Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄
We describe the results of electronic Raman scattering experiments in two differently doped single crystals of La₂₋xSrxNiO₄ (x=0.225 and 1/3). In B₁g symmetry a crossover from weakly interacting to pseudogap-like behavior is observed at a charge-ordering temperature Tco. In B₂g symmetry a redistribu...
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Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України
2002
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| Cite this: | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ / V.P. Gnezdilov, Yu. G. Pashkevich, A.V. Yeremenko, P. Lemmens, G. Güntherodt, J.M. Tranquada, D.J. Buttrey, K. Nakajima // Физика низких температур. — 2002. — Т. 28, № 7. — С. 716-723. — Бібліогр.: 33 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859954802111283200 |
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| author | Gnezdilov, V.P. Pashkevich, Yu. G. Yeremenko, A.V. Lemmens, P. Güntherodt, G. Tranquada, J.M. Buttrey, D.J. Nakajima, K. |
| author_facet | Gnezdilov, V.P. Pashkevich, Yu. G. Yeremenko, A.V. Lemmens, P. Güntherodt, G. Tranquada, J.M. Buttrey, D.J. Nakajima, K. |
| citation_txt | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ / V.P. Gnezdilov, Yu. G. Pashkevich, A.V. Yeremenko, P. Lemmens, G. Güntherodt, J.M. Tranquada, D.J. Buttrey, K. Nakajima // Физика низких температур. — 2002. — Т. 28, № 7. — С. 716-723. — Бібліогр.: 33 назв. — англ. |
| collection | DSpace DC |
| container_title | Физика низких температур |
| description | We describe the results of electronic Raman scattering experiments in two differently doped single crystals of La₂₋xSrxNiO₄ (x=0.225 and 1/3). In B₁g symmetry a crossover from weakly interacting to pseudogap-like behavior is observed at a charge-ordering temperature Tco. In B₂g symmetry a redistribution of electronic continua with decreasing temperature is accompanied by a loss of spectral weight below Tco in the low-frequency region due to opening of a pseudogap. The slope of the Raman response at vanishing frequencies is investigated, too. Its temperature behavior in B₂g symmetry, which predominantly selects charge carriers with momenta along the diagonals of the NiO₂ bonds, provides clear evidence for one-dimensional charge transport in the charge-ordered phase.
|
| first_indexed | 2025-12-07T16:19:18Z |
| format | Article |
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Fizika Nizkikh Temperatur, 2002, v. 28, No. 7, p. 716–723
Electronic Raman scattering through a stripe ordering
transition in La Sr NiO2 4�x x
V. P. Gnezdilov1, Yu. G. Pashkevich2, A. V. Yeremenko1, P. Lemmens3,
G. Güntherodt4, J. M. Tranquada4, D. J. Buttrey5, and K. Nakajima6
1B. Verkin Institute for Low Temperature Physics and Engineering of the National Academy of
Sciences of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine
E-mail:gnezdilov@ilt.kharkov.ua
2A. Galkin Donetsk Physico-Technical Institute of the National Academy of Sciences of Ukraine,
72 R. Luxemburg Str., Donetsk 83114, Ukraine
3Physikalisches Institut, RWTH Aachen, Aachen 52056, Germany,
4Brookhaven National Laboratory, Upton, NY 11973,
5University of Delaware, Newark, Delaware 19716,
6Neutron Scattering Laboratory ISSP, University of Tokyo, Tokai, Ibaraki, Japan
Received February 28, 2002
We describe the results of electronic Raman scattering experiments in two differently
doped single crystals of La Sr NiO2 4�x x (x � 0.225 and 1/3). In B g1 symmetry a crossover from
weakly interacting to pseudogap-like behavior is observed at a charge-ordering temperature
Tco . In B g2 symmetry a redistribution of electronic continua with decreasing temperature is
accompanied by a loss of spectral weight below Tco in the low-frequency region due to opening
of a pseudogap. The slope of the Raman response at vanishing frequencies is investigated, too.
