Direct Observation of Large Electronic Domains with Memory Effect in Doped Manganites

Sarma, D. D.; Topwal, D.; Manju, U.; Krishnakumar, S.; Bertolo, M.; Rosa, S. La; Cautero, G.; Koo, Tae‐Yeong; Sharma, Prakash Chandra; Cheong, Sang‐Wook; Fujimori, A.

doi:10.1103/physrevlett.93.097202

Cited by 91 publications

(70 citation statements)

References 12 publications

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“…This is in agreement with a unified picture pointing toward a "physics" of manganites over two different correlation lengths, namely, one at the atomic level, where the interaction is basically driven by the hopping integral, and the other at the nanoscale/ mesoscale, dominated by the interactions among domains belonging to different competing phases. In many mixed-valence manganite compounds, the occurrence and the magnitude of CMR peaks at the insulator to metal transition basically depend upon the small scale site-site interactions (25), although PS is also observed and plays a role (26,27). The DE mechanism (1) and the interplay with the JT distortion appear to capture the essence of this phenomenon.…”

Section: Significancementioning

confidence: 99%

Origin of colossal magnetoresistance in LaMnO ₃ manganite

Baldini

Muramatsu

Sherafati

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Phase separation is a crucial ingredient of the physics of manganites; however, the role of mixed phases in the development of the colossal magnetoresistance (CMR) phenomenon still needs to be clarified. We report the realization of CMR in a single-valent LaMnO 3 manganite. We found that the insulator-to-metal transition at 32 GPa is well described using the percolation theory. Pressure induces phase separation, and the CMR takes place at the percolation threshold. A large memory effect is observed together with the CMR, suggesting the presence of magnetic clusters. The phase separation scenario is well reproduced, solving a model Hamiltonian. Our results demonstrate in a clean way that phase separation is at the origin of CMR in LaMnO 3 .colossal magnetoresistance | strongly correlated materials | phase separation | high pressure | transport measurements I n hole-doped rare earth manganite compounds, the colossal magnetoresistance (CMR) peaks at a transition from a hightemperature (T) insulating paramagnetic phase to a low-T conducting ferromagnetic phase. The presence of Mn 3+ and Mn 4+ ions together with the site-site double-exchange (DE) mechanism (1) appear to capture the essence of this phenomenon. A plethora of experimental and theoretical investigations have recently suggested that the ground states of manganites are intrinsically inhomogeneous and characterized by the presence of competing phases (2-8) extending over domains at nanoscale/mesoscale. High pressure (P) has a triggering effect for phase separation because either magnetic or structural domains have been observed in compressed manganites (9-12). The role of the nanostructuring and of the interdomain interactions in the CMR phenomenon is still far from being completely understood, and to design materials that incorporate CMR at room temperature (RT) remains a challenge because of the strong interplay among electronic, structural, and magnetic interactions at both atomic and interdomain scales.As an archetypal cooperative Jahn-Teller (JT) system (13) and the parent compound of several important mixed-valence CMR manganite families, LaMnO 3 (LMO) is at the focus of intense investigations. Up to now, the CMR effect has been observed in hole-doped LMO, but not in single-valent LMO. At RT, LMO enters a high conductive phase above 32 GPa showing a "badmetal" behavior (14). Previous Raman spectroscopy study (9) shows the emergence, in compressed LMO, of a phase-separated (PS) state consisting of domains of JT-distorted and undistorted MnO 6 octahedra. The simultaneous presence of an inherent phase separation as well as of a metallization process resembles the conditions under which CMR is observed in doped compounds, and suggests the onset of CMR in compressed LMO. To verify this hypothesis, we have carried out an extensive study of the transport properties of LMO over a wide P-T region (12 < P < 54 GPa and 10 < T < 300 K) and applied magnetic field H, varying from 0 to 8 T. Here, we report the realization of CMR in a narrow pressure range between 3...

