Correspondent: Jonathan Gold
Exchange unit: Johns Hopkins University
Relativistic quasi-particles in Weir semi-metal are the source of exotic electronic properties, such as surface Fermi arc, anomalous Hall effect and negative magnetoresistance, all of which are observed in practical materials. Although these phenomena highlight the influence of fermions on electron transport characteristics, people know little about the collective phenomena they may support. Recently, Jonathan Gaudet of Johns Hopkins University and others published a research paper entitled "Weyl-mediated Mechanical Magnetism in ndalsi" in the internationally renowned journal Nat. Mater Here, they report a Weyl semimetal, NdAlSi, which provides an example. Using neutron diffraction, they found a long-wavelength spiral magnetic sequence in NdAlSi, and its periodicity is related to the nested vector between two topological non-three-state Fermi bags. They use density functional theory and quantum oscillation measurement to describe its characteristics. They further show that the bond orientation Dzyaloshinskii- Moriya interaction related to Weyl exchange process promotes the chiral transverse component of spin structure. Their work provides a rare example of collective magnetism driven by fermions.
Graph 1: A, b, the structure of non-central symmetric NdAlSi with space group I4 1md (S.G.109; ; A) and its associated first Brillouin zone are shown in b. There are two simple mirrors mx and my, and two sliding mirrors MX and MX. These are shown as light red and green planes in B. Z-γ-X path is in the green mx mirror, and γ-S-N-S'-Z-γ path is in the red MX mirror. C, refinement of neutron diffraction data of single crystal nucleus collected at 100K, in which Fobs and Fcalc are observed and calculated structural factors respectively. The black line with a slope of 1 is displayed as visualization. The error line is discussed in the method. By subtracting the heat capacity of nonmagnetic LaAlSi, the temperature dependence of magnetic heat capacity (main panel) and magnetic entropy (Smag) of D, NdAlSi is separated from the net heat capacity. The red line represents the estimation of the energy scheme of the spin orbit manifold of Nd3+ ions in NdAlSi.
Original link:
/articles/s 4 1563-02 1-0 1062-8