Spin-flip-driven giant magneto-transport in A-type antiferromagnet NaCrTe2

TL;DR

This paper demonstrates giant magneto-transport effects in NaCrTe2, an A-type antiferromagnet, driven by spin-flip transitions that significantly alter its electronic structure and resistance, revealing record AMR ratios.

Contribution

It reports the first observation of record-breaking AMR ratios in NaCrTe2 driven by spin-flip transitions and provides theoretical insights into the electronic and magnetic changes involved.

Findings

Achieved a -90% negative MR ratio at 10 K.

Recorded an AMR ratio of 732% at 10 K, a record value.

Theoretical calculations show a bandgap narrowing from 0.39 eV to 0.11 eV during spin-flip.

Abstract

For anisotropic magneto-resistance (AMR) effect, its value synergistically depends on the magnitudes of magneto-resistance (MR) and magneto-crystalline anisotropy energy (MAE) simultaneously. In a magnetic material, the concurrence of gigantic AMR and MR signals is rather difficult due to weak spin-lattice coupling and small MAE. Here we report the considerable magneto-transport effect in layered A-type antiferromagnetic (AFM) NaCrTe2 by realigning the spin configurations. By applying H, the antiparallel spins of adjacent layers are flipped to ferromagnetic (FM) coupling either Ising-type along c-axis or XY-type within ab-plane. Theoretical calculations reveal that the energy bandgap narrows from 0.39 eV to 0.11 eV, accompanying a transition from semiconductor (high-R state) and half-semiconductor (low-R state), respectively. Thus, gigantic negative MR ratio of -90% is obtained at 10 K. More importantly, the decrement of R along H//c is far quicker than that of H//ab because the MAE of Ising-FM state is 1017 {\mu}eV/Cr3+ lower than that of XY-FM. The distinct trends result in the AMR ratio of 732% at 10 K, which is the record value to our best knowledge. These findings unravel the intrinsic origin of magneto in NaCrTe2 and will stimulate us to exploring the H-sensitive transport property in more AFM materials.