Limited local electron-lattice coupling in manganites: An electron diffraction study

Sánchez, D. R.; Calderón, M. J.; Sánchez-Benítez, Javier; Williams, A. J.; Attfield, J. Paul; Midgley, Paul A.; Mathur, N. D.

doi:10.1103/physrevb.77.092411

Cited by 9 publications

(11 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Equation ( 4) has the same form as derived from consideration of Jahn-Teller theory, and softening of the shear modulus above T co has been used to estimate a value of T * c − T c = 2 K for La 0.5 Ca 0.5 MnO 3 [27]. The strain evolution and elastic properties obtained by RUS for the incommensurate structure of La 0.5 Ca 0.5 MnO 3 are similar in form to those previously obtained for Pr 0.48 Ca 0.52 MnO 3 , which has a nearly identical incommensurate structure stable below ∼235 K [65][66][67]. Comparison of figure 7 of Carpenter et al [50] with figure 2 of the present work shows that values of |e tx | for bulk samples increase by ∼0.025 through T co , and |e 4 | changes by ∼0.003 in both cases.…”

Section: Strain/order Parameter Couplingsupporting

confidence: 64%

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La_0.5Ca_0.5MnO₃

Pagliari

Dapiaggi

Maglia

et al. 2014

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Elastic and anelastic properties of La0.5Ca0.5MnO3 determined by resonant ultrasound spectroscopy in the frequency range ∼100-1200 kHz have been used to evaluate the role of grain size in determining the competition between ferromagnetism and Jahn-Teller/charge order of manganites which show colossal magneto resistance. At crystallite sizes of ∼75 and ∼135 nm the dominant feature is softening of the shear modulus as the charge order transition point, Tco (∼225 K), is approached from above and below, matching the form of softening seen previously in samples with 'bulk' properties. This is consistent with a bilinear dominant strain/order parameter coupling, which occurs between the tetragonal shear strain and the Jahn-Teller (Γ3(+)) order parameter. At crystallite sizes of ∼34 and ∼42 nm the charge ordered phase is suppressed but there is still softening of the shear modulus, with a minimum near Tco. This indicates that some degree of pseudoproper ferroelastic behaviour is retained. The primary cause of the suppresion of the charge ordered structure in nanocrystalline samples is therefore considered to be due to suppression of macroscopic strain, even though MnO6 octahedra must develop some Jahn-Teller distortions on a local length scale. This mechanism for stabilizing ferromagnetism differs from imposition of either an external magnetic field or a homogeneous external strain field (from a substrate), and is likely to lead both to local strain heterogeneity within the nanocrystallites and to different tilting of octahedra within the orthorhombic structure. An additional first order transition occurs near 40 K in all samples and appears to involve some very small strain contrast between two ferromagnetic structures.

show abstract

Section: Strain/order Parameter Couplingsupporting

confidence: 64%

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La_0.5Ca_0.5MnO₃

Pagliari

Dapiaggi

Maglia

et al. 2014

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…However, it is possible that  = 0 locally, as q/a* = 0.480(2) at 20 K [Fig. 1(e)] matches within error the expected low-temperature value of (1-x) = 0.48, unlike bulk 11 Pr 0.48 Ca 0.52 MnO 3 where   0 and q/a*  0.46.…”

supporting

confidence: 60%

“…In summary, we have used TEM to show that an untwinned (001)-oriented film of Pr 0.48 Ca 0.52 MnO 3 shows superlattice modulations along a. Unlike bulk manganites of this composition 11 , the superlattice is aligned with the parent lattice ( = 0) on a length scale of 100 nm or less. We suggest that this is due to epitaxial strain overcoming a relatively weak 11 local electron-lattice coupling.…”

mentioning

confidence: 98%

See 1 more Smart Citation

The absence of charge-density-wave sliding in epitaxial charge-ordered Pr_0.48Ca_0.52MnO₃films