Its temperature behavior in B g2 symmetry, which predominantly selects charge carriers with
momenta along the diagonals of the NiO2 bonds, provides clear evidence for one-dimensional
charge transport in the charge-ordered phase.
PACS: 78.30.–j
Introduction
Stripe ordering of charge and spin in transi-
tion-metal oxides has been of intense interest to
condensed-matter physics from the theoretical and
experimental points of view as an example of a
nontrivial ordering phenomenon that originates
from the interplay between charge hybridization
and interaction. The first evidence for unusual mag-
netic correlations was obtained in a neutron diffrac-
tion study on a single crystal of La1.8Sr0.2NiO3.96
[1]. Indications of charge order in La Sr NiO2 4�x x
were found in electron diffraction [2] and transport
measurements [3] on ceramic samples. Neutron dif-
fraction studies [4,5] of a La2NiO4.125 crystal were
the first to detect diffraction from both the mag-
netic and charge order in the same sample. In the
first studies of La Sr NiO2 4�x x it has been suggested
that ordering of the dopant-induced holes occurs
only commensurately at special values of x, such as
1/2 and 1/3 [2,3]. Later it was found that a single
crystal with x � 0.2, although not at a special value
of x, shows commensurate order [6], albeit with a
short in-plane correlation length of ~ 40 Å. In con-
trast, the stripe order in La NiO2 4�� [4,5] and
La1.775Sr0.225NiO4 [7] was found to be incommen-
surate, with the wave vector varying significantly
with temperature.
The stripe order in Sr-doped nickelates has been
characterized in detail by neutron diffraction, and
some summary of the results is given in Ref. 8.
While many features of the ordering are now clear,
© V. P. Gnezdilov, Yu. G. Pashkevich, A. V. Yeremenko, P. Lemmens, G. Güntherodt, J. M. Tranquada, D. J. Buttrey, and
K. Nakajima, 2002
some questions remain. One of them is the question
of the possibility of finite conductivity in the stri-
pe-ordered state. One can expect two possible sce-
narios, which could lead to conductivity. Accord-
ing to the first one the stripes themselves are
insulating but the system can be metallic due to
fluctuations and motion of stripes [9]. Alterna-
tively, metallic conductivity may exist along the
charge threads without a violation of stripe order-
ing as a whole. In the latter case, Coulomb interac-
tions between neighboring stripes should lead to
charge-density-wave order along stripes at suffi-
ciently low temperatures and in the absence of
stripe fluctuations [10]. In our previous optical
conductivity study of a La1.775Sr0.225NiO4 single
crystal a strong Fano antiresonance was observed in
the optical conductivity spectra [11]. Based on a
careful analysis of the phonon spectra, we con-
cluded that the energy of the antiresonance corre-
sponds to Ni–O bond stretching motions along the
stripes. It was concluded that the antiresonance,
which results from electron–phonon coupling, pro-
vides strong evidence for finite conductivity along
the stripes in the incommensurately stripe-ordered
sample, at least at optical-phonon frequencies.
Raman scattering (RS) is a powerful method for
studying the excitations of charge carriers in solids.
