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Temperature-dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La1-xSrxMnO3

Temperature-dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La1-xSrxMnO3
chair:

Mannella, N. / Booth, C. / Rosenhahn, A. / Sell, B. / Nambu, A. / Marchesini, S. / Mun, B. / Yang, S. / Watanabe, M. / Ibrahim, K. / Arenholz, E. / Young, A. / Guo, J. / Tomioka, Y. / Fadley, C. (2008)

place:

Physical Review B 77 (2008), 12, 125134   

Date: 2008

Mannella, N. / Booth, C. / Rosenhahn, A. / Sell, B. / Nambu, A. / Marchesini, S. / Mun, B. / Yang, S. / Watanabe, M. / Ibrahim, K. / Arenholz, E. / Young, A. / Guo, J. / Tomioka, Y. / Fadley, C. (2008):  „Temperature-dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La1-xSrxMnO3“. In: Physical Review B 77 (2008), 12, 125134  

Abstract

We have studied the temperature-dependent evolution of the electronic and local atomic structure in the cubic colossal magnetoresistive manganite La(1-x)Sr(x)MnO(3) (x = 0.3-0.4) with core and valence level photoemission (PE), x-ray absorption spectroscopy (XAS), x-ray emission spectroscopy (XES), resonant inelastic x-ray scattering (RIXS), extended x-ray absorption fine structure (EXAFS) spectroscopy, and magnetometry. As the temperature is varied across the Curie temperature T(C), our PE experiments reveal a dramatic change of the electronic structure involving an increase in the Mn spin moment from approximate to 3 mu(B) to approximate to 4 mu(B), and a modification of the local chemical environment of the other constituent atoms, indicative of electron localization on the Mn atom.

These effects are reversible and exhibit a slow-time scale, with an approximate to 200-K-wide hysteresis centered at T(C). Based on the probing depths accessed in our PE measurements, these effects seem to survive for at least 35-50 angstrom inward from the surface, while other consistent signatures for this modification of the electronic structure are revealed by more bulk-sensitive spectroscopies such as XAS and XES/RIXS. We interpret these effects as spectroscopic fingerprints for polaron formation, associated with the presence of local Jahn-Teller distortions of the MnO(6) octahedra around the Mn atom, as revealed by the EXAFS data. Magnetic susceptibility measurements, in addition, show typical signatures of ferromagnetic-cluster formation well above the Curie temperature.