Na$_5$Co$_{15.5}$Te$_6$O$_{36}$: an $S$ = 1/2 stacked Ising kagome antiferromagnet with a partially disordered ground state

TL;DR

This study investigates the magnetic properties and phase transitions of Na$_5$Co$_{15.5}$Te$_6$O$_{36}$, a rare $S$=1/2 Ising kagome antiferromagnet with a partially disordered ground state, revealing complex magnetic behavior and potential for further exploration.

Contribution

The paper reports the discovery of a partially disordered ground state and detailed magnetic phase diagram in a new $S$=1/2 Ising kagome antiferromagnet with a stacked structure.

Findings

Three magnetic transitions at 45.2 K, 35.4 K, and 20 K.

Observation of anomalous initial magnetization behavior.

Proposal of a partially disordered antiferromagnetic ground state.

Abstract

$S$ = 1/2 Ising kagome antiferromagnets (KAFs) are rare in reality. In this work, we report the magnetic ground state and field-induced transitions of an $S$ = 1/2 Ising antiferromagnet with a stacked kagome geometry, Na$_5$Co$_{15.5}$Te$_6$O$_{36}$. Upon cooling, magnetic susceptibility measurement reveals three successive magnetic transitions at $T_1$ = 45.2 K, $T_2$ = 35.4 K, and $T_3 \sim$ 20 K. When the magnetic field is applied along the Ising $c$ axis, a strikingly anomalous initial magnetization lying outside the hysteresis loop is observed below $T_3$. Through the detailed characterizations, the magnetic field $vs$ temperature phase diagram is established. A partially disordered antiferromagnetic state is proposed below $T_1$, which becomes frozen below $T_3$. Na$_5$Co$_{15.5}$Te$_6$O$_{36}$ is therefore a promising candidate for $S$ = 1/2 Ising KAFs, and this unique composite structure may shed light on the exploratory path for $S$ = 1/2 Ising KAFs.