Abstract
The body-centered-tetragonal antiferromagnet was recently identified as a Weyl nodal-line semimetal that exhibits the topological Hall effect below its reported antiferromagnetic (AFM) ordering temperature K which we find to be K. The ions are located at the corners and body centers of the unit cells. exhibits A-type antiferromagnetic order below , where the spin-7/2 moments are ferromagnetically aligned in the plane with the Eu moments in adjacent Eu planes along the axis aligned antiferromagnetically. Low-field magnetization versus field data at K with the field aligned in the plane are reported that exhibit anomalous positive curvature up to a critical field at which a second-order transition occurs with kOe for and kOe for . For larger fields, the linear behavior is followed until the critical field is reached at which all moments become aligned with the applied field. A theory is formulated for K that fits the observed behavior at K well, where domains of -type AFM order with fourfold rotational symmetry occur in the AFM state in zero field. The moments in the four domains reorient to become almost perpendicular to at , followed by increasing canting of all moments toward the field with increasing field up to which is reported to be 71 kOe. A first-order transition in at is predicted by the theory for K when is at a small angle from the [1,0,0] direction.
5 More- Received 29 September 2022
- Accepted 9 January 2023
DOI:https://doi.org/10.1103/PhysRevB.107.024421
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