Paramagnetic resonance in La2NiMnO6 probed by impedance and lock-in detection techniques

TL;DR

This study detects paramagnetic resonance in La2NiMnO6 at room temperature using cavity-less impedance and lock-in techniques across 1-5 GHz, revealing a large g-factor and strong spin-orbit coupling.

Contribution

It introduces two cavity-less methods for detecting paramagnetic resonance in La2NiMnO6 at room temperature, expanding experimental capabilities.

Findings

Resonance fields increase linearly with frequency.

Large g-factor of 2.1284 indicates strong spin-orbit coupling.

Methods successfully characterize magnetic properties of La2NiMnO6.

Abstract

We report the detection of paramagnetic resonance in the double perovskite La2NiMnO6 at room temperature for microwave magnetic fields with frequencies, f = 1 GHz to 5 GHz, using two cavity-less methods. We use an indirect impedance method which makes use of a radio frequency impedance analyzer and a folded copper strip coil for the frequency range f = 1 to 2.2 GHz. In this method, when an applied dc magnetic field is swept, high-frequency resistance of the strip coil exhibits a sharp peak and the reactance curve crosses zero exhibiting resonance. A lock-in based broadband setup using a coplanar waveguide for microwave excitation was used for f = 2 to 5 GHz The resonance fields (Hr) obtained from both the techniques increase linearly with frequency and a large spectroscopic g-factor, equal to 2.1284, which supports the presence of Ni2+ cation with strong spin-orbit coupling. Line shape analysis and analytical fitting were performed to characterize the material in terms of its initial susceptibility and damping parameters.