Possible spin frustration in Nd$_2$Ti$_2$O$_7$ probed by muon spin relaxation

TL;DR

This study uses muon spin relaxation to investigate magnetic behavior in Nd$_2$Ti$_2$O$_7$ and NdLaTi$_2$O$_7$, revealing signs of spin frustration and cooperative magnetic states at low temperatures.

Contribution

It provides experimental evidence of spin frustration and cooperative magnetic behavior in Nd$_2$Ti$_2$O$_7$ through muon spin relaxation measurements.

Findings

Muon relaxation rate increases then levels off below 10 K.

Evidence of spin frustration and cooperative behavior.

Ferromagnetic ground state at 0.3 K.

Abstract

Muon spin relaxation on Nd$_2$Ti$_2$O$_7$ (NTO) and NdLaTi$_2$O$_7$ (NLTO) compounds are presented. The time spectra for both compounds are as expected for the paramagnetic state at high temperatures, but deviate from the exponential function below about 100 K. The muon spin relaxation rate increases with decreasing temperature firstly, and then levels off below about 10 K, which is reminiscent of the frustrated systems. An enhancement of the relaxation rate by a longitudinal field in the paramagnetic state is observed for NTO, and eliminated by a magnetic dilution for the NLTO sample. This suggests that the spectral density is modified by a magnetic dilution and thus indicates that the spins behave cooperatively rather than individually. Zero-field measurement at 0.3 K indicates that the magnetic ground state for NTO is ferromagnetic.