Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ
The crystal structure and magnetic properties of the La₁₋xBixMnO₃₊λ system (0⩽x⩽1;λ⩽0.08) are studied as functions of the oxygen and bismuth contents. In oxidized samples La₁₋xBixMnO₃₊λ a phase transition from a ferromagnetic state (rhombohedric phase) to a state of the spin glass type (quasitetrago...
Gespeichert in:
| Datum: | 2002 |
|---|---|
| Hauptverfasser: | , , , |
| Format: | Artikel |
| Sprache: | English |
| Veröffentlicht: |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2002
|
| Schriftenreihe: | Физика низких температур |
| Schlagworte: | |
| Online Zugang: | https://nasplib.isofts.kiev.ua/handle/123456789/130236 |
| Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Zitieren: | Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ / I.O. Troyanchuk, O.S. Mantytskaja, H.Szymczak, M.Yu. Shvedun // Физика низких температур. — 2002. — Т. 28, № 7. — С. 790-795. — Бібліогр.: 28 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-130236 |
|---|---|
| record_format |
dspace |
| spelling |
nasplib_isofts_kiev_ua-123456789-1302362025-02-09T14:07:37Z Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ Troyanchuk, I.O. Mantytskaja, O.S. Szymczak, H. Shvedun, M.Yu. Дефекты в кристаллах The crystal structure and magnetic properties of the La₁₋xBixMnO₃₊λ system (0⩽x⩽1;λ⩽0.08) are studied as functions of the oxygen and bismuth contents. In oxidized samples La₁₋xBixMnO₃₊λ a phase transition from a ferromagnetic state (rhombohedric phase) to a state of the spin glass type (quasitetragonal phase) is observed with increase of the bismuth concentration. The reduced samples La₁₋xBixMnO₃ are weak ferromagnets down to x⩽0.6 and then transform into a ferromagnetic state. It is supposed that the Bi³⁺ ions stabilize the dx2−y2 orbitals in the nearest Mn³⁺ ions whereas the dz2 orbitals of the La³⁺ ions are stabilized. The orbitally disordered phases and dx2−y2-orbitally ordered phases are ferromagnetic, the dz2-orbitally ordered phases show antiferromagnetic ordering, and the state of the orbital glass type corresponds to a state of the spin glass type. The crystal structure and magnetic properties of the La₁₋xBixMnO₃₊λ system (0⩽x⩽1;λ⩽0.08) are studied as functions of the oxygen and bismuth contents. In oxidized samples La₁₋xBixMnO₃₊λ a phase transition from a ferromagnetic state (rhombohedric phase) to a state of the spin glass type (quasitetragonal phase) is observed with increase of the bismuth concentration. The reduced samples La₁₋xBixMnO₃ are weak ferromagnets down to x⩽0.6 and then transform into a ferromagnetic state. It is supposed that the Bi³⁺ ions stabilize the dx2−y2 orbitals in the nearest Mn³⁺ ions whereas the dz2 orbitals of the La³⁺ ions are stabilized. The orbitally disordered phases and dx2−y2-orbitally ordered phases are ferromagnetic, the dz2-orbitally ordered phases show antiferromagnetic ordering, and the state of the orbital glass type corresponds to a state of the spin glass type. This work was supported in part by the Belarus Fund of Basic Research (Project F00-223). 2002 Article Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ / I.O. Troyanchuk, O.S. Mantytskaja, H.Szymczak, M.Yu. Shvedun // Физика низких температур. — 2002. — Т. 28, № 7. — С. 790-795. — Бібліогр.: 28 назв. — англ. 0132-6414 PACS: 72.15.Gd, 75.30.Kz, 75.70.Pa https://nasplib.isofts.kiev.ua/handle/123456789/130236 en Физика низких температур application/pdf Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| topic |
Дефекты в кристаллах Дефекты в кристаллах |
| spellingShingle |
Дефекты в кристаллах Дефекты в кристаллах Troyanchuk, I.O. Mantytskaja, O.S. Szymczak, H. Shvedun, M.Yu. Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ Физика низких температур |
| description |
