Electronic and Magnetic Properties of Sr and Ca Doped Lanthanum Manganites from First-Principles

TL;DR

This study uses first-principles calculations to analyze the electronic and magnetic behaviors of Sr and Ca doped lanthanum manganites, elucidating their complex properties including colossal magnetoresistance.

Contribution

It provides a detailed first-principles analysis of the electronic and magnetic mechanisms underlying the properties of doped lanthanum manganites, highlighting the balance of various states and interactions.

Findings

Electronic properties result from a balance of delocalized and localized states.

Magnetic properties are governed by superexchange and ferromagnetic couplings.

Colossal magnetoresistance arises from magnetic domain alignment and electron mobility.

Abstract

The complicated electronic, magnetic, and colossal magnetoresistant (CMR) properties of Sr and Ca doped lanthanum manganites can be understood by spin-polarized first-principles calculations. The electronic properties can be attributed to a detailed balancing between Sr and Ca induced metal-like O 2p and majority-spin (majority-spin) Mn eg delocalized states and the insulator-like minority-spin (minority-spin) Mn t2g band near the Fermi level (EF). The magnetic properties can be attributed to a detailed balancing between O mediated antiferromagnetic superexchange and delocalized majority-spin Mn eg-state mediated ferromagnetic spin-spin couplings. While CMR can be attributed to the lining up of magnetic domains trigged by the applied magnetic field, which suppresses the trapping ability of the empty Mn t2g states that resists the motion of conducting Mn majority-spin eg electrons.