Antiferromagnetic resonance truncated by the spin-flop transition

Antiferromagnetic resonance truncated by the magnetic spin-flop transition at the thermodynamic critical field has been observed in GdAlO3. Because of the new phenomenon of truncation resulting from the finite linewidth of the resonances, the first-order nature of the transition is directly observable and the superheating can be determined quantitatively. © 1970 The American Physical Society.