Electrical Transport in the Ferromagnetic State of Manganites: Small-Polaron Metallic Conduction at Low Temperatures

Zhao, Guangyao; Smolyaninova, Vera N.; Prellier, W.; Keller, H.

doi:10.1103/physrevlett.84.6086

Cited by 145 publications

(134 citation statements)

References 40 publications

(33 reference statements)

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“…The values of the fitting parameterhω s /2k B of the La 0.8−y Sr 0.2 MnO 3 films are in the 15.1 to 71.9 K range, in agreement with values determined from lowtemperature specific heat (hω s /2k B = 48 K) and other resistivity studies of La 1−x Ca x MnO 3 [13,17]. In addition, inelastic neutron scattering [25] and reflectivity [26] measurements support the phononic character of charge carriers for La 0.8 Sr 0.2 MnO 3 .…”

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Spin-wave scattering at low temperatures in manganite films

et al. 2003

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The temperature T and magnetic field H dependence of the resistivity ρ has been measured for La0.8−ySr0.2MnO3 (y=0 and 0.128) films grown on (100) SrTiO3 substrates. The low-temperature ρ in the ferromagnetic metallic region follows well ρ(H, T ) = ρ0(H) + A(H)ωs/ sinh(hωs/2kBT ) + B(H)T 7/2 with ρ0 being the residual resistivity. We attribute the second and third term to smallpolaron and spin-wave scattering, respectively. Our analysis based on these scattering mechanisms also gives the observed difference between the metal-insulator transition temperatures of the films studied. Transport measurements in applied magnetic field further indicate that spin-wave scattering is a key transport mechanism at low temperatures. The observation of colossal magnetoresistance CMR effect in manganite films [1] has produced a resurgence of interest in these materials for both fundamental physics and their possible application in recording media and magnetic switching devices. The microscopic transport mechanism in these materials has long been thought to be double exchange DE [2,3,4]. However, it has been realized [5] that the effective carrier-spin interaction in the DE model is too weak to lead to a significant reduction of the electronic bandwidth, which would justify the observed several orders of magnitude increase in conductivity just below the Curie temperature T C . Indeed, a large number of experiments have shown that the DE scenario alone cannot account for the properties of the manganites and that CMR is not purely electronic in origin [6,7].Low-temperature charge transport measurements of manganites in the ferromagnetic metallic state are essential in clarifying the specific mechanisms responsible for the CMR effect. At low temperatures, a dominant T 2 term in resistivity has generally been observed [8,9,10]. Although the T 2 behavior is consistent with electronelectron interaction [11], the coefficient of the T 2 term is about 60 to 70 times larger than the one expected for electron-electron scattering [12]. Moreover, a careful check of the low-temperature resistivity [13,14] has shown substantial deviation from the T 2 −like behavior in the very low temperature region. Other power-law temperature dependences of the resistivity have also been reported [10,14,15,16,17,18,19]. At present, there is no agreement on the actual scattering mechanism below the Curie temperature.Here, we address the low-temperature scattering mechanism in manganites through resistivity measurements of La 0.8−y Sr 0.2 MnO 3 (y = 0 and 0.128) films grown on SrTiO 3 substrates, measured in zero field as well as applied magnetic fields up to 14 T. Our data indicate that spin-wave scattering, which gives a T 7/2 dependence in the low-temperature resistivity, is a dominant dissipation mechanism in the ferromagnetic state of these manganites, besides scattering of small polarons by a soft optical phonon mode. Our analysis of the resistivity data in terms of small-polaron and spin-wave scattering mechanisms, and the spin fluctuation model also g...