The crystal structure and magnetic properties of the La₁₋xBixMnO₃₊λ system (0⩽x⩽1;λ⩽0.08) are studied as functions of the oxygen and bismuth contents. In oxidized samples La₁₋xBixMnO₃₊λ a phase transition from a ferromagnetic state (rhombohedric phase) to a state of the spin glass type (quasitetragonal phase) is observed with increase of the bismuth concentration. The reduced samples La₁₋xBixMnO₃ are weak ferromagnets down to x⩽0.6 and then transform into a ferromagnetic state. It is supposed that the Bi³⁺ ions stabilize the dx2−y2 orbitals in the nearest Mn³⁺ ions whereas the dz2 orbitals of the La³⁺ ions are stabilized. The orbitally disordered phases and dx2−y2-orbitally ordered phases are ferromagnetic, the dz2-orbitally ordered phases show antiferromagnetic ordering, and the state of the orbital glass type corresponds to a state of the spin glass type. |
| format |
Article |
| author |
Troyanchuk, I.O. Mantytskaja, O.S. Szymczak, H. Shvedun, M.Yu. |
| author_facet |
Troyanchuk, I.O. Mantytskaja, O.S. Szymczak, H. Shvedun, M.Yu. |
| author_sort |
Troyanchuk, I.O. |
| title |
Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ |
| title_short |
Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ |
| title_full |
Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ |
| title_fullStr |
Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ |
| title_full_unstemmed |
Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ |
| title_sort |
magnetic phase transitions in the system la₁₋xbixmno₃₊λ |
| publisher |
Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| publishDate |
2002 |
| topic_facet |
Дефекты в кристаллах |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/130236 |
| citation_txt |
Magnetic phase transitions in the system La₁₋xBixMnO₃₊λ / I.O. Troyanchuk, O.S. Mantytskaja, H.Szymczak, M.Yu. Shvedun // Физика низких температур. — 2002. — Т. 28, № 7. — С. 790-795. — Бібліогр.: 28 назв. — англ. |
| series |
Физика низких температур |
| work_keys_str_mv |
AT troyanchukio magneticphasetransitionsinthesystemla1xbixmno3l AT mantytskajaos magneticphasetransitionsinthesystemla1xbixmno3l AT szymczakh magneticphasetransitionsinthesystemla1xbixmno3l AT shvedunmyu magneticphasetransitionsinthesystemla1xbixmno3l |
| first_indexed |
2025-11-26T15:23:23Z |
| last_indexed |
2025-11-26T15:23:23Z |
| _version_ |
1849866959571648512 |
| fulltext |
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7, p. 790–795
Magnetic phase transitions in the system
La1–xBixMnO3+�
I. O. Troyanchuk and O. S. Mantytskaja
Institute of Solid State and Semiconductor Physics of National Academy of Sciences of Belarus
17 P. Brovki Str., Minsk 220072, Belarus
E-mail: troyan@ifttp.bas-net.by
H. Szymczak
Institute of Physics of Polish Academy of Sciences
32/46 Al. Lotnikow Str., Warsaw PL-02-668, Poland
M. Yu. Shvedun
B. Verkin Institute for Low Temperature Physics and Engineering
of the National Academy of Science of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine
Received January 4, 2002
The crystal structure and magnetic properties of the La1-xBixMnO3+� system ( ;0 1� �x
� � 008. ) are studied as functions of the oxygen and bismuth contents. In oxidized samples
La1–xBixMnO3+� a phase transition from a ferromagnetic state (rhombohedric phase) to a
state of the spin glass type (quasitetragonal phase) is observed with increase of the bismuth
concentration. The reduced samples La1–xBixMnO3 are weak ferromagnets down to x � 06. and
then transform into a ferromagnetic state. It is supposed that the Bi3 + ions stabilize the
dx y2 2�
orbitals in the nearest Mn3+ ions whereas the dz2 orbitals of the La3+ ions are stabi-
lized. The orbitally disordered phases and dx y2 2�
— orbitally ordered phases are ferromag-
netic, the dz2 — orbitally ordered phases show antiferromagnetic ordering, and the state of
the orbital glass type corresponds to a state of the spin glass type.
PACS: 72.15.Gd, 75.30.Kz, 75.70.Pa
Introduction
Recently considerable interest has been attracted
to strongly correlated systems with perovskite-like
structure. The variety of triple perovskites such as
RMO3 (R is a rare-earth metal, M is a transition
metal) is quite great, but with variation of the
rare-earth element (R = La, Pr, Nd etc.) and the
addition of the practically unlimited set of solu-
tions R1–xAxMnO3, the number of combinations
becomes extremely large.