In recent years this method has been widely applied
to study the scattering of electrons in metals, insu-
lators, semiconductors, and superconductors. Via
light’s coupling to the electron’s charge, inelastic
light scattering reveals symmetry-selective proper-
ties of the electron dynamics over a wide range of
energy scales and temperatures. In this work we re-
port on electronic Raman scattering spectra of two
La2–xSrxNiO4 single crystals with x � 0.225 and
x � 1/3 and with charge ordering temperatures
Tño � 150 K and 240 K, respectively [7,12]. The
hole density per Ni site in the sample with x � 0.225
is less than 1 (in contrast to x � 1/3, where the
density is exactly 1). It is known that in-plane re-
sistivity �ab of Sr-doped lantanium nickelates is
doping-dependent: it increases with hole concentra-
tion decreasing. And independently of the doping
level, the resistivity increases by several orders be-
low Tco [3,13,14], which indicates quenching of the
charge degrees of freedom due to the ordering. At
first glance the increase of the resistivity below Tco
is incompatible with possible conductivity along
the threads of the stripes, which remain in the char-
ge-ordered state. This contradiction can be removed
by stripe domain formation, which occurs below
Tco . One can expect the appearance of two type
thermodynamical stripe-domains in which stripes
run perpendicular to each other. Thus, only small
part of the threads of charges can participate in the
charge transfer. Three principal symmetries A g1 ,
B g1 , and B g2 , were examined. As has been de-
scribed in detail in other publications [15–19],
there exists a relationship between the charge-car-
rier momenta and light polarization through the
symmetry properties of the Raman vertex. In B g1
and B g2 symmetry the charge carriers with mo-
menta along the principal axes and the diagonals,
respectively, are preferentially weighted. A g1 is a
weighted average over the entire Brillouin zone.
Experiment
Raman spectra were measured on fresh chemi-
cally etched surfaces in a quasi-backscattering con-
figuration utilizing a triple monochromator
(DILOR XY), a liquid nitrogen cooled CCD detec-
tor, and a 514.5-nm Ar-ion laser. The laser beam of
20 mW was focused on an area of 0.1 mm2 on the
ab plane of the mirrorlike polished crystal surface.
The orientation of the crystals in the I mmm4 set-
ting was monitored by x-ray Laue diffraction.
All measurements were performed with the po-
larization of incident and scattered light as
( ) = ( )� , �E Ei s xx , (xy), and (ab), respectively. Here
a � [100] and b � [010] are directions along the
Ni–O–Ni bonds; the x and y directions are parallel
to [110] and [ ]110 . Such geometries allow measur-
ing the A g1 + B g2 , B g1 , and B g2 symmetry compo-
nents of the Raman-scattering cross section. The
Raman response functions ��� �( ) were obtained by di-
viding the original spectra I T( , )� by Bose–Einstein
thermal factor, since they are related to each other
through I T k TB( , ) ~ [ exp ( )] ( , )� � � �1 1� � ���
� .
Results and discussion
Raman scattering spectra of La Sr NiO2 4�x x
(x � 1/3, 0.225) and La2NiO4.125 in the xx and xy
scattering geometries are presented elsewhere
[11,20–22]. The average symmetry of the lattice is
described by space group I4/mmm. The correspon-
ding Raman-active phonons are distributed among
the irreducible representations of the space group
as 2A g1 + 2Eg . At room temperature all the ob-
served modes are weak and broad. Conspicuous
changes were observed in the phonon spectra below
the charge-ordering temperature Tco . The occur-
rence of stripe order, with a characteristic wave
vector Qc , lowers the translational symmetry and
leads to the appearance of extra lines both in the xx
and xy spectra. Low-temperature scans in the xy
geometry reveal also two wide bands that were in-
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 717
Electronic Raman scattering through a stripe ordering transition in La Sr NiO2 4�x x
terpreted as two-magnon excitations within the
antiferromagnetic domains and across the domain
walls [11,20–22]. Phonon and two-magnon excita-
tions are superposed on top of a significant electro-
nic background that changes its shape with chang-
ing temperature.