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Section: Significancementioning

confidence: 99%

Origin of colossal magnetoresistance in LaMnO ₃ manganite

Baldini

Muramatsu

Sherafati

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…The calculated density of electrons n versus chemical potential µ for a one-dimensional model has shown a clear discontinuity in n at a particular value of µ, indicating a PS [7,8] since in general electronic PS results in the pinning of µ. Indeed, electron microscopy studies have revealed inhomogeneous spatial images in which the FM charge-disordered and AFM CO microdomains coexist [9,10,11]. However, it has been unclear whether they are driven by (intrinsic) tendency toward electronic PS or triggered by (extrinsic) chemical inhomogenity.…”

Section: Introductionmentioning

confidence: 99%

Chemical potential shift and spectral-weight transfer inPr1−xCaxMnO3revealed by phot

et al. 2006

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We have studied the chemical potential shift and changes in the electronic density of states near the Fermi level (EF ) as a function of carrier concentration in Pr1−xCaxMnO3 (PCMO, 0.2 ≤ x ≤ 0.65) through the measurements of photoemission spectra. The results showed that the chemical potential shift was suppressed for x 0.3, where the charge exchange (CE)-type antiferromagnetic chargeordered state appears at low temperatures. We consider this observation to be related to charge self-organization such as stripe formation on a microscopic scale in this composition range. Together with the previous observation of monotonous chemical potential shift in La1−xSrxMnO3, we conclude that the tendency toward the charge self-organization increases with decreasing bandwidth. In the valence band, spectral weight of the Mn 3d eg electrons in PCMO was transferred from ∼ 1 eV below EF to the region near EF with hole doping, leading to a finite intensity at EF even in the paramagnetic insulating phase for x 0.3, probably related with the tendency toward charge selforganization. The finite intensity at EF in spite of the insulating transport behavior is consistent with fluctuations involving ferromagnetic metallic states.

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“…A possible interpretation of the result is that the mesoscopic FM region is itself inhomogeneous at the nanoscale with coexisting metallic and charge-ordered regions. A final example of mesoscale electronic inhomogeneities is from the experiments of Sarma et al (2004), who used photoemission spectromicroscopy which has the advantage of spatially resolving the local metallic/non-metallic nature and simultaneously determining the local chemical composition with a resolution of approximately 0.5 mm. Using this technique, they studied La 0.25 Pr 0.375 Ca 0.375 MnO 3 .…”

Section: (A ) Signatures Of Electronic Inhomogeneitiesmentioning

confidence: 99%

Electronic phase separation and other novel phenomena and properties exhibited by mixed-valent rare-earth manganites and related materials

Shenoy

Rao

2007

Phil. Trans. R. Soc. A.

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Transition metal oxides, such as the mixed-valent rare-earth manganites Ln (1Kx) A x MnO 3 (Ln, rare-earth ion, and A, alkaline-earth ion), show a variety of electronic orders with spatially correlated charge, spin and orbital arrangements, which in turn give rise to many fascinating phenomena and properties. These materials are also electronically inhomogeneous, i.e. they contain disjoint spatial regions with different electronic orders. Not only do we observe signatures of such electronic phase separation in a variety of properties, but we can also observe the different 'phases' visually through different types of imaging. We discuss various experiments pertaining to electronic orders and electronic inhomogeneities in the manganites and present a discussion of theoretical approaches to their understanding. It is noteworthy that the mixed-valent rare-earth cobaltates of the type Ln (1Kx) A x CoO 3 also exhibit electronic inhomogeneities just as the manganites.

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Direct Observation of Large Electronic Domains with Memory Effect in Doped Manganites

Cited by 91 publications

References 12 publications

Origin of colossal magnetoresistance in LaMnO ₃ manganite

Origin of colossal magnetoresistance in LaMnO ₃ manganite

Chemical potential shift and spectral-weight transfer inPr1−xCaxMnO3revealed by phot

Electronic phase separation and other novel phenomena and properties exhibited by mixed-valent rare-earth manganites and related materials

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Direct Observation of Large Electronic Domains with Memory Effect in Doped Manganites

Cited by 91 publications

References 12 publications

Origin of colossal magnetoresistance in LaMnO 3 manganite

Origin of colossal magnetoresistance in LaMnO 3 manganite

Chemical potential shift and spectral-weight transfer inPr1−xCaxMnO3revealed by phot

Electronic phase separation and other novel phenomena and properties exhibited by mixed-valent rare-earth manganites and related materials

Contact Info

Product

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Origin of colossal magnetoresistance in LaMnO ₃ manganite

Origin of colossal magnetoresistance in LaMnO ₃ manganite