Manganites R1–xAxMnO3 have interesting and
unusual properties. These compounds contain ions
with orbital degeneracy or Jahn–Teller (JT) ions
(in our case Mn3+) [1]. Thus their properties differ
appreciably from those of the corresponding sub-
stances with the «ordinary» ions: the crystal
structure turn out to be distorted, structural phase
transitions and transitions in a magnetic subsystem
[2–6] are frequently observed in them, and in many
cases they have anomalously strong magnetic aniso-
tropy and magnetostriction [7,8]. Such phenomena
are connected with an interaction of the JT ions
and are called the cooperative Jahn–Teller effect
(CJTE). Distortions of the crystal lattice are
caused by the fact that ion Mn3+ is degenerate with
respect to the d orbitals: the crystal field splits the
atomic d level into two- and threefold degenerate
sublevels eg and t2g (the eg state is characterized by
the real wave functions dz2 and dx y2 2�
). The first
of them lies above the second one, and conse-
quently the four d electrons of the Mn3+ ion occupy
© I. O. Troyanchuk, O. S. Mantytskaja, H. Szymczak, and M. Yu. Shvedun, 2002
the level t2g completely and the level eg only in
part. This also makes CJTE possible, which reduces
the energy of such a degenerate system by lowering
its symmetry, which lifts the degeneracy of the
electronic levels.
Despite the numerous works devoted to research
on manganites, many problems remain subject to
discussion. The unusual magnetic behavior of bis-
muth-containing manganites is one such problem.
While the lanthanum-based manganites (Ln–La, Y,
rare-earth ion) are antiferromagnetic [9], bismuth
manganite is a ferromagnetic insulator [10,11]. Mo-
reover, while substitution of the lanthanoid by an
alkaline-earth metal leads to a transition from the
antiferromagnetic to a ferromagnetic metallic state
[12], a similar substitution for BiMnO3-based man-
ganites destroys the ferromagnetic order [13–15].
The aim of the present work is to study phase
transitions in a system of manganites where La3+
ions are replaced by Bi3+ ions. Formally upon such
a substitution the valence of the manganese ions
should not change.
Experiment
Samples of the La1-xBixMnO
3+�
system were
obtained by three different methods: in air, under a
high pressure, and in vacuum. The initial reagents
were oxides of La2O3, Bi2O3 and Mn2O3, mixed in
the desired proportion. The manganite of lantha-
num was obtained at Ò = 1500 °C in air. Synthesis
of Bi-containing samples was carried out in the
temperature range of 900–1150 °C with a subse-
quent slow cooling (100 °C/h). The temperature of
synthesis decreased with increasing bismuth con-
tent from 1150 °C (x � 0.2) to 900 °Ñ (x � 0.7). Ac-
cording to x-ray phase analysis, in a sample with
x � 0.7 there were traces of extraneous phases;
therefore in these states the saturated concentration
of bismuth is limited to a value of 65%. A chemical
analysis has shown that all compounds obtai-
ned in air have an excess of oxygen in comparison
with the stoichiometric ratio. Substitution of the
La3+ ions by Bi3+ has only a weak influence on
the oxygen content. The chemical formula is
La1-xBixMnO3.07±0,01. The samples prepared by the
method described were reduced in quartz vacuum
tubes at 900 °Ñ in the presence of tantalum metal
for absorption of allocated oxygen. Control of the
oxygen maintenance was carried out by mass
weighing of the sample before and after the reduc-
tion process. The chemical formula was «squared
up» on loss of the mass. Compounds with x � 0.7
were obtained using a high-pressure technique
(pressure 4 GPa, temperature 900 °Ñ, duration of
synthesis 20 min). These samples were characterized
by the chemical composition La1-xBixMnO3±0,01.
X-ray structure studies were carried out on
a DRON-3 diffractometer in Cr K
�
radiation. Sing-
le-phase structures were selected for measurement
of the magnetic and electric properties. Magnetic
measurements were carried out on a commercial vi-
brating Foner magnetometer. The electroconduc-
tivity was measured by a standard four-probe techni-
que. Indium contacts were used. They were applied
using ultrasound.
Results and discussion
According to the x-ray data, the samples of the
La1–xBixMnO3.07 series obtained in air were cha-
racterized by rhombohedral distortions of the unit
cell up to a concentration x � 0.4. In samples with
x � 0.5 the type of distortions changed to tetra-
gonal. The compounds reduced in vacuum and ob-
tained under a high pressure had a monoclinic or
orthorhombic deformed unit cell.
