In situ photoemission study of the room-temperature ferromagnet ZnGeP_2:Mn

TL;DR

This study investigates the chemical states and magnetic properties of Mn-doped ZnGeP2 using photoemission spectroscopy, revealing Mn substitution behavior, electronic state changes with depth, and potential hole doping mechanisms.

Contribution

It provides new insights into the chemical states and electronic structure of Mn in ZnGeP2, highlighting the depth-dependent transition from itinerant to localized Mn electrons.

Findings

Mn substitution for Zn induces ferromagnetism above room temperature.

Mn 3d electrons transition from itinerant to localized with depth.

Dilute divalent Mn species coexist with metallic Fermi edge in deep regions.

Abstract

The chemical states of the ZnGeP$_{2}$:Mn interface, which shows ferromagnetism above room-temperature, has been studied by photoemission spectroscopy. Mn deposition on the ZnGeP$_2$ substrate heated to 400$^{\circ}$C induced Mn substitution for Zn and then the formation of metallic Mn-Ge-P compounds. Depth profile studies have shown that Mn 3$d$ electrons changed their character from itinerant to localized along the depth, and in the deep region, dilute divalent Mn species ($\textless$ 5 % Mn) was observed with a coexisting metallic Fermi edge of non-Mn 3$d$ character. The possibility of hole doping through Mn substitution for Ge and/or Zn vacancy is discussed.