Metamagnetic Transition in Na$_{0.85}$CoO$_2$ Single Crystals

TL;DR

This study investigates the magnetic phase transitions in Na$_{0.85}$CoO$_2$ single crystals, revealing a field-induced metamagnetic transition along the c-axis and constructing the low-temperature magnetic phase diagram.

Contribution

It provides the first detailed characterization of the metamagnetic transition and magnetic phase diagram in Na$_{0.85}$CoO$_2$ single crystals under high magnetic fields.

Findings

Metamagnetic transition occurs at about 8T along the c-axis.

No transition observed up to 14T perpendicular to the c-axis.

Low temperature magnetic phase diagram is established.

Abstract

We report the magnetization, specific heat and transport measurements of high quality Na$_{0.85}$CoO$_2$ single crystals in applied magnetic fields up to 14T. In high temperatures, the system is in a paramagnetic phase. It undergoes a magnetic phase transition below about 20K. When the field is applied along the c-axis, the measurement data of magnetization, specific heat and magnetoresistance reveal a metamagnetic transition from an antiferromagnetic state to a quasi-ferromagnetic state at about 8T in low temperatures. However, no transition is observed in the magnetization measurements up to 14T when the field is applied perpendicular to the c-axis. The low temperature magnetic phase diagram of Na$_{0.85}$CoO$_2$ is determined.