The phase diagram and optical properties of La1−xSrxMnO3 for x⩽0.2

Paraskevopoulos, M.; Mayr, F.; Hartinger, Ch.; Pimenov, A.; Hemberger, J.; Lunkenheimer, P.; Loidl, A.; Mukhin, A. A.; Ivanov, V. Yu.; Balbashov, A. M.

doi:10.1016/s0304-8853(99)00722-2

Cited by 45 publications

(25 citation statements)

References 38 publications

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“…The coercitive field first increases from pure LaMnO 3 up to x = 0.1 and reduces to a very small value at x = 0.125. Similar observations were found in Sr doped samples 30,31 . Such an hysteresis cycle indicates a pinning of the magnetic domains to the lattice, which increases up to x=0.1 and disappears at x = 0.125.…”

Section: ) Magnetization Measurementssupporting

confidence: 77%

Approach to the metal-insulator transition inLa1−xCaxMnO<

et al. 2001

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We describe the evolution of the static and dynamic spin correlations of La1−xCaxMnO3, for x=0.1, 0.125 and 0.2, where the system evolves from the canted magnetic state towards the insulating ferromagnetic state, approaching the metallic transition (x=0.22). In the x=0.1 sample, the observation of two spin wave branches typical of two distinct types of magnetic coupling, and of a modulation in the elastic diffuse scattering characteristic of ferromagnetic inhomogeneities, confirms the static and dynamic inhomogeneous features previously observed at x<0.1. The anisotropic q-dependence of the intensity of the low-energy spin wave suggests a bidimensionnal character for the static inhomogeneities. At x=0.125, which corresponds to the occurence of a ferromagnetic and insulating state, the two spin wave branches reduce to a single one, but anisotropic. At this concentration, an anomaly appears at q0=(1.25,1.25,0), that could be related to an underlying periodicity, as arising from (1.5,1.5,0) superstructures. At x=0.2, the spin-wave branch is isotropic. In addition to the anomaly observed at q0, extra magnetic excitations are observed at larger q, forming an optical branch. The two dispersion curves suggest an anti-crossing behavior at some q0' value, which could be explained by a folding due to an underlying perodicity involving four cubic lattice spacings.

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Section: ) Magnetization Measurementssupporting

confidence: 77%

Approach to the metal-insulator transition inLa1−xCaxMnO<

et al. 2001

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“…In the region between 3 THz and 30 THz (12.5 < log 10 ν < 13.5), resonance-like features show up, typical for phononic excitations. As was also found for other perovskite-related materials (e.g., [17,18,22]), there are three main contributions, with peaks in σ'(ν) at about 5 THz, 10 THz, and 16 THz (≈ 170 cm -1 , 330 cm -1 , and 530 cm -1 , respectively). In cubic perovskites, ABO 3 , the three infraredactive phonon excitations are ascribed to external, bending, and stretching modes.…”

Section: Discussionmentioning

confidence: 75%

Apparent Giant Dielectric Constants, Dielectric Relaxation, and Ac‐Conductivity of Hexagonal Perovskites La_1.2Sr_2.7BO_7.33 (B: Ru, Ir).

et al. 2007

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We present a thorough dielectric investigation of the hexagonal perovskites La 1.2 Sr 2.7 IrO 7.33 and La 1.2 Sr 2.7 RuO 7.33 in a broad frequency and temperature range, supplemented by additional infrared measurements. The occurrence of giant dielectric constants up to 10 5 is revealed to be due to electrode polarization. Aside of dc and ac conductivity contributions, we detect two intrinsic relaxation processes that can be ascribed to ionic hopping between different offcenter positions. In both materials we find evidence for charge transport via hopping of localized charge carriers. In the infrared region, three phonon bands are detected, followed by several electronic excitations. In addition, these materials provide further examples for the occurrence of a superlinear power law in the broadband ac conductivity, which recently was proposed to be a universal feature of all disordered matter.

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“…7 It has been recently observed that the application of large magnetic fields or pressures favors the charge ordered state of the OЉ phase at the expense of the metallic state of the OЈ phase. [9][10][11][12][13][14] Hence, the magnetic field and pressure increase the T O Ј O Љ transition temperature, i.e., they stabilize the OЉ phase. An antiferromagnetic-type orbital ordering was sug-gested to take place in the OЉ phase, which would lead to ferromagnetic superexchange interactions.…”

Section: Introductionmentioning

confidence: 99%

Paramagnetic behavior and correlation between high- and low-temperature structural and magnetic transitions inLa1−xSrx
Nogués
¹
,
Skumryev
²
,
Muñoz
³

et al. 2001
Phys. Rev. B
13
2
9
0
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The paramagnetic properties of La 1Ϫx Sr x MnO 3 (xϳ1/8) single-crystal perovskites have been studied. The effective moments e f f obtained from fits to the Curie-Weiss law in the paramagnetic regime are strongly enhanced from their theoretical values, both above and below the pseudocubic orthorhombic (O-OЈ) Jahn-Teller ͑JT͒ transition. This indicates the presence of clusters and that this clustering is not induced or affected by the JT transition. The e f f values in the O and OЈ phases are very similar, however, their paramagnetic Curie temperatures are rather different, implying that the JT distortion only induces a change in the exchangecoupling parameters but not in the character of the clusters. The correlation between the high-temperature paramagnetic and low-temperature ferromagnetic parameters suggests that the O and OЉ phases are not only analogous structurally but have also comparable exchange-coupling parameters and are consequently similar magnetically. Finally, the competition between the JT distortion, the magnetic field, and the molecular field, among other factors, apparently governs the properties of these systems.

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The phase diagram and optical properties of La1−xSrxMnO3 for x⩽0.2

Cited by 45 publications

References 38 publications

Approach to the metal-insulator transition inLa1−xCaxMnO<

Approach to the metal-insulator transition inLa1−xCaxMnO<

Apparent Giant Dielectric Constants, Dielectric Relaxation, and Ac‐Conductivity of Hexagonal Perovskites La_1.2Sr_2.7BO_7.33 (B: Ru, Ir).

Paramagnetic behavior and correlation between high- and low-temperature structural and magnetic transitions inLa1−xSrx
Nogués
¹
,
Skumryev
²
,
Muñoz
³

et al. 2001
Phys. Rev. B
13
2
9
0
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The phase diagram and optical properties of La1−xSrxMnO3 for x⩽0.2

Cited by 45 publications

References 38 publications

Approach to the metal-insulator transition inLa1−xCaxMnO<

Approach to the metal-insulator transition inLa1−xCaxMnO<

Apparent Giant Dielectric Constants, Dielectric Relaxation, and Ac‐Conductivity of Hexagonal Perovskites La1.2Sr2.7BO7.33 (B: Ru, Ir).

Paramagnetic behavior and correlation between high- and low-temperature structural and magnetic transitions inLa1−xSrxNogués1, Skumryev2, Muñoz3 et al. 2001Phys. Rev. B13290View full textAdd to dashboardCite

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Apparent Giant Dielectric Constants, Dielectric Relaxation, and Ac‐Conductivity of Hexagonal Perovskites La_1.2Sr_2.7BO_7.33 (B: Ru, Ir).

Paramagnetic behavior and correlation between high- and low-temperature structural and magnetic transitions inLa1−xSrx
Nogués
¹
,
Skumryev
²
,
Muñoz
³

et al. 2001
Phys. Rev. B
13
2
9
0
View full text Add to dashboard Cite