As was noted in Ref. 23, RS experiments in
strongly correlated systems (ranging from mixed-
valence materials to Kondo insulators to high-tem-
perature superconductors) show temperature-de-
pendent electronic Raman spectra that are both re-
markably similar and quite anomalous, suggesting a
common mechanism governing transport. While
theories that describe RS in weakly correlated me-
tals [18] and band insulators [24] have been known
for some time, a theory that connects the metallic
and insulating states and describes materials near
the metal–insulator transition has been developed
only recently [23]. The theoretical model contains
two types of electrons: itinerant band electrons and
localized (d or f) electrons. The band electrons can
hop between nearest neighbors (with hopping inte-
gral t*/(2 d) on a d-dimensional cubic lattice),
and they interact via screened Coulomb interaction
with the localized electrons (which is described by
an interaction strength U between electrons that
are located at the same lattice site). The Hamil-
tonian is written as
H
t
d
d d E wi j
i j
f i
i
� � � �
*
( , )2
†
� � �
( )d d w U d d wi i i
i
i i i
i
† † ,
where di
†(di) is the spinless conduction electron
creation (annihilation) operator at lattice site i and
wi = 0 or 1 is a classical variable corresponding to
the localized f-electron number at site i. Both Ef
and
were adjusted so that the average filling
of the d electrons is 1/2 and the average filling of
the f electrons is 1/2 (
� U/2 and Ef = 0). For
half-filling, U < 0.65 corresponds to a weakly
correlated metal, while a pseudogap phase appears
for 0.65 < U < 1.5, passing through a quantum
critical point at U = 1.5 to the insulator phase
U > 1.5 (the values of U are presented in units
of t*).
Figures 1,a and 2,a show the A g1 experimental
Raman spectra for the samples under study at dif-
ferent temperatures, that were obtained by sub-
tracting the (ab) spectra from the (xx) ones. Figu-
res 1,b and 2,b present the electronic Raman
response for the A g1 channel evaluated at different
temperatures by fitting the experimental curves
and it is seen that the general behavior of the A g1
response is similar for both samples. As follows
from the theory [23], the A g1 Raman response has a
718 Fizika Nizkikh Temperatur, 2002, v. 28, No. 7
V. P. Gnezdilov et al.
Fig. 1. Experimental A1g Raman response of
La1.775Sr0.225NiO4 at different temperatures (T = 5, 50,
100, 150, 200, and 295 K from top to bottom). The
spectra are plotted on the same scale but are displaced
vertically for clarity (a). Electronic A1g Raman response
at the same temperatures evaluated from the experimen-
tal spectra (b).
Fig. 2. Experimental A1g Raman response of
La5/3Sr1/3NiO4 at different temperatures (T = 5, 50,
100, 150, 250, and 295 K from top to bottom). The
spectra are plotted on the same scale but are displaced
vertically for clarity (a). Electronic A1g Raman response
at the same temperatures evaluated from the experimen-
tal spectra (b).
bell-like shape at all values of U and increases and
sharpens as U increases. The peak of the response
becomes more symmetric in shape and moves to
higher energies also. Above Tco , our samples dis-
play behavior consistent with the theory [23] and
resistivity measurements [3,13,14]: (i) the Raman
response function has an asymmetric line shape
characteristic for U < 1.5; (ii) the peak position
shifts to lower energy with increasing hole concen-
tration (decreasing resistivity).
Below Tco , the A g1 Raman responses change to
shapes composed of a rapidly increasing part from
� ~ 0 to the leading edge energies and a weakly
�-dependent part above them. The position of the
leading edge depends on the temperature and shifts
to higher energy as the temperature decreases.
In Figures 3,a and 4,a we plot (xy) spectra ver-
sus temperature. Figures 3,b and 4,b present the
electronic Raman response for the B g1 channel
evaluated from the experimental spectra. In the
charge-disordered state (above Tco) the B g1 elec-
tronic Raman spectra for both samples are close to
the ideal «bad metal» spectra. Note that the magni-
tude of resistivity above Tco corresponds to a «bad
metal» also. As the temperature crosses Tco , dra-
matic changes are observed in the spectra: the
low-frequency response depletes and the spectral
weight shifts into a charge-transfer peak. The posi-
tion of the charge-transfer peak for the sample with
x � 0.225 was estimated as ~ 840 cm–1 at T = 5 K.
