Complex spin dynamics induced metamagnetic phase transitions in Dirac semimetal EuAuBi

TL;DR

This study reveals complex magnetic phase transitions and spin textures in EuAuBi, a Dirac semimetal, highlighting the coexistence of momentum-space and real-space Berry curvature effects and their influence on electronic properties.

Contribution

It provides the first detailed magnetic phase diagram of EuAuBi, combining experimental and theoretical insights into its spin dynamics and topological features.

Findings

Identification of three magnetic phases at different temperatures

Observation of field-induced non-trivial spin textures

Evidence of interplay between spin textures and electronic transport

Abstract

We report a comprehensive investigation of the physical properties of the Dirac semimetal compound EuAuBi single crystals, using neutron diffraction, magnetization, electrical transport, and specific heat measurements. EuAuBi crystallizes in a hexagonal structure with space group P63mc (No. 186). First-principles calculations using density functional theory characterize it as a Dirac semimetal, with a notable band-crossing in proximity to the Fermi level (EF ) along the {\Gamma}-A direction. The crystal exhibits three distinct magnetic phases at 4 K (TN1), 3.5 K (TN2), and 2.8 K (TN3)as observed from magnetic and specific heat measurements. However, zero-field neutron diffraction resolves only two magnetic phases: a commensurate antiferromagnetic phase and a canted antiferromagnetic phase. Field-dependent ac and dc magnetization measurements uncover field-induced non-trivial spin textures in the magnetic field range 1.5 to 3 T, manifested as a tilted plateau in the magnetization curves. The interplay between conduction carriers and these spin textures is further evidenced by unique features in the magnetic field-dependent longitudinal resistivity in the system. Finally, we present a comprehensive magnetic phase diagram of EuAuBi, highlighting diverse spin alignments present in the material. EuAuBi thus emerges as a rare material system in which both momentum-space and real-space Berry curvature effects may coexist, providing a unique opportunity to investigate their interplay.