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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Published in:Физика низких температур
Date:2002
Main Authors: Gnezdilov, V.P., Pashkevich, Yu. G., Yeremenko, A.V., Lemmens, P., Güntherodt, G., Tranquada, J.M., Buttrey, D.J., Nakajima, K.
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Published: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2002
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Online Access:https://nasplib.isofts.kiev.ua/handle/123456789/130241
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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
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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.
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fulltext 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. 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Hoffmann, P. F. Mul- ler, R. Hackl, H. Berger, L. Forro, A. Erb, and E. Walker, Phys. Rev. Lett. 78, 4837 (1997). 32. V. V. Moshchalkov, L. Trappeniers, and J. Vana- cken, Europhys. Lett. 46, 75 (1999). 33. T. Noda, H. Eisaki, and Shin-ichi Uchida, Science 286, 265 (1999). 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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