Effect of magnesium doping on the orbital and magnetic order in LiNiO2

TL;DR

This study investigates how magnesium doping affects magnetic and orbital order in LiNiO2, revealing a disordered, fluctuating state without stabilized order and identifying magnon excitations and orbital occupancy characteristics.

Contribution

It provides new insights into the magnetic and orbital behavior of LiNiO2 under magnesium doping using MuSR and ESR techniques.

Findings

Magnesium doping does not stabilize magnetic or orbital order.

A disordered, slowly fluctuating state appears below 12 K.

Magnons are excited on the ESR timescale, with observed g factor anisotropy.

Abstract

In LiNiO2, the Ni3+ ions, with S=1/2 and twofold orbital degeneracy, are arranged on a trian- gular lattice. Using muon spin relaxation (MuSR) and electron spin resonance (ESR), we show that magnesium doping does not stabilize any magnetic or orbital order, despite the absence of interplane Ni2+. A disordered, slowly fluctuating state develops below 12 K. In addition, we find that magnons are excited on the time scale of the ESR experiment. At the same time, a g factor anisotropy is observed, in agreement with $| 3z^{2}-r^{2}>$ orbital occupancy.