The same charge gap value was obtained from the op-
tical conductivity spectra [11]. For the sample with
x � 1/3, a surprisingly lower position (~ 900 cm–1)
of the charge transfer peak was observed in our
Raman experiments in comparison with the value
of 2090 cm–1 for the charge gap from the optical
conductivity measurements [25].
Summarizing the comparison of our results with
the theoretical calculations [23], one may to con-
clude that the B g1 response for both measured sam-
ples below Tco has a line shape that is closer to the
pseudogap phase than to the strong insulator phase.
Concerning the temperature behavior, the decreas-
ing of the spectral weight and the shift of the peak
position to a higher energy with a decreasing tem-
perature are contrary to the theoretical predictions.
It seems that the inclusion of a strong interaction
between electrons and spin fluctuations [26] or the
scattering of electrons on extended impurities [27]
into the theory could resolve this discrepancy.
Additional information on charge dynamics can
be obtained from the slope of ��� ��� at vanishing fre-
quencies. This slope can be denoted as
� �
� ��
�
lim ( )
w
w
0
� �� , where � � B g1 or B g2 . As is clearly
seen in Fig. 5, the slope of the low-energy continua
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 719
Electronic Raman scattering through a stripe ordering transition in La Sr NiO2 4�x x
Fig. 3. Experimental B1g Raman response of
La1.775Sr0.225NiO4 at different temperatures (T = 5, 50,
100, 150, 200, 250, and 295 K from top to bottom). The
spectra are plotted on the same scale but are displaced
vertically for clarity (a). Electronic A1g Raman response
at the same temperatures evaluated from the experimen-
tal spectra (b).
Fig. 4. Experimental B1g Raman response of
La5/3Sr1/3NiO4 at different temperatures (T = 5, 50,
150, 200, 250, and 295 K from top to bottom). The
spectra are plotted on the same scale but are displaced
vertically for clarity (a). Electronic A1g Raman respon-
se at the same temperatures evaluated from the experi-
mental spectra (b).
for both samples changes with decreasing tempera-
ture. The inverse Raman slope characterizes the
quasiparticle lifetime at regions of the Fermi sur-
face selected by the light polarization orientations.
In earlier publications [23,28] it was shown that
the inverse slope 1
� shows qualitatively different
behavior for different doping regimes of various
cuprate materials. At B g1 symmetry a strong doping
dependence of the inverse slope was observed [28].
In Fig. 6,a we plot the inverse slope of the Raman
response obtained from the B g1 experimental spec-
tra. The variation of the inverse slope with tempe-
rature for the x � 0.225 sample clearly shows the
pseudogap phase behavior, while for the x � 1/3
sample the low-temperature inverse slope increases
dramatically, as is characteristic for a more insulat-
ing system.
We turn now to the temperature dependence of
the B g2 response in our samples. Our interest is
connected with the attempt to observe a pseudogap
in the RS spectra. The term pseudogap denotes a
partial gap. An example of such a partial gap
would be a situation where, within the band theory
approximation, some regions of the Fermi surface
become gapped while other parts retain their con-
ducting properties [29]. A number of families of
high-temperature cuprate oxides demonstrate evi-
dence of the presence of a pseudogap in the normal
state. As was convincingly proved in Ref. 30, the
pseudogap is a signature of the electronic interac-
tions above Tc and is not directly related to the
superconducting pairing correlations. In the RS ex-
periments on high-Tc cuprates the pseudogap state
is characterized by a loss of spectral weight in the
frequency range between zero and approximately
800 cm–1 and is clearly seen in B g2 symmetry in
underdoped materials. The change of the spectra in
the pseudogap state becomes very small for higher
doping levels.
Figure 7 shows the B g2 Raman response in
La Sr NiO2 4�x x at two doping levels, obtained at
temperatures of 295 K and 5 K. The loss of spectral
weight in the low-frequency region on cooling is
seen. To make things more quantitative we carried
out measurements at different temperatures, and
the results are shown in Figs. 8 and 9. For clarity
the two temperature ranges are plotted separately.
