Magnetic field-tuned magnetic order and metamagnetic criticality in non-stoichiometric CeAuBi$_2$

TL;DR

This study investigates how non-stoichiometry and magnetic field influence magnetic order and criticality in CeAuBi$_2$, revealing complex phase transitions and the role of disorder in smearing metamagnetic behavior.

Contribution

It demonstrates that Au vacancies in CeAuBi$_2$ can tune magnetic transitions and critical behavior, with a detailed phase diagram linking field, temperature, and disorder effects.

Findings

Large magnetic anisotropy with a spin-flop transition at 75 kOe

Transition from second-order to first-order magnetic phase transition

Disorder from Au vacancies smears metamagnetic features

Abstract

We present a detailed study of magnetization, resistivity, heat capacity, and X-ray and neutron powder diffraction measurements performed on single crystals of non-stoichiometric CeAuBi$_2$, Au deficiency 18$\%$, a strongly correlated antiferromagnet with N\'eel temperature T$_N$ = 13.2 K. Field-dependent magnetization measurements reveal a large magnetic anisotropy at low temperatures with an easy axis along the crystallographic c-axis, in which direction a spin-flop transition exhibits strong features in magnetization, specific heat, and resistivity at H$_c$ = 75 kOe. The constructed temperature-field phase diagram connects this transition to the suppression of magnetic order, which evolves from a second-order nature into a first-order transition that bifurcates at the spin-flop into three transitions below 1 K. The smoothed nature of the metamagnetic transitions in non-stoichiometric CeAuBi$_2$ is well described by an Ising model with weak quenched disorder, suggesting that the presence of Au vacancies is sufficient to smear the complex metamagnetic behavior and tune the critical behavior of magnetic order.