Upon substitution of lanthanum by bismuth, the
volume of the unit cell varied only slightly, appa-
rently because of the similarity of the ionic radii of
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 791
Magnetic phase transitions in the system La1–x
Bi
x
MnO3+�
Table 1
Unit cell parameters of La1–xBixMnO3,07 compounds obtained in air
Composition Symmetry a, Å c, Å �, deg V, Å3
LaMnO
3.07
R 7.8105 — 90.46 59.55
La
0.8
Bi
0.2
MnO
3.07
R 7.8165 — 90.45 59.69
La
0.7
Bi
0.3
MnO
3.07
R 7.8191 — 90.34 59.75
La
0.6
Bi
0.4
MnO
3.07
R 7.8198 — 90.27 59.7
La
0.5
Bi
0.5
MnO
3.07
T 3.9098 3.9352 — 60.156
La
0.4
Bi
0.6
MnO
3.07
T 3.9048 3.9409 — 60.09
La3+ and Bi3+. The unit cell parameters of some
solid solutions are given in Tables 1 and 2. Accor-
ding to structural studies [16], the excess over stoi-
chiometric oxygen in the system LaMnO3+�
is a
consequence of the formation of an equivalent num-
ber of vacancies of La3+ and Mn3+ ions. Apparently
this mechanism of nonstoichiometry is pertinent to
system La1-xBixMnO
3+�
also, as the oxygen ions
cannot occupy interstitial positions in the close-
packed perovskite structure.
Field curves of the magnetization M(H) at liquid
helium temperature for several samples prepared in
air are shown in Fig. 1. LaMnO3,07 is ferromag-
netic, as the specific magnetization corresponds to a
parallel orientation of the magnetic moments of the
manganese ions. With increase of the bismuth con-
tent up to x � 0.65, a gradual decrease of the spon-
taneous magnetization was observed. In compounds
with x � 0.6 and x � 0.65 the magnetization remains
unsaturated in fields up to 16 kOe, as is typical for
792 Fizika Nizkikh Temperatur, 2002, v. 28, No. 7
I. O. Troyanchuk, O. S. Mantytskaja, H. Szymczak, and M. Yu. Shvedun
Fig. 2. Temperature dependence of the magnetization in
the La1-xBixMnO3.07 system (ZFC curve — filled sym-
bols, FC — unfilled symbols).
Fig. 3. Magnetic field dependence of the magnetization
in the La0.5Bi0.5MnO3+� system.
Fig. 4. Temperature dependence of the magnetization in
the La0.5Bi0.5MnO3+� system (ZFC curve — filled sym-
bols, FC — unfilled symbols).
Fig. 1. Magnetic field dependence of the magnetization
in the La1-xBixMnO3.07 system.
Table 2
Unit cell parameters of La1–xBixMnO3+�
compounds obtained in vacuum
Composition Symmetry a, Å b, Å c, Å V, Å3
La
0.5
Bi
0.5
MnO
3.07
Ò 3.9098 3.9352 — 60.15
La
0.5
Bi
0.5
MnO
3.04
Î 5.5456 5.5879 7.7862 61.095
La
0.5
Bi
0.5
MnO
2.99
�O 5.501 5.8266 7.6635 61.41
magnets with weak cooperative exchange interac-
tions. Ferromagnetic solutions (x � 0 4. ) are soft
magnetic materials whereas in samples with x � 0 5.
the coercive force sharply increases. The tempera-
ture curves of the magnetization obtained in a
rather small external magnetic field of 100 Oe are
shown in Fig. 2. The measurements were performed
in a mode of heating after cooling in a field (FC)
and without a field (ZFC). It follows from the dia-
grams that the Curie temperature decreases with in-
crease of bismuth content. The ZFC magnetization
of a sample with x � 0.6 has a wide maximum,
which is typical for a magnet near the concentra-
tion transition from a ferromagnetic state to the
state such as a spin glass. On further increase of the
bismuth content the magnetic susceptibility sharply
decreases. The ZFC magnetization in a sample with
x � 0.65 has a well-defined maximum. Near the
temperature of the maximum the ZFC and FC
magnetizations diverge. Taking into account the
form of M(Í) curve we believe that in solutions
with x � 0.65 the long-range magnetic order is ap-
parently destroyed.
