Neutron scattering investigation of magnetic bilayer correlations in $La_{1.2}Sr_{1.8}Mn_2O_7$

TL;DR

This neutron scattering study reveals that in La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$, magnetic bilayer correlations involve strongly canted spins influenced by temperature and magnetic field, with in-plane correlations not diverging at the Curie temperature.

Contribution

The paper provides detailed insights into the magnetic correlations and spin canting in layered manganite, confirming predictions and linking magnetic behavior to electrical conductance.

Findings

Strong bilayer spin canting dependent on field and temperature

In-plane correlation length does not diverge at T_C

Magnetic Bragg intensity scales with electrical conductance

Abstract

Neutron scattering investigations of the paramagnetic correlations in the layered manganite La$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$, which exhibits colossal magnetoresistance above the Curie transition at T$_C$ = 112 K, show that spins in neighboring layers within each bilayer are strongly canted at an average angle that is dependent on both the magnetic field and temperature, as predicted by de Gennes. The in-plane correlation length does not diverge at T$_C$, although the magnetic Bragg intensity obeys critical scaling below T$_C$, with the same temperature dependence as the zero-field electrical conductance.