lattice parameters
a = 8.493 A° , c = 12.411 A° and a = 8.505 A° , c =
= 12.428 A° of Ce2Fe16.65Mn0.35 and Ce2Fe16Mn1 ,
respectively, were determined [6]. The ac-suscepti-
bility and thermal expansion measurements were
carried out in the temperature range 12–300 K in a
Closed Cycle Refrigerator Cryostat (Cryophysics
Ltd.) under hydrostatic pressure up to 10 kbar
using a standard Cu–Be piston-cylinder cell. Mea-
surements of the ac susceptibility were performed
by the transformer method. The thermal expansion
was measured by micro-strain gauges (Micro-Mea-
surements Inc., SK-350).
Results
The temperature dependences of the ac suscepti-
bility χ and thermal expansion ∆L/L of the
Ce2Fe16.65Mn0.35 compound at different pressures
are visualized in Fig. 1.
At ambient pressure (Figs. 1,a, 2,a — 0 kbar
curves) the drop of the susceptibility and thermal
expansion around 50 K corresponds to a magnetic
transition from the ferromagnetic to antiferromag-
netic state (similar behavior of both the ac suscep-
tibility and thermal expansion were observed in
binary Ce2Fe17 around 95 K). Both the small sus-
ceptibility peak and the change of the character of
the temperature dependence ∆L/L around 200 K
correspond to a magnetic transition from an antifer-
romagnetic to a paramagnetic state. The transition
temperature ΘT = 48 K was determined as an inflec-
tion point of the χ(T) curve and the Ne′el tempera-
ture TN = 211 K was defined as the maximum of
χ(T). The thermal expansion behavior is rather
complex. Anomalous positive spontaneous magne-
tostriction was observed below 100 K. The thermal
expansion coefficient is negative below TN . It
equals zero at TN and becomes positive at high
temperatures.
Applying pressure leads to a steep decrease of the
magnetic susceptibility and transition temperature
ΘT , dΘT /dP = − 30 K/kbar. At a critical pres-
sure Pc > 1.5 kbar the ferromagnetic phase disap-
pears. The shift of Ne′el temperature TN with pres-
sure (see the inset in Fig. 1,a) is significantly
smaller, dTN /dP = − 2.2 K/kbar, compared to
the ΘT decrease. The thermal expansion anomalies
in the vicinity of ΘT and TN (Fig. 1,b) are strongly
suppressed by pressure and practically disappear at
pressures P > 1.5 kbar and P > 4 kbar, respec-
tively.
We did not observe any presence of low tempera-
tures anomalies (e.g., a ferromagnetic phase) in the
temperature dependence of the ac susceptibility of
Ce2Fe16Mn1 at ambient conditions (Fig. 2,a,
0 kbar curve).
A pronounced susceptibility peak was observed
around 200 K. It should correspond to the transi-
Fig. 1. Temperature dependence of the ac susceptibility (a) and
thermal expansion (b) of Ce2Fe16.65Mn0.35 under pressure.
b
a
O. Prokhnenko et al.
376 Fizika Nizkikh Temperatur, 2001, v. 27, No. 4
tion from an antiferromagnetic to a paramagnetic
state. The temperature of this transition
TN = 196 K was defined as the maximum of the
χ(T) curve. Positive spontaneous magnetostriction
was observed below TN as an appreciable change of
the character of ∆L/L dependence (Fig. 2,b, 0 kbar
curve). However, the thermal expansion coefficient
is positive in the whole temperature range.
Applying pressure, as in previous cases, results in
a decrease of the ac susceptibility (inset in Fig. 2,a)
and Ne′el temperature, dTN /dP = − 2.3 K/kbar.
The thermal expansion anomaly below TN
(Fig. 2,b) decreases under pressure and practically
disappears at P > 1.2 kbar. However, at pressures
P ≥ 1.5 kbar an unexpected increase of the suscepti-
bility was observed at temperatures below 50 K
(Fig. 2,a). This increase is not accompanied by any
anomalies in the thermal expansion.
Using all available data (Table) the magnetic
phase P−T diagrams of Ce2Fe16.65Mn0.35 and
Ce2Fe16Mn1 compounds were created (Fig. 3).