Above the charge-ordering temperature no intensity
720 Fizika Nizkikh Temperatur, 2002, v. 28, No. 7
V. P. Gnezdilov et al.
Fig. 5. Low-frequency B1g Raman response of
La1.775Sr0.225NiO4 (a) and La5/3Sr1/3NiO4 (b) single
crystals obtained at temperatures 5, 50, 100, 150, 200,
250, and 295 K (from top to bottom). The dashed lines
in the figures represent the slope of ��� �( ) as �� 0.
Fig. 6. Inverse slope of the B1g (a) and B2g (b). Ra-
man response obtained from the experimental spectra of
La1.775Sr0.225NiO4 and La5/3Sr1/3NiO4 single crystals.
anomalies occur (Figs. 8,a, 9,a). For T < Tco spec-
tral weight is lost in the low-frequency region. In
Fig. 10 we plot the difference � �� ��� �� � � � �� � �, ,T T
� � �� ��� �,T Tco between the spectra measured at
different temperatures below Tco and the spectrum
obtained just above Tco . We observe the maximal
amplitude of the spectral change at approxima-
tely 300 cm–1 (x � 0.225) and 250 cm–1 (x � 1/3)
(Figs. 8,b, 9,b). However, for a detailed analysis of
Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 721
Electronic Raman scattering through a stripe ordering transition in La Sr NiO2 4�x x
Fig. 7. Experimental B2g Raman response of
La1.775Sr0.225NiO4 (a) and La5/3Sr1/3NiO4 (b) single
crystals measured at temperatures above and below
charge-ordering temperature in the frequency region 0 –
1300 cm–1.
Fig. 8. B2g spectra for La1.775Sr0.225NiO4 . The upper
panel shows spectra at T > Tco (a). The spectra are dis-
placed for clarity and their zeros are indicated by a tick
on the vertical axis. The lower panel shows spectra at
T < Tco (b).
Fig. 9. B2g spectra for La5/3Sr1/3NiO4 . The upper
panel shows spectra at T Tco� (a). The spectra are
displaced for clarity and zero for the spectra at 295 K is
indicated by a tick on the vertical axis. The low panel
shows spectra at T Tco� (b).
Fig. 10. The pseudogap as a function of temperature.
Shown in the figure are differences between the respon-
se functions at T < Tco and response function just above
Tco .
the pseudogap state it would be more physical to
relate the «normal» and «pseudogap» spectra at the
same temperature as was done in Ref. 30, where the
«normal» spectra at the respective temperatures
were constructed. Although the pseudogap has been
observed and investigated by various methods, its
interpretation is still an open issue at present. In
Refs. 30,31 it was speculated that as the energy
scale of the pseudogap is comparable to that of the
exchange interaction J, the driving force is mag-
netic.
While the B g1 data cannot be linked to ordinary
transport, the inverse slope observed in the B g2
channel was found to track the temperature de-
pendence of the dc resistivity [28,30]. Moreover,
the B g2 response is expected to be sensitive to pro-
perties of charge stripes running along the diagonal
directions between in-plane Ni–O bonds. In Fig. 11
the low-frequency B g2 spectra at different tempera-
tures are shown. It is seen that the slope of the
Raman response for both samples is temperature de-
pendent. The temperature dependences of the in-
verse slope in the B g2 channel are presented in
Fig. 6,b, which indicates that below Tco , 1
� de-
creases with decreasing temperature for both sam-
ples. Such metal-like behavior of the inverse Ra-
man slope demonstrates the existence of finite
conductivity within the charge stripes. A crossover
from two-dimensional to one-dimensional transport
behavior due to the formation of stripes was pro-
posed by Moshalkov et al. [32]. Direct evidence for
one-dimensional transport in the stripe-ordered
phase was demonstrated in Hall coefficient mea-
surements on neodymium-doped lanthanum stron-
tium cuprate [33].