The compound La0.5Bi0.5MnO3.07 was reduced
under various conditions. As a result, two com-
pounds — La0.5Bi0.5MnO3.04 and La0.5Bi0.5MnO2.99
are obtained. The partially reduced sample had an
O-orthorhombically distorted unit cell (a c b� �2 ),
whereas the strongly reduced had O�-orthorhom-
bically deformed unit cell (c a b2 � � ). It should
be noted, that O�-orthorhombic distortions in man-
ganites indicate orbital ordering [17]. The field
curves of the magnetization at liquid helium tem-
perature for reduced samples are plotted in Fig. 3.
The magnetizations of compounds with � = 0.04
and � = 0.07 differ slightly, whereas the composi-
tion with � = – 0.01 has a very small spontaneous
magnetization (about 0.2 B in formula units).
With loss of oxygen the critical temperature at
which a spontaneous magnetization appears at first
decreased and then increased again and, moreover,
the transition to the paramagnetic state became
sharper (Fig. 4).
It should be noted that with decrease of the oxy-
gen content in the reduced manganites the mag-
netic anisotropy increased sharply. Compounds
with stoichiometric oxygen (x � 0.65) are hard,
strongly anisotropic magnets. The coercive force
HC at helium temperature reaches 15 kOe, where-
as for the ferromagnetic oxidized compositions
HC = 100 Oe.
As compounds with bismuth content above 65%
may not be obtained in air, synthesis of solutions in
the range 0.7 � �x 1 is performed at high pressures.
We have found out that the Curie temperature in-
creases smoothly with increase of bismuth content
from 87 K (x � 0.65) up to 108 K for BiMnO3. The
spontaneous magnetization grows sharply on going
from a solution with x � 0.8 to a solution with
x � 0.9. It is necessary to note that the growth of
the spontaneous magnetization correlates with a
change of the unit cell symmetry type from ortho-
rhombic (x � 0.8) to monoclinic (x � 0.9).
Measurements of the electrical conductivity are
carried out in a temperature range of 77–350 K. All
of the compounds under study had a semiconductor
character of the temperature dependence of the
electrical resistance. Near the temperature of mag-
netic ordering for structures with x � 0.4 a maxi-
mum of the magnetoresistance was observed (up to
40% in a field 9 kOe), but magnetic ordering did
not change the type of the conductivity.
Figure 5 presents the magnetic phase diagram of
the La1–xBixMnO3,07 system with an excess of oxy-
gen. The ferromagnetic state is gradually destroyed
with increase of the bismuth content, until in the
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 793
Magnetic phase transitions in the system La1–x
Bi
x
MnO3+�
Fig. 5. Magnetic phase diagram of the La1-xBixMnO3.07
system. P – paramagnetic state, F – ferromagnetic,
SG – spin glass.
Fig. 6. Magnetic phase diagram of the La1–xBixMnO3
system. WF — weak ferromagnetic state, Ð —
paramagnetic, F — ferromagnetic.
solution with x � 0.65 the state of the cluster-type
spin glass is not stabilized.
The magnetic phase diagram of the stoichio-
metric structures La1-xBixMnO3 is shown in Fig. 6.
LnMnO3 is a weak ferromagnet with Néel tempera-
ture TN � 144 K. With increase of the bismuth con-
tent up to x � 0.65 the stoichiometric structures
still show the properties inherent to a weak ferro-
magnet. The Néel temperature gradually decreases
to 87 K (x � 0.65), apparently is because of a de-
crease of the Mn–O–Mn bond angles. The lower
the Mn–O–Mn angle, the lower are the width of
the 3d band and the temperature of magnetic order-
ing [18–21]. It is well known that in LaMnO3
antiferrodistortion ordering of the dz2 orbitals oc-
curs in the ab plane as the exchange interaction be-
comes ferromagnetic in this plane and antifer-
romagnetic along the c axis [18]. The magnetic
moments are oriented along the b axis. In Bi-substi-
tuted stoichiometric manganites (õ
0.6) another
type of antiferromagnetic and orbital ordering is in
principle possible. However, in order to ascertain
the features of the magnetic and structural state,
neutron diffraction studies are required. In bismuth
manganite the orbital state dx y2 2�
is stabilized,
leading to an isotropic ferromagnetic state [14,21].