Table
Transition temperatures and their pressure derivatives of
Ce
2
Fe
17−x
Mn
x
compounds
Ce
2
Fe
17−x
Mn
x
Θ
T
,
K
dΘ
T
/dP,
K/kbar
P
c
,
kbar
T
N
,
K
dT
N
/dP,
K/kbar
x = 0 94 –38 2.5 206 –1.7
x = 0.35 48 –30 1.5 211 –2.2
x = 1 — — — 196 –2.3
Fig. 2. Temperature dependence of ac susceptibility (a) and
thermal expansion (b) of Ce2Fe16Mn1 under pressure.
Fig. 3. P−T magnetic phase diagrams of the compounds
Ce2Fe16.65Mn0.35 (a) and Ce2Fe16Mn1 (b) (FM — ferromagne-
tic phase, AFM — antiferromagnetic phase, PM — paramag-
netic phase).
a
b
b
a
Magnetovolume anomalies in Ce2Fe17–x
Mn
x
Fizika Nizkikh Temperatur, 2001, v. 27, No. 4 377
Conclusion
According to [7,8], the changes of the lattice
parameter c due to the substitution of nonmagnetic
elements (e.g., Al, Ga) for Fe seem to have a large
influence on the magnetic properties of Ce2Fe17. In
our case the substitution of Mn for Fe in Ce2Fe17
leads not only to nonmonotonic changes of the
lattice parameters but also to the appearance of
Mn–Mn and Fe–Mn exchange interactions at dif-
ferent sites. As a result, a decrease of the transition
temperature ΘT in Ce2Fe17−xMnx with the sub-
sequent disappearance of the ferromagnetic state for
0.5 ≤ x ≤ 1 and its reappearance for x > 1 was ob-
served [5,6].
The appearance of the new, probably noncolli-
near ferromagnetic phase at low temperatures at
pressures P ≥ 1.5 kbar in Ce2Fe16Mn1 compound
was a rather unexpected result. Pressure usually
destabilizes the ferromagnetic order, but in our case
it leads to an increase of the transition temperature
with increase of pressure. This behavior can hardly
be explained using competition between positive
and negative exchange interactions, as both the
Fe–Fe and the Mn–Mn exchange interactions ex-
hibit the same character of the distance dependence.
As the Ce2Fe16Fe1 has the largest c lattice pa-
rameter among the set of Ce2Fe17−xMnx compounds
with x < 2.5 [6], one can suggest that the new
pressure-induced phase in Ce2Fe16Mn1 could be the
same phase as the above-mentioned low-temperature
phase in Ce2Fe17−xMnx for x > 1. Its creation can
be caused by the decrease of the c lattice parameter
under pressure.
We can conclude that the observed complex
magnetic behavior of the Ce2Fe17−xMnx compounds
under high pressures is the consequence of both the
decrease of the lattice volume and the role of the
Mn content.
We acknowledge the support from Projects
No. 106/99/0183 GA CR, A1010018 GA AS CR
and from the Russian Foundation for Basic Re-
search, Project No. 98-02-16165.
1. J. M. D. Coey, J. E. M. Allan, A. A. Minakov, and Yu. V.
Bugaslavsky, J. Appl. Phys. 73, 5430 (1993).
2. D. Givord and R. Lemaire, IEEE Trans. Magn. MAG-10,
109 (1974).
3. I. Medvedeva, Z. Arnold, A. Kuchin, and J. Kamarad, J.
Appl. Phys. 86, 6295 (1999).
4. Z. Arnold, O. Prokhnenko, and A. E. Teplykh, unpublished
results.
5. A. G. Kuchin et al., Proceedings of MISM’99, Moscow,
June 1999, part 2, p. 339.
6. A. G. Kuchin, A. N. Pirogov, V. I. Khrabrov, A. E.
Teplykh, A. S. Ermolenko, and E. V. Belozerov, Proceed-
ings of EMMA2000, in print.
7. S. R. Mishra, Gary L. Long, O. A. Pringle, D. P. Middle-
ton, Z. Hu, W. Yelon, F. Grandjean, and K. H. J.
Buschow, J. Appl. Phys. 79, 3145 (1996).
