Antiferromagnetic fluctuations and charge carrier localization in ferromagnetic bilayer manganites: electrical resistivity scales exponentially with short-range order controlled by temperature and magnetic field.
J Phys Condens Matter
; 32(37): 374013, 2020 Apr 14.
Article
en En
| MEDLINE
| ID: mdl-32289761
The compound La2-2x Sr1+2x Mn2O7, x = 0.30-0.40, consists of bilayers of ferromagnetic metallic MnO2 sheets that are separated by insulating layers. The materials show colossal magnetoresistance-a reduction in resistivity of up to two orders of magnitude in a field of 7 T-at their three-dimensional ordering temperatures, T C = 90-126 K, and are the layered analogues of the widely studied pseudo-cubic perovskite manganites, R1-x A x MnO3 (R = rare earth, A = Ca, Sr, Ba, Pb). Two distinct short-range orderings-antiferromagnetic fluctuations and correlated polarons, which are related to the magnetic and the lattice degrees of freedom respectively-have previously been discovered in La2-2x Sr1+2x Mn2O7, x = 0.40, and have each been qualitatively connected to the resistivity. Here, in a comprehensive study as a function of both temperature and magnetic field for the different hole-concentrations per Mn site of x = 0.30 and 0.35, we show that antiferromagnetic fluctuations also appear at temperatures just above T C, and that the intensities of both the antiferromagnetic fluctuations and polaron correlations closely track the resistivity. In particular, for x = 0.35 we show that there is a simple scaling relation between the intensities of the antiferromagnetic fluctuations and the in-plane resistivity that applies for the temperatures and magnetic fields used in the experiments. The results show that antiferromagnetic fluctuations are a common feature of La2-2x Sr1+2x Mn2O7 with ferromagnetic bilayers, and that there is a close connection between the antiferromagnetic fluctuations and polarons in these materials.
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01-internacional
Base de datos:
MEDLINE
Idioma:
En
Revista:
J Phys Condens Matter
Asunto de la revista:
BIOFISICA
Año:
2020
Tipo del documento:
Article
País de afiliación:
Reino Unido
Pais de publicación:
Reino Unido