Abstract-Complementary terahertz absorption and inelastic neutron study of the dynamic anisotropy contribution to zone-center spin waves in a canted antiferromagnet NdFeO3

Evan Constable, D. L. Cortie, Joseph Horvat, R. A. Lewis, Zhenxiang Cheng, Guochu Deng, Shixun Cao, Shujuan Yuan, and Guohong Ma
https://journals.aps.org/prb/abstract/10.1103/PhysRevB.90.054413

We employ a combination of pulsed- and continuous-wave polarized terahertz spectroscopy techniques to probe temperature-dependent spin waves in the antiferromagnet NdFeO3. Our optical data span 1.6–467 K and reveal a conspicuous spin reorientation between 110 and 170 K, during which the lower-energy mode softens completely. Complementary inelastic neutron scattering reveals that the frequencies of the optically excited spin waves are consistent with a temperature-variable spin gap in the low-energy spin-wave dispersion of NdFeO3. The result links the temperature dependence of the spin waves to a dynamic in-plane anisotropy. The magnetic anisotropy is calculated based on the results of the optical measurements. The change observed in the anisotropy energy along the a and c crystal axes suggests that the spin reorientation evident in NdFeO3 is driven by temperature-dependent in-plane anisotropy.

DOI: http://dx.doi.org/10.1103/PhysRevB.90.054413

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