8. D. P. Middleton, S. R. Mishra, Gary L. Long, O. A.
Pringle, Z. Hu, W. Yelon, F. Grandjean, and K. H. J.
Buschow, J. Appl. Phys. 78, 5568 (1995).
O. Prokhnenko et al.
378 Fizika Nizkikh Temperatur, 2001, v. 27, No. 4
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| id | nasplib_isofts_kiev_ua-123456789-130013 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0132-6414 |
| language | English |
| last_indexed | 2025-12-07T18:03:44Z |
| publishDate | 2001 |
| publisher | Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| record_format | dspace |
| spelling | Prokhnenko, O. Arnold, Z. Kamarad, J. Medvedeva, I. Kuchin, A. 2018-02-04T16:11:05Z 2018-02-04T16:11:05Z 2001 Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx / O. Prokhnenko , Z. Arnold, J. Kamarad, I. Medvedeva , A. Kuchin // Физика низких температур. — 2001. — Т. 27, № 4. — С. 375-378. — Бібліогр.: 8 назв. — англ. 0132-6414 PACS: 75.30.Kz, 75.40.Cx, 65.70.+y https://nasplib.isofts.kiev.ua/handle/123456789/130013 The small nonmonotonic changes of the lattice parameters upon the substitution of Mn for Fe in Ce₂Fe₁₇ lead to significant changes of the magnetic properties. In order to determine the role of the volume, we made ac susceptibility and thermal expansion measurements on the polycrystalline compounds Ce₂Fe₁₆.₆₅Mn₀.₃₅ and Ce₂Fe₁₆Mn₁ under hydrostatic pressure up to 10 kbar in the temperature range 10-300 K. The substitution of Mn for Fe leads to significant narrowing of the range of stability of the low-temperature ferromagnetic phase characterized by ΘT =48 K (x=0.35) in comparison with binary Ce₂Fe₁₇, where ΘT =94 K. Applying a relatively small pressure of 1.5 kbar leads to suppression of both the ferromagnetic order and large positive spontaneous volume magnetostriction in Ce₂Fe₁₆.₅Mn₀.₃₅. The pressure effect on ΘT is significant, d ΘT / dp=-30 K/kbar. The effect of pressure on the Néel temperature is moderate and slightly increases with increasing Mn content (dTN / dp= -2.2 K/kbar for Ce₂Fe₁₆.₆₅Mn₀.₃₅). No ferromagnetic order was observed in Ce₂Fe₁₆Mn₁ at ambient pressure, but an unexpected reentering increase of the ac susceptibility was detected at pressures higher than 1.5 kbar below 50 K. It indicates the existence of a pressure-induced ferromagnetic phase at low temperature. The results show not only a strong correlation between the magnetic properties and the lattice volume but also a significant role of the Mn content. 
 Remove selected We acknowledge the support from Projects
 No. 106/99/0183 GA CR, A1010018 GA AS CR
 and from the Russian Foundation for Basic Research,
 Project No. 98-02-16165. en Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України Физика низких температур Низкотемпеpатуpная магнитостpикция магнетиков и свеpхпpоводников Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx Article published earlier |
| spellingShingle | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx Prokhnenko, O. Arnold, Z. Kamarad, J. Medvedeva, I. Kuchin, A. Низкотемпеpатуpная магнитостpикция магнетиков и свеpхпpоводников |
| title | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx |
| title_full | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx |
| title_fullStr | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx |
| title_full_unstemmed | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx |
| title_short | Magnetovolume anomalies in Ce₂Fe₁₇₋xMnx |
| title_sort | magnetovolume anomalies in ce₂fe₁₇₋xmnx |
| topic | Низкотемпеpатуpная магнитостpикция магнетиков и свеpхпpоводников |
| topic_facet | Низкотемпеpатуpная магнитостpикция магнетиков и свеpхпpоводников |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/130013 |
| work_keys_str_mv | AT prokhnenkoo magnetovolumeanomaliesince2fe17xmnx AT arnoldz magnetovolumeanomaliesince2fe17xmnx AT kamaradj magnetovolumeanomaliesince2fe17xmnx AT medvedevai magnetovolumeanomaliesince2fe17xmnx AT kuchina magnetovolumeanomaliesince2fe17xmnx |