Weyl nodal ring states and Landau quantization with very large magnetoresistance in square-net magnet EuGa${}_4$

Abstract

Magnetic topological semimetals (TSMs) allow for an effective control of the topological electronic states by tuning the spin configuration, and therefore are promising materials for next-generation electronic and spintronic applications. Of magnetic TSMs, Weyl nodal-line (NL) semimetals likely have the most tunability, and yet they are the least experimentally studied so far due to the scarcity of material candidates. Here, using a combination of angle-resolved photoemission spectroscopy and quantum oscillation measurements, together with density functional theory calculations, we identify the square-net compound EuGa4 as a new magnetic Weyl nodal ring (NR) semimetal, in which the line nodes form closed rings in the vicinity of the Fermi level. Remarkably, the Weyl NR states show distinct Landau quantization with clear spin splitting upon application of a magnetic field. At 2 K in a field of 14 T, the transverse magnetoresistance of EuGa4 exceeds 200,000%, which is more than two orders of magnitude larger than that of other known magnetic TSMs. High field magnetoresistance measurements indicate no saturation up to 40 T. Our theoretical model indicates that the nonsaturating MR naturally arises as a consequence of the Weyl NR state. Our work thus point to the realization of Weyl NR states in square-net magnetic materials, and opens new avenues for the design of magnetic TSMs with very large magnetoresistance.

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Cited by in corpus (7)

• Charge-density wave transition in magnetic topological semimetal EuAl${}_4$
• Experimental progress in Eu(Al,Ga)${}_4$ topological antiferromagnets
• Revealing the EuCd_{2}As_{2} Semiconducting Band Gap via n-type La-Doping
• Incommensurate Transverse Peierls Transition
• Origin of multiple skyrmion phases in EuAl4
• Correlation between Complex Spin Textures and the Magnetocaloric and Hall Effects in Eu(Ga${}_{1-x}$Al${}_x$)${}_4$ ($x$ = 0.9, 1)
• Fermi surface and Berry phase analysis for Dirac nodal line semimetals: cautionary tale to SrGa${}_2$ and BaGa${}_2$