Photoemission and x-ray absorption spectroscopy study of electron-doped colossal magnetoresistive manganiteLa0.7Ce0.3

Abstract

The electronic structure of La0.7Ce0.3MnO3 (LCeMO) thin film has been investigated using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS). The Ce 3d core-level PES and XAS spectra of LCeMO are very similar to those of CeO2, indicating that Ce ions are far from being trivalent. A very weak 4f resonance is observed around the Ce 4d → 4f absorption edge, suggesting that the localized Ce 4f states are almost empty in the ground state. The Mn 2p XAS spectrum reveals the existence of the Mn 2+ multiplet feature, confirming the Mn 2+ -Mn 3+ mixedvalent states of Mn ions in LCeMO. The measured Mn 3d PES/XAS spectra for LCeMO agrees reasonably well with the calculated Mn 3d PDOS using the LSDA+U method. The LSDA+U calculation predicts a half-metallic ground state for LCeMO.

Photoemission band structure of La0.7(Ca, Ce)0.3MnO3 thin films and a La0.9Ca0.1CoO3 crystal

“…So, we believe that this is a common feature of all investigated compounds. But, there is some controversy whether this emission comes from Ce 4f electrons as suggested in [9] or from Mn or Co3d electrons. We believe that the latter possibility would be more probable because we detected the strongest emission at −1.0 eV for cobaltite.…”

“…[7][8][9][10][11][12][13][14], including a high energy resolution photoemission experiments using synchrotron radiation [7][8][9][10] and the angle-resolved photoemission spectroscopy (ARPES) [13,14]. Some reference experimental information relevant to the study were published in our previous paper on X-ray photoemission [15] as well as in [9] for La 0.7 Ce 0.3 MnO 3 . A few band structure calculations for these systems were presented in [7,9,10,[16][17][18][19].…”

“…Some reference experimental information relevant to the study were published in our previous paper on X-ray photoemission [15] as well as in [9] for La 0.7 Ce 0.3 MnO 3 . A few band structure calculations for these systems were presented in [7,9,10,[16][17][18][19]. We did not find any photoemission study 0925 The aim of the paper is to present the results of the angle-resolved photoemission spectroscopy (ARUPS) in epitaxially MBE grown La 0.7 (Ca, Ce) 0.3 MnO 3 thin films and of a La 0.9 Ca 0.1 CoO 3 crystal in comparison with our previous Xray/ultraviolet (XPS/UPS) photoemission studies [15] and with other theoretical band structure calculations [9,[16][17][18][19].…”

“…A few band structure calculations for these systems were presented in [7,9,10,[16][17][18][19]. We did not find any photoemission study 0925 The aim of the paper is to present the results of the angle-resolved photoemission spectroscopy (ARUPS) in epitaxially MBE grown La 0.7 (Ca, Ce) 0.3 MnO 3 thin films and of a La 0.9 Ca 0.1 CoO 3 crystal in comparison with our previous Xray/ultraviolet (XPS/UPS) photoemission studies [15] and with other theoretical band structure calculations [9,[16][17][18][19]. In order to see the changes in the valence bands among the investigated manganates and the cobaltite we have recorded the ARUPS spectra for three selected specimens: La 0.7 Ca 0.3 MnO 3 , La 0.7 Ce 0.3 MnO 3 and La 0.9 Ca 0.1 CoO 3 with different ions of the mixed-valent states: the Mn 3+ (d 4 )/Mn 4+ (d 3 ), the Mn 2+ (d 5 )/Mn 3+ (d 4 ) and the Co 3+ (d 6 )/Co 4+ (d 5 ) participating in the double exchange interaction, respectively.…”

Point-contact Andreev-reflection spectroscopy of doped manganites: Charge carrier spin-polarization and proximity effects (Review Article)

“…For the first time direct experimental evidence of half-metallic density of states in ferromagnetic La 0.7 Ca 0.3 MnO 3 was obtained by scanning tunneling spectroscopy by Wei et al [44]. These results were then confirmed by optical [5,[45][46][47][48] and transport measurements [15,[22][23][24][25][26][27][28][29][49][50][51][52][53][54][55]. However, it should be taken into account that different experiments yield quite different value of spin polarization (see Table 1).…”