Resonant photoemission spectroscopy study of insulator-to-metal transition in Cr- and Ru-doped Nd_{1/2}A_{1/2}Mn_{1-y} O_{3} (A=Ca, Sr)

TL;DR

This study uses resonant photoemission spectroscopy to analyze how dilute Cr and Ru doping induces insulator-to-metal transitions and ferromagnetism in Nd_{1/2}A_{1/2}MnO_{3} manganites, revealing their electronic structures.

Contribution

It provides detailed electronic structure insights into Cr- and Ru-doped NAMO manganites, highlighting their metallic states and the role of dopant states in phase transitions.

Findings

Cr- and Ru-doped NAMO exhibit clear metallic Fermi edges.

Cr 3d states are located ~1.3 eV below E_F and do not contribute to conduction.

Dopant-induced ferromagnetism correlates with electronic structure changes.

Abstract

Electronic structures of very dilute Cr- or Ru-doped Nd_{1/2}A_{1/2}MnO_{3} (NAMO; A=Ca, Sr) manganites have been investigated using the Mn and Cr 2p -> 3d resonant photoemission spectroscopy (PES). All the Cr- and Ru-doped NAMO systems exhibit the clear metallic Fermi edges in the Mn e_g spectra near E_F, consistent with their metallic ground states. The Cr 3d states with t^3_{2g} configuration are at ~ 1.3 eV below E_F, and the Cr e_{g} states do not participate in the formation of the band near E_F. Cr- and Ru-induced ferromagnetism and insulator-to-metal transitions can be understood with their measured electronic structures.