BiMnO3 is a soft magnetic material, despite the or-
bital ordering [14,22]. In solutions with a high bis-
muth content the magnetic state is most likely a
two-phase one. The sample consists of ferromag-
netic and antiferromagnetic areas. We believe that
each type of magnetic state is characterized by its
own type of orbital state.
It is well known that in manganites the substitu-
tion of the rare-earth ions R3+ and La3+ by an alka-
line-earth ion results in orbital disordering and sta-
bilization of the ferromagnetic state. This process is
caused by two factors. First, vacancies appear in
the orbitally ordered lattice (not Jahn–Teller ions
Mn4+), and that destabilizes a cooperative orbital
ordering. Second, distortions of the crystal lattice
decrease due to optimization of the cation’s sizes,
whereas the Mn–O–Mn bond angle which descri-
bes the width of the 3d band, is increased. Under
these conditions the static Jahn–Teller distortions
transform to dynamic ones, and the exchange inter-
actions of the Mn3+–O–Mn3+ and Mn3+–O–Mn4+
types become ferromagnetic [18]. The establish-
ment of magnetic order in structures with a large
enough width of the 3d band leads to transition in
metallic state due to overlapping of the bands
formed mainly by 3d and 2ð states.
In manganites containing a large quantity of
Bi3+ ions the appearance of tetravalent ions of man-
ganese does not induce ferromagnetism (Fig. 3).
The presence of Mn4+ ions promotes the destruction
of cooperative orbital ordering and the occurrence
of properties inherent to spin glasses. Thus the
compounds remain insulators. We believe that in
compounds with a large content of Bi3+ ions the lo-
cal static Jahn–Teller distortions are not removed.
This is explained by the tendency of Bi3+ ions to
form strongly anisotropic covalent ps bonds. These
bonds promote local crystal structure distortions,
which is the reason why the local Jahn–Teller or-
bital ordering is preserved. Indeed, the tempera-
ture of the charge and orbital ordering in
Bi0.5Sr0.5MnO3 is unusually high, above 500 K
[23,24], whereas the characteristic temperature of
charge and orbital ordering in the structures
R0.5Sr0.5MnO3 is 150 K [25,26]. Due to the local
static Jahn–Teller distortions, the anisotropic cha-
racter of the exchange interactions between the
manganese ions persist. On the other hand, in these
samples, due to fluctuations of the composi-
tion, microareas may exist in which the static
Jahn–Teller distortions are removed. These micro-
areas are ferromagnetic. The competition between
ferromagnetism and antiferromagnetism results in a
spin glass state of a cluster type. It should be noted
that orbital and charge ordering in manganites are
transitions of the martensitic type [27,28]. There-
fore orbitally two-phase states in manganites
should be realized at the concentration and tempe-
rature boundaries of the orbital order–disorder
transitions.
Summary
The crystal structure and magnetic properties of
both oxidized La1-xBixMnO3.07 and reduced
La1-xBixMnO3 perovskites have been studied. It is
shown that oxidized La1-xBixMnO3.07 series exhibit
a concentration transition from ferromagnetic state to
spin glass at x � 0.65 whereas reduced La1-xBixMnO3
perovskites transform from weak ferrimagnet state
to ferromagnetic one at x � 0.7 through a mixed
magnetic state. The results obtained are discussed
in terms of interplay between orbital ordering and
type of magnetic ground state.
This work was supported in part by the Belarus
Fund of Basic Research (Project F00-223).
794 Fizika Nizkikh Temperatur, 2002, v. 28, No. 7
I. O. Troyanchuk, O. S. Mantytskaja, H. Szymczak, and M. Yu. Shvedun
1. K. I. Kugel and D. I. Khomskii, Usp. Fiz. Nauk
136, 621 (1982) [Sov. Phis. Usp. 25, 231 (1982)].
2. V. Eremenko, S. Gnatchenko, N. Makedonska,
Yu. Shabakayeva, M. Shvedun, V. Sirenko, J. Fink-
Finowicki, K. Kamenev, G. Balakrishnan, and
P. Mck Paul, Fiz. Nizk. Temp. 27, 1258 (2001)
[Low Temp. Phys. 27, 930 (2001)].
3. R. Mahendiran, M. R. Ibarra, F. Maigan, A. Aru-
lraj, R. Mahesh, O. Revcau, and C. N. R. Rao,
Phys. Rev. Lett. 82, 2191 (1999).
