Tunable intersublattice exchange coupling drives magnetic evolution in Mn$_{3+x}$Ga$_{1-x}$C ($0 \le x \le 0.60$)

TL;DR

This study explores how tunable intersublattice exchange interactions in Mn$_{3+x}$Ga$_{1-x}$C drive magnetic phase transitions and influence transport properties, revealing mechanisms for designing high-temperature antiperovskite magnetic materials.

Contribution

It uncovers the role of intersublattice exchange coupling in magnetic evolution and transport phenomena in Mn$_{3+x}$Ga$_{1-x}$C, combining experimental and first-principles insights.

Findings

Magnetic ground state transitions from antiferromagnetic to ferrimagnetic with increasing x.

Maximum saturation magnetic moment of 3.63 μ_B at x=0.10.

Topological Hall resistivity peaks at x=0.20, indicating complex spin textures.

Abstract

We investigate the magnetic and transport evolution in Mn$_{3+x}$Ga$_{1-x}$C ($0 \le x \le 0.60$), where Mn substitution at corner Ga sites induces lattice contraction and suppresses the antiferromagnetic order of Mn$_3$GaC. As $x$ increases, the magnetic ground state of the system undergoes a sequential transition from an antiferromagnetic state, via a canted ferrimagnetic state, to a robust ferrimagnetic state, accompanied by a surge in the magnetic ordering temperature. Saturation magnetic moments reaches a maximum of 3.63~$\mu_{\mathrm{B}}$/f.u. at $x = 0.10$, whereas the topological Hall resistivity peaks at 1.47~$\mu\Omega\cdot$cm for $x = 0.20$ before decreasing with further doping. First-principles calculations demonstrate a $\sim\!40^{\circ}$ canting of face-centered Mn moments at $x = 0.20$, signifying spin frustration, and an eventual antiparallel alignment of face-centered and corner-site Mn moments at higher $x$. These results reveal that intersublattice antiferromagnetic coupling governs the magnetic transformation and emergent transport phenomena, thus providing a microscopic foundation for designing high-ordering-temperature antiperovskites.