In summary, channel-dependent Raman scatter-
ing measurements of La Sr NiO2 4�x x (x � 0.225,
1/3) samples were carried out over a wide range of
temperatures. It was found that the scattering on
charge carriers for both samples is quite similar.
For A g1 , B g1 , and B g2 symmetries a temperatu-
re-dependent redistribution of the electronic con-
tinua was observed for both compounds.
In the B g1 channel a crossover from the weakly
interacting to pseudogap-like behavior of the elec-
tronic continua was found at the charge-ordering
temperature. From the low-frequency B g1 spectra
we have estimated the B g1 inverse Raman slope. Its
temperature behavior is in agreement with the theo-
retical one for the pseudogap phase.
The pseudogap state that is characterized by a
loss of spectral weight in the low-frequency region
was directly observed in the B g2 symmetry below
Tco . The decrease of the inverse Raman slope below
Tco and its metal-like behavior provides evidence
for one-dimensional finite conductivity within the
charge stripes.
We are grateful to Prof. V.V. Eremenko for per-
manent interest and support of our activity and for
useful discussions. This work was supported by
the NATO Science Programme under Grant No
PST.CLG 977766.
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Fizika Nizkikh Temperatur, 2002, v. 28, No. 7 723
Electronic Raman scattering through a stripe ordering transition in La Sr NiO2 4�x x
|
| id | nasplib_isofts_kiev_ua-123456789-130241 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 0132-6414 |
| language | English |
| last_indexed | 2025-12-07T16:19:18Z |
| publishDate | 2002 |
| publisher | Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України |
| record_format | dspace |
| spelling | Gnezdilov, V.P. Pashkevich, Yu. G. Yeremenko, A.V. Lemmens, P. Güntherodt, G. Tranquada, J.M. Buttrey, D.J. Nakajima, K. 2018-02-09T11:12:58Z 2018-02-09T11:12:58Z 2002 Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ / V.P. Gnezdilov, Yu. G. Pashkevich, A.V. Yeremenko, P. Lemmens, G. Güntherodt, J.M. Tranquada, D.J. Buttrey, K. Nakajima // Физика низких температур. — 2002. — Т. 28, № 7. — С. 716-723. — Бібліогр.: 33 назв. — англ. 0132-6414 PACS: 78.30.-j https://nasplib.isofts.kiev.ua/handle/123456789/130241 We describe the results of electronic Raman scattering experiments in two differently doped single crystals of La₂₋xSrxNiO₄ (x=0.225 and 1/3). In B₁g symmetry a crossover from weakly interacting to pseudogap-like behavior is observed at a charge-ordering temperature Tco. In B₂g symmetry a redistribution of electronic continua with decreasing temperature is accompanied by a loss of spectral weight below Tco in the low-frequency region due to opening of a pseudogap. The slope of the Raman response at vanishing frequencies is investigated, too. Its temperature behavior in B₂g symmetry, which predominantly selects charge carriers with momenta along the diagonals of the NiO₂ bonds, provides clear evidence for one-dimensional charge transport in the charge-ordered phase. We are grateful to Prof. V.V. Eremenko for permanent interest and support of our activity and for useful discussions. This work was supported by the NATO Science Programme under Grant No PST.CLG 977766. en Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України Физика низких температур Магнетизм Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ Article published earlier |
| spellingShingle | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ Gnezdilov, V.P. Pashkevich, Yu. G. Yeremenko, A.V. Lemmens, P. Güntherodt, G. Tranquada, J.M. Buttrey, D.J. Nakajima, K. Магнетизм |
| title | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ |
| title_full | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ |
| title_fullStr | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ |
| title_full_unstemmed | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ |
| title_short | Electronic Raman scattering through a stripe ordering transition in La₂₋xSrxNiO₄ |
| title_sort | electronic raman scattering through a stripe ordering transition in la₂₋xsrxnio₄ |
| topic | Магнетизм |
| topic_facet | Магнетизм |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/130241 |
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