Fisher¹,

Genossar²,

Patlagan³

et al. 2010

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

For an epitaxial Pr 0.48 Ca 0.52 MnO 3 film on NdGaO 3 , we use transmission electron microscopy to observe a "charge-ordered" superlattice along the in-plane direction a. The same film shows no electrical signatures of charge order. The in-plane electrical anisotropy  a / c = 28 is constant, and there is no evidence of sliding charge density waves up to the large field of ~10 3 V/cm. Perovskite manganites 1 of the form (RE 3+ ,AE 2+ )MnO 3 (RE = rare earth, AE = alkaline earth) show two predominant low-temperature phases, namely the ferromagnetic metal which is highly spin polarized, and the so-called "chargeordered" (CO) insulator in which a superlattice is experimentally observed. The CO phase was originally described in terms of Mn 3+/ Mn 4+ ordering 2-5 , but widespread doubt about this interpretation has arisen 6-10 . It is now accepted that this picture is inaccurate, especially given that the superlattice is slightly misoriented and locally incommensurate for 10 La 0.48 Ca 0.52 MnO 3 and 11 Pr 0.48 Ca 0.52 MnO 3 . Complete charge disproportionation is coulombically expensive and a charge density wave (CDW) picture has been proposed [12][13][14][15][16][17]10 . It is therefore interesting to investigate whether it is possible to observe CDW sliding.Recently it was argued 18 that epitaxial La 0.5 Ca 0.5 MnO 3 films on NdGaO 3 (001) show CDW sliding in fields of ~10 2 V/cm, but the measurement geometry was irregular and so inhomogeneous heating currents cannot be ruled out 19 . These measurements are difficult to replicate, as La 0.5 Ca 0.5 MnO 3 superlattice reflections in transmission electron microscopy (TEM) diffraction patterns are normally absent 20 , and if present they are weak 18,21 . Strong signatures of CO have been observed in (011)-oriented films of 22,23 Nd 0.5 Sr 0.5 MnO 3 and 24 Bi 0.4 Ca 0.6 MnO 3 , but this orientation promotes both a rough surface and also defects that would pin CDWs. Here we investigate an (001)-oriented epitaxial Pr 0.48 Ca 0.52 MnO 3 film in which we observe distinct superlattice reflections. The electrical resistivity shows no sign of the CO transition at

show abstract

“…Recently, nonmonotonic temperature dependent H EB has been observed in various exchange-biased systems. − Jammalamadaka et al explained oscillations in the temperature dependence of H EB ( T ) in 10 nm Pr 0.5 Ca 0.5 MnO 3 NPs by propagation of the incommensurate charge density wave (ICDW) with a strongly temperature dependent wavelength in the AFM core. Such an origin of the oscillatory exchange bias has been originally suggested for FM/AFM layers. , An incommensurate charge density wave scenario was also evoked − for some typical charge-ordered polycrystalline manganites in which an AFM/CO phase coexists with the FM phase. Even in principle feasible, the possibility of low energy excitations in the form of ICDW in AFM CO manganite films and NPs has been recently questioned. , Fisher et al have studied electrical resistivity in an (001)-oriented epitaxial Pr 0.48 Ca 0.52 MnO 3 film with distinct superlattice reflections associated with CO.…”

Section: Resultsmentioning

confidence: 79%

Particle Size Effects on Charge Ordering and Exchange Bias in Nanosized Sm_0.43Ca_0.57MnO₃

Markovich

Puźniak

Fita³

et al. 2014

J. Phys. Chem. C

View full text Add to dashboard Cite

Size dependence of magnetic properties of Sm0.43Ca0.57MnO3 nanoparticles with average size of 15–60 nm has been investigated. Charge ordering, characteristic for the bulk form of this material, was found to be gradually suppressed with decreasing particle size and fully disappearing in 15 nm nanoparticles. Onsets of ferromagnetic contributions to the magnetization appear below 90 K, independently on the particle size, while spontaneous magnetization at 10 K increases with decreasing particle size. Magnetic hysteresis loops exhibit size dependent exchange bias effect manifested by horizontal H EB and vertical M EB shifts, appearing after field cooling. Variation of H EB and M EB shows opposite size dependences; H EB decreases while M EB increases with decreasing particle size. For large 60 nm particles, H EB decreases monotonously with increasing temperature, while for the smallest 15 nm particles it shows surprising nonmonotonic temperature dependence. Size and temperature dependences are discussed in terms of magnetic coupling between antiferromagnetic cores and shells containing ferromagnetic clusters in a frustrated spin configuration.

show abstract

Limited local electron-lattice coupling in manganites: An electron diffraction study

Cited by 9 publications

References 33 publications

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La_0.5Ca_0.5MnO₃

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La_0.5Ca_0.5MnO₃

The absence of charge-density-wave sliding in epitaxial charge-ordered Pr_0.48Ca_0.52MnO₃films

Particle Size Effects on Charge Ordering and Exchange Bias in Nanosized Sm_0.43Ca_0.57MnO₃

Contact Info

Product

Resources

About

Limited local electron-lattice coupling in manganites: An electron diffraction study

Cited by 9 publications

References 33 publications

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La0.5Ca0.5MnO3

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La0.5Ca0.5MnO3

The absence of charge-density-wave sliding in epitaxial charge-ordered Pr0.48Ca0.52MnO3films

Particle Size Effects on Charge Ordering and Exchange Bias in Nanosized Sm0.43Ca0.57MnO3

Contact Info

Product

Resources

About

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La_0.5Ca_0.5MnO₃

Strain heterogeneity and magnetoelastic behaviour of nanocrystalline half-doped La, Ca manganite, La_0.5Ca_0.5MnO₃

The absence of charge-density-wave sliding in epitaxial charge-ordered Pr_0.48Ca_0.52MnO₃films

Particle Size Effects on Charge Ordering and Exchange Bias in Nanosized Sm_0.43Ca_0.57MnO₃