4. P. M. Woodward, D. E. Cox, T. Vogt, C. N. Rao,
and A. K. Cheetham, Chem. Mater. 11, 3528 (1999).
5. I. O. Shklyarevskiy, M. Yu. Shvedun, S. L. Gnat-
chenko, P. J. M. van Bentum, P. C. M. Christia-
nen, J. C. Maan, K. V. Kamenev, G. Balakrishnan,
P. Mck Paul, and J. Fink-Finowicki, Fiz. Nizk.
Temp. 27, 1250 (2001) [Low Temp. Phys. 27, 923
(2001)]
6. I. O. Troyanchuk, D. A. Efimov, V. V. Eremenko,
V. A. Sirenko, H. Szymszak, and A. Nabialek, Fiz.
Nizk. Temp. 26, 39 (2000) [Low. Temp. Phys. 26,
28 (2000)].
7. V. V. Eremenko, V. A. Sirenko, H. Szymszak, and
A. Nabialek, Fiz. Nizk Temp. 25, 311 (1999) [Low
Temp. Phys. 25, 221 (1999)].
8. V. M. Loktev and Yu. G. Pogorelov, Fiz. Nizk.
Temp. 26, 231 (2000) [Low Temp. Phys. 26, 171
(2000)].
9. M. R. Ibarra, P. A. Alagarabel, C. Marguina,
J. Blasco, and J. Garsia, Phys. Rev. Lett. 75, 3541
(1995).
10. S. Quezel-Ambrunaz, Bull. Soc. Fr. Mineral et
Crystallogr. 91, 339 (1968).
11. F. Sugawara, S. Iida, Y. Syono, and S. Akimoto, J.
Phys. Soc. Jpn. 20, 1529 (1965).
12. V. A. Bokov, N. A. Milnikova, S. À. Kizhaev,
M. F. Brizhina, and I. À. Grigoryan. Fiz. Tverd.
Tela 7, 3695 (1965) (in Russian).
13. G. H. Jonker and J. H. van Santen, Physica 16,
337 (1950).
14. I. O. Troyanchuk, N. V. Kasper, O. S. Mantyt-
skaya, and S. N. Pastushonok, Sov. Phys. JETP 78,
212 (1994).
15. I. O. Troyanchuk, N. V. Samsonenko, E. F. Sha-
povalova, I. M. Kolesova, and H. Szymczak, J. Phys.:
Condens. Matter. 8, 11205 (1996).
16. H. Chiba, T. Atou, and Y. Syono, J. Solidi Status
Chem. 132, 139 (1997).
17. J. A. M. van Roosmalen and E. H. P. Cordfunke,
J. Solid. State Chem. 110, 109 (1994).
18. D. Gudenaf, Magnetizm i himicheskaya svyaz, Me-
talurgiya, Moskva (1968) (in Russian).
19. P. G. De Gennes, Phys. Rev. 18, 1, 141 (1960).
20. E. E. Havinga, Philips Res. Rep. 21, 432 (1966).
21. T. Atou, H. Chiba, K. Ohoyama, Y. Yamagnuchi,
and Y. Syono, J. Solid. State Chem. 145, 639 (1999).
22. I. Î. Troyanchuk and V. N. Derkachenko, Fiz.
Tverd. Tela 32, 2474 (1990) (in Russian).
23. N. V. Kasper, I. O. Troyanchuk, A. N. Chobot,
H. Szymczak, and J. Fink-Finowicki, J. Phys.: Con-
dens. Matter. 9, 7455 (1997).
24. J. L. Carcia-Munos, C. Froutera, M. A. G. Aranda,
A. Liobet, and C. Ritter, Phys. Rev. B63, 064415
(2001).
25. F. Millange, S. de Brion, and G. Chouteau, Phys.
Rev. B62, 9, 5619 (2000).
26. H. Kuwahara, Y. Tomioka, A. Asamitsu, Y. Mo-
ritomo, and Y. Tokura, Science 270, 961 (1995).
27. V. Podzorov, B. G. Kim, V. Kiryukhin, M. E.
Gershenson, and S-W. Cheong, Phys. Rev. B64,
140406 (2001).
28. I. O. Troyanchuk, A. I. Akimov, L. A. Bliznjuk,
and N. V. Kasper, J. Alloys and Compounds 228, 83
(1995).
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 795
Magnetic phase transitions in the system La1–x
Bi
x
MnO3+�
|