ELECTRONIC BAND STRUCTURE OF La

ISSRNS 2012: Abstracts / Synchrotron Radiation in Natural Science Vol. 11, No 1 – 2 (2012) P 66

ELECTRONIC BAND STRUCTURE OF La

Pb

Mn

Fe

O

W. Tokarz^1∗, M. Kowalik^1,2, R. Zalecki¹, and A. Ko lodziejczyk¹

1AGH University of Science and Technology, Department of Solid State Physics, 30, Mickiewicza Str., 30–059 Cracow, Poland

2Department of Physics, Rzesz´ow University of Technology, 6, Powsta´nc´ow Warszawy Str., 35–959 Rzesz´ow, Poland

Keywords: density of states, density functional theory, perovskite, ultraviolet photoemission

∗e-mail : tokarz@agh.edu.pl

We present theoretical study of some electric and magnetic properties in manganese perovskite La_0.67Pb_0.33Mn_0.92Fe_0.08O₃. The calculation was carried out based on first-principles density func- tional theory (DFT) with general gradient approxi- mation GGA+U using Wien2K package. The P-3c1 crystal structure was taken from the detailed X-ray diffraction data for the perovskite [1]. The original unit cell was multiplied two times in all direction in order to place proper amount of Fe. Final crystal structure with 120 atoms was used for calculation.

According to our previous work [2], where it was shown that antiparallel magnetic moment configu- ration on Mn and Fe gives more reasonable results than parallel one, spins up and down for Mn and Fe were set up as initial parameters, respectively.

For Mn and Fe d electrons the exact exchange en- ergy was utilized. As a results half-metallic density of state (DOS) was obtained with top of valance band for spin down 1.5 eV below E_F and spin up filled up to Fermi level by Mn, Fe d and oxygen p electrons. In the valance band oxygen partial DOS follows sum of Mn and Fe ones. It is shown in Fig. 1 as an example. Comparison of total DOS with

ultraviolet photoemission spectroscopy (UPS) mea- surements shows similar features [2] up to −10 eV and especially the decrease in DOS from −2 eV to E_F. Computed total magnetic moment was overes- timated as compared to measured one.

Acknowledgments: This work was supported by the Polish Ministry of Science and Higher Education and its grants for Scientific Research.

References

[1] G. Gritzner, M. Koppe, K. Kellner, J. Przewoznik, J. Chmist, A. Ko lodziejczyk, K. Krop, “Preparation and properties of La0.67Pb0.33(Mn1−xFex)O3 com- pounds,” Appl. Phys. A 81 (2005) 1491 – 1495.

[2] M. Kowalik, R. Zalecki, A. Ko lodziejczyk, “Elec- tronic states of collosal magnetoresistive manganites La0.67Pb0.33Mn1−xFexO3 from photoemission spec- troscopy,” Acta Phys. Pol. A 117 (2010) 257 – 260.

Figure 1 : Partial DOS of manganese, iron and oxygen.

151