# A new magnetic phase in the nickelate perovskite TlNiO$_3$

## TL;DR

This paper reports the discovery of a previously unknown magnetic phase in TlNiO₃ that exists above its Néel temperature, observed through NMR and muon spin rotation, and is influenced by external magnetic fields.

## Contribution

It provides experimental evidence for a second magnetic phase in TlNiO₃ above the known Néel temperature, a novel finding in nickelate perovskites.

## Key findings

- Existence of a second magnetic phase in TlNiO₃ above T_N.
- The new phase persists up to T_N* = 202 K.
- The phase is suppressed by a 1 T magnetic field.

## Abstract

The RNiO$_3$ perovskites are known to order antiferromagnetically below a material-dependent N\'eel temperature $T_\text{N}$. We report experimental evidence indicating the existence of a second magnetically-ordered phase in TlNiO$_3$ above $T_\text{N} = 104$ K, obtained using nuclear magnetic resonance and muon spin rotation spectroscopy. The new phase, which persists up to a temperature $T_\text{N}^* = 202$ K, is suppressed by the application of an external magnetic field of approximately 1 T. It is not yet known if such a phase also exists in other perovskite nickelates.