Abstract
We report the magnetic and electronic transport properties of the inversion and time-reversal symmetry breaking Weyl semimetal NdAlGe. This material is analogous to NdAlSi, whose helical magnetism presents a rare example of a Weyl-mediated collective phenomenon, but with a larger spin-orbit coupling. Our neutron diffraction experiments revealed that NdAlGe, similar to NdAlSi, supports an incommensurate spin density wave (Tinc=6.8 K) whose spins are predominantly pointing along the out-of-plane direction and have a small helical spin canting of 3∘. The spin density wave has a long wavelength of ≈35 nm and transitions to a commensurate ferrimagnetic state below Tcom=5.1K. Using small-angle neutron scattering, we showed that the zero-field cooled ferrimagnetic domains form stripes in real space with characteristic length scales of 18 and 72 nm parallel and perpendicular to the [110] direction, respectively. Interestingly, for the transport properties, NdAlSi does not exhibit an anomalous Hall effect (AHE) that is commonly observed in magnetic Weyl semimetals. In contrast to NdAlSi, we identify two different AHE regimes in NdAlGe that are, respectively, governed by intrinsic Berry curvature and extrinsic disorders/spin fluctuations. Our paper suggests that Weyl-mediated magnetism prevails in this group of noncentrosymmetric magnetic Weyl semimetals NdAlX, but transport properties including AHE are affected by material-specific extrinsic effects such as disorders, despite the presence of prominent Berry curvature.
| Original language | English |
|---|---|
| Article number | 034202 |
| Journal | Physical Review Materials |
| Volume | 7 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2023 |
Funding
H.-Y.Y. thanks Chunli Huang, Hiroaki Ishizuka, Ilya Sochnikov, Christopher Eckberg, Allan MacDonald, Inti Sodemann, Yaroslav Tserkovnyak, and Collin Broholm for fruitful discussions. This material is based upon work supported by AFOSR Grant No. FA2386-21-1-4059. The work at TIFR Mumbai was supported by the Department of Atomic Energy of the government of India under Project No. 12-R&D-TFR-5.10-0100. We acknowledge the support of NIST. The work at Northeastern University was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences Grant No. DE-SC0022216 and benefited from Northeastern University's Advanced Scientific Computation Center and the Discovery Cluster and the National Energy Research Scientific Computing Center through DOE Grant No. DE-AC02-05CH11231. H.L. acknowledges support by the National Science and Technology Council in Taiwan under Ministry of Science and Technology (MOST) Grant No. 111-2112-M-001-057-MY3. The identification of any commercial product or trade name does not imply endorsement or recommendation by NIST. A portion of this research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by ORNL.