Finite-size shift of the Curie temperature of ferromagnetic lanthanum cobaltite thin films

Fuchs, D.; Schwarz, Thorsten; Morán, O.; Schweiß, P.; Schneider, R.

doi:10.1103/physrevb.71.092406

Cited by 42 publications

(32 citation statements)

References 30 publications

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“…This intercluster magnetotransport effect thus provides a simple probe of the existence of nanoscopic MEPS, a fact which played a key role in our recent study [13] of the degradation in magnetization and conductivity in SrTiO 3 (001)/La 1-x Sr x CoO 3 films [27,28]. This system was found to enter a suppressed magnetization state below a thickness, t*, of about 80 Å at x = 0.5, coincident with a crossover from metallic-like to insulating-like transport.…”

mentioning

confidence: 91%

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr
Sharma
¹
,
Gàzquez
²
,
Varela
³

et al. 2011
Phys. Rev. B

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Thin film perovskite cobaltites have been found to exhibit coercivity values enhanced by almost two orders of magnitude in comparison to bulk. In this work we have investigated this unexplained coercivity enhancement in detail, focusing on epitaxial which is responsible for the degradation in magnetic and electronic properties in the very thin film limit. The coercivity is shown to be intimately related to the existence of this (70Å thick) interfacial phase separated layer, leading us to advance an explanation for the coercivity enhancement in terms of pinning of domain walls by interfacial nanoscopic 2 ferromagnetic clusters, and a crossover to single domain clusters at very low thickness.Simple estimates of the magnetocrystalline anisotropy (from the maximum coercivity), cluster dimensions (from the superparamagnetic blocking temperature), multi domain to single domain crossover point, and domain wall width, provide quantitative support for this picture.

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mentioning

confidence: 91%

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr
Sharma
¹
,
Gàzquez
²
,
Varela
³

et al. 2011
Phys. Rev. B

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“…[10] However, the finite size and strain effects are intrinsic to the film, and it is not trivial to separate the influence of these two effects on a particular film. Recently, Fuchs et al [11] and Andres et al [12] have reported the finite thickness effect for the perovskite oxide films, La 0.7 Sr 0.3 CoO 3 and La 0.7 Ca 0.3 MnO 3 , respectively. However, the possible effects of strain were discounted in the analysis.…”

mentioning

confidence: 99%

Separation of the strain and finite size effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films

Xie

Budnick

Wells

et al. 2007

Applied Physics Letters

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The ferromagnetic properties of epitaxial La0.5Sr0.5CoO3 thin films have been studied. The magnetic transition is affected by both strain and finite thickness. We have used a series of films of different thickness and on different substrates in order to quantitatively determine the change in Curie temperature contributed by each effect. The phase diagram of TC versus in-plane strain suggests that the ferromagnetic transition temperature is suppressed by tensile strain and enhanced by compressive strain. The general method of separating strain and finite thickness effects should be applicable to any ordering phase transition in thin films.Thin films of perovskite oxide materials have attracted great attention lately due to their potential technological applications based on a variety of appealing physical properties, such as colossal magnetoresistivity, ferroelectricity, and high-Tc superconductivity. The properties of films differ from the corresponding bulk typically due to a combination of three factors. Firstly, defect levels are often higher in films. Oxygen deficiency is the most common defect and will typically suppress the transition temperature due to the decrease of doped hole density or the destruction of metal-oxygen hopping pathways.[1] Secondly, finite size effects may be important. For example, the Curie temperature (T C ) for a ferromagnetic thin film will be reduced when the spin-spin correlation length exceeds the film thickness. The thickness-dependent Curie temperature has been most carefully studied in simple metallic films of Fe, Co, Ni and Gd. [2, 3] A similar scaling effect has also been found in ferroelectric materials. [4] Thirdly, strain incorporated into films due to effects such as a lattice mismatch with the substrate may also alter the phase transition through changes in fundamental interactions that depend upon atomic spacing. Strain in thin films is often thought of as analogous to that induced in high-pressure experiments on bulk materials. However, a much larger strain can be achieved in films than that in bulk and the strain in films is usually biaxial rather than hydrostatic or uniaxial as in most bulk pressure experiments. The induced strain can modify the lattice structure, the critical temperature for phase transition, and sometimes the nature of the phases present themselves. [5,6,7] La 0.5 Sr 0.5 CoO 3 (LSCO) is a highly doped ferromagnetic oxide material with perovskite structure and has desirable properties of high electrical conductivity and large magnetoresistance. [8,9] Thin film LSCO is a candidate for applications such as electrodes for fuel cells, ferroelectric memory and spin valve devices. The first concern noted above, the oxygen content in LSCO films, can be controlled by carefully optimizing growth conditions so that stoichiometry of oxygen can be maintained. [10] However, the finite size and strain effects are intrinsic to the film, and it is not trivial to separate the influence of these two effects on a particular film. Recently, Fuchs et al [11] and Andre...

