Electronic and Magnetic Nano Phase Separation in Cobaltates La2−x Sr x CoO4

Li, Z. W.; Drees, Y.; Ricci, Alessandro; Lamago, D.; Piovano, Andrea; Rotter, Martin; Schmidt, W.; Sobolev, Oleg; Rütt, U.; Gutowski, Olof; Sprung, Michael; Castellan, J. P.; Tjeng, L. H.; Komarek, A. C.

doi:10.1007/s10948-015-3302-4

Cited by 11 publications

(8 citation statements)

References 34 publications

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“…In materials with regions of short-range atomic order that have different magnetic ground states, the neighboring domains can interact and cause a strong competition between magnetic states in a way that leads to complex magnetic behavior. 31 Such an effect was observed in TlFe 1.6 Se 2 , where a complete spin reorientation is observed in crystals with ordering of Fe vacancies but a competition for moment orientation is observed when nanoscale phase separation exists between atomically ordered and disordered regions. 32 Both Fe 5−x GeTe 2 and TlFe 1.6 Se 2 possess magnetoelastic coupling evidenced by a large lattice response across a magnetic transition, Table 2.…”

Section: B Evolution Of Magnetic Propertiesmentioning

confidence: 86%

Tuning Magnetic Order in the van der Waals Metal Fe5GeTe2 by Cobalt Substitution

May,

Du,

Cooper

et al. 2020

Preprint

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Fe5−xGeTe2 is a van der Waals (vdW) material with one of the highest reported bulk Curie temperatures, TC ≈310 K. In this study, theoretical calculations and experiments are utilized to demonstrate that the magnetic ground state is highly sensitive to local atomic arrangements and the interlayer stacking. Cobalt substitution is found to be an effective way to manipulate the magnetic properties while also increasing the ordering temperature. In particular, cobalt substitution up to 30% enhances TC and changes the magnetic anisotropy, while ≈50% cobalt substitution yields an antiferromagnetic state. Single crystal x-ray diffraction evidences a structural change upon increasing the cobalt concentration, with a rhombohedral cell observed in the parent material and a primitive cell observed for ≈46% cobalt content. First principles calculations demonstrate that it is a combination of high cobalt content and the concomitant change to primitive layer stacking that produces antiferromagnetic order. These results illustrate the sensitivity of magnetism in Fe5−xGeTe2 to composition and structure, and emphasize the important role of structural order/disorder and layer stacking in cleavable magnetic materials.

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Section: B Evolution Of Magnetic Propertiesmentioning

confidence: 86%

Tuning Magnetic Order in the van der Waals Metal Fe5GeTe2 by Cobalt Substitution

May,

Du,

Cooper

et al. 2020

Preprint

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“…Indeed, there are similarities between the upper part of the hour-glass magnetic spectrum in La 2−x Sr x CoO 4 and the spectrum in undoped La 2 CoO 4 [21] and also similarities of the lower part of the hour-glass spectrum and half-doped La 1.5 Sr 0.5 CoO 4 [22]. The major difference to conventional phase separation is that the outwards-dispersing branches of the low-energy magnetic excitations are missing (and that energies are renormalized to some extent), i.e., nano phase separation is different from conventional phase separation where the observation of a simple superposition of the magnetic excitation spectra of undoped and half-doped phases would be expected-without any suppression of the outwards-dispersing branches of the low-energy excitations (and without a renormalization of energies) [23].…”

Section: Introductionmentioning

confidence: 94%

Suppression of the outwards-dispersing branches in hour-glass magnetic spectra induced by nanoscale phase separation in La2−xSrxCoO4

Guo

Sakong

et al. 2019

Phys. Rev. B

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Here, we reinvestigate the underlying charge and magnetic correlations in La 2−x Sr x CoO 4 within a combined study of muon spin relaxation (μSR), x-ray photon correlation spectroscopy, synchrotron radiation singlecrystal x-ray diffraction, and neutron-scattering measurements. For La 2−x Sr x CoO 4 around 1/3 hole-doping, the significant charge correlations that are responsible for the emergence of hour-glass magnetic spectra are found to be slowly fluctuating checkerboard charge ordering (CBCO) correlations with an onset temperature being independent of hole-doping. This reveals a local origin of the CBCO correlations in the rather ionic cobaltates, thus being distinct from the more covalent nickelates. Moreover, we report the observation of a very similar temperature dependence of the intensities of in-plane high-and low-energy excitations within the La 2−x Sr x CoO 4 hour-glass spectrum. This observation shows that nano phase separation is distinct from conventional phase separation and that there is a coupling between nanometer-sized undoped and hole-doped islands. Based on this, it is possible to propose a microscopic scenario for the suppression of the outwards-dispersing branches in hour-glass magnetic spectra.

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“…Besides of a comparative study of Sr 2 RhO 4 single crystals isotypic with Sr 2 RuO 4 mainly polycrystalline Sr 2−x La x RhO 4 samples were studied over a wider doping range x = 0 ∼ 1.0 [9][10][11] . Regarding the recent observations of charge order and nano phase separation in the 3d cobaltate system La 2−x Sr x CoO 4 [12][13][14][15] also the availability of single crystals of the 4d Rhodium analogue with hole-doping levels away from the end member Sr 2 RhO 4 and, especially, around 50% electron doping (Sr 1.5 La 0.5 RhO 4 ), would be of interest for future studies of the charge correlations.…”

Section: Introductionmentioning

confidence: 99%

Single-crystal growth and physical properties of 50% electron-doped rhodate Sr1.5La0.5RhO4

Guo

et al. 2017

Phys. Rev. Materials

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Centimeter-sized single crystals of Sr 1.5 La 0.5 RhO 4 were grown by the floating zone method at oxygen pressures of 20 bar. The quality of our single crystals was confirmed by X-ray Laue, powder and single crystal X-ray diffraction, neutron and X-ray absorbtion spectroscopy measurements. At ∼50% electron doping we observe RhO 3 octahedral rotations of ∼8.2• within the octahedral basal plane which are incompatible with space group I4/mmm. Our single crystal was further characterized by susceptibility, electrical transport and, finally, specific heat measurements showing a temperature dependent Debye temperature.

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Electronic and Magnetic Nano Phase Separation in Cobaltates La2−x Sr x CoO4

Cited by 11 publications

References 34 publications

Tuning Magnetic Order in the van der Waals Metal Fe5GeTe2 by Cobalt Substitution

Tuning Magnetic Order in the van der Waals Metal Fe5GeTe2 by Cobalt Substitution

Suppression of the outwards-dispersing branches in hour-glass magnetic spectra induced by nanoscale phase separation in La2−xSrxCoO4

Single-crystal growth and physical properties of 50% electron-doped rhodate Sr1.5La0.5RhO4

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