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confidence: 71%

“…According to the theory of small-polaron conduction at low temperatures [24], the relaxation rate 1/τ for small polarons is proportional to 1/ sinh 2 (hω s /2k B T ) [ 13,17]. Thus, the term Aω s / sinh 2 (hω s /2k B T ) in Eq.…”

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confidence: 99%

Spin-wave scattering at low temperatures in manganite films

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“…However, low-temperature resistivity measurements of epitaxial thin films of La 1−x Ca x MnO 3 provide support for the presence of small-polaron conduction in the ferromagnetic (FM) state. 5,6 In the same system, a T 9/2 term attributed to electron-magnon scattering was also found in the T dependence of resistivity at lowtemperatures. 1,6 Therefore, the low-temperature electrical transport mechanism of manganites remains controversial and is far from being fully understood.…”

Section: Introductionmentioning

confidence: 69%

“…1,2,3,4,5,6 Recent studies on single crystals of the three-dimensional 3D pseudocubic compounds R 1−x A x MnO 3 (R is a trivalent rare-earth ion and A is a divalent alkaline-earth ion) show a T 2 dependence of the resistivity, 2,3,4 which has been interpreted as either electron-electron 3,4 or one-magnon 2 scattering. However, low-temperature resistivity measurements of epitaxial thin films of La 1−x Ca x MnO 3 provide support for the presence of small-polaron conduction in the ferromagnetic (FM) state.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature electrical transport in bilayer manganiteLa1.2Sr1.8Mn<

et al. 2002

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The temperature T and magnetic field H dependence of anisotropic in-plane ρ ab and out-of-plane ρc resistivities have been investigated in single crystals of the bilayer manganite La1.2Sr1.8Mn2O7. Below the Curie transition temperature Tc = 125 K, ρ ab and ρc display almost the same temperature dependence with an up-turn around 50 K. In the metallic regime (50 K ≤ T ≤ 110 K), both ρ ab (T ) and ρc(T ) follow a T 9/2 dependence, consistent with the two-magnon scattering. We found that the value of the proportionality coefficient B f it ab and the ratio of the exchange interaction J ab /Jc obtained by fitting the data are in excellent agreement with the calculated B ab based on the twomagnon model and J ab /Jc deduced from neutron scattering, respectively. This provides further support for this scattering mechanism. At even lower T , in the non-metallic regime (T < 50 K), both the in-plane σ ab and out-of-plane σc conductivities obey a T 1/2 dependence, consistent with weak localization effects. Hence, this demonstrates the three-dimensional metallic nature of the bilayer manganite La1.2Sr1.8Mn2O7 at T < Tc.

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“…Amongst them are mechanisms based on spin-polarized tunnelling via grain boundaries, 16 Kondo-like effects ( magnetic-and charge-type), [17][18][19] and quantum interference effects (QIE) arising from electron-electron interactions and weak localization, 1,12 just to name a few. However, a clear picture has not yet emerged and is still under discussion 9,20 impeding our understanding of the physics of correlated electron systems. Reviewing these existing explanations, the question whether or not the scattering related minimum at low temperature is a spin dependent effect emerged as a key issue in its understanding.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic and precipitate-induced quantum corrections to conductivity in La2/3Sr1/3MnO
Gao
¹
,
Cao
²
,
Zhang
³

et al. 2012
Phys. Rev. B

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Electrical Transport in the Ferromagnetic State of Manganites: Small-Polaron Metallic Conduction at Low Temperatures

Cited by 145 publications

References 40 publications

Spin-wave scattering at low temperatures in manganite films

Spin-wave scattering at low temperatures in manganite films

Low-temperature electrical transport in bilayer manganiteLa1.2Sr1.8Mn<

Intrinsic and precipitate-induced quantum corrections to conductivity in La2/3Sr1/3MnO
Gao
¹
,
Cao
²
,
Zhang
³

et al. 2012
Phys. Rev. B

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Electrical Transport in the Ferromagnetic State of Manganites: Small-Polaron Metallic Conduction at Low Temperatures

Cited by 145 publications

References 40 publications

Spin-wave scattering at low temperatures in manganite films

Spin-wave scattering at low temperatures in manganite films

Low-temperature electrical transport in bilayer manganiteLa1.2Sr1.8Mn<

Intrinsic and precipitate-induced quantum corrections to conductivity in La2/3Sr1/3MnOGao1, Cao2, Zhang3 et al. 2012Phys. Rev. B

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Intrinsic and precipitate-induced quantum corrections to conductivity in La2/3Sr1/3MnO
Gao
¹
,
Cao
²
,
Zhang
³

et al. 2012
Phys. Rev. B