Stripe helical magnetism and two regimes of anomalous Hall effect in NdAlGe
- Boston College, Chestnut Hill, MA (United States); Univ. of California, Los Angeles, CA (United States)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States); Univ. of Maryland, College Park, MD (United States)
- Tata Inst. of Fundamental Research, Mumbai (India)
- Rutgers Univ., Piscataway, NJ (United States); Jaypee University of Information Technology, Waknaghat (India)
- Boston College, Chestnut Hill, MA (United States)
- Northeastern Univ., Boston, MA (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States)
- Academia Sinica, Taipei (Taiwan)
Here, 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.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR); US Air Force Office of Scientific Research (AFOSR)
- Grant/Contract Number:
- AC05-00OR22725; SC0022216; AC02-05CH11231; FA2386-21-1-405
- OSTI ID:
- 1965246
- Journal Information:
- Physical Review Materials, Vol. 7, Issue 3; ISSN 2475-9953
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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