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“…The best fits for the resistivity data were found for the VRH model (130 K < T < 18 K) as well as for the Efros-Shklovskii model (310 K < T < 149 K). VRH takes place in disordered systems where charge carriers move by hopping between localized electronic states and its validity is evidenced on cobaltites [6,8,9]. One can note (see inset of Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Such a difference could be ascribed to (i) significantly compressed ab plane and tensile strained lattice along the c-axis, and (ii) appearance of a shear stress in layer regions located far from the substrate surface, due to lattice relaxation (like in Ref. [9]). In order to elucidate the conduction mechanism we have fit to ρ vs. T data (see Table) the generalized formula for activated hopping model, where ρ is given by ρ = exp(T 0 /T ) 1/n .…”

Section: Resultsmentioning

confidence: 99%

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Structural, Magnetic and Transport Properties οf NdBaCo₂O_5+xThin Films Deposited by Magnetron Sputtering

et al. 2009

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For the first time, thin films of NdBaCo2O5+x were deposited by RF magnetron sputtering on different substrates. The films deposited on SrLaAlO4(001) substrates exhibited highly textured structure with c-axis directed out-of-plane. Magnetic measurements M vs. T of three NdBaCo2O5+x/SrLaAlO4(001) films revealed successively paramagnetic-ferromagnetic-antiferromagnetic transitions with decrease in temperature. Their paramagnetic Curie-Weiss temperatures were estimated to be in the range of TC = 100-116 K. Resistivity of the cobaltite thin film exhibited insulating behavior and the best fit was found for the variable range hopping mechanism.

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Finite-size shift of the Curie temperature of ferromagnetic lanthanum cobaltite thin films

Cited by 42 publications

References 30 publications

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr
Sharma
¹
,
Gàzquez
²
,
Varela
³

et al. 2011
Phys. Rev. B

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr
Sharma
¹
,
Gàzquez
²
,
Varela
³

et al. 2011
Phys. Rev. B

Separation of the strain and finite size effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films

Structural, Magnetic and Transport Properties οf NdBaCo₂O_5+xThin Films Deposited by Magnetron Sputtering

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Finite-size shift of the Curie temperature of ferromagnetic lanthanum cobaltite thin films

Cited by 42 publications

References 30 publications

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5SrSharma1, Gàzquez2, Varela3 et al. 2011Phys. Rev. B

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5SrSharma1, Gàzquez2, Varela3 et al. 2011Phys. Rev. B

Separation of the strain and finite size effect on the ferromagnetic properties of La0.5Sr0.5CoO3 thin films

Structural, Magnetic and Transport Properties οf NdBaCo2O5+xThin Films Deposited by Magnetron Sputtering

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Product

Resources

About

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr
Sharma
¹
,
Gàzquez
²
,
Varela
³

et al. 2011
Phys. Rev. B

Coercivity enhancement driven by interfacial magnetic phase separation in SrTiO3(001)/Nd0.5Sr
Sharma
¹
,
Gàzquez
²
,
Varela
³

et al. 2011
Phys. Rev. B

Structural, Magnetic and Transport Properties οf NdBaCo₂O_5+xThin Films Deposited by Magnetron Sputtering