Weak magnetic anisotropy in GdRh$_2$Si$_2$ studied by magnetic resonance

摘要

The antiferromagnetically (AFM) ordered state of GdRh$_{2}$Si$_{2}$ whichconsists of AFM-stacked ferromagnetic layers is investigated by magneticresonance spectroscopy. The almost isotropic Gd$^{3+}$ paramagnetic resonancebecomes anisotropic in the AFM ordered region below 107 K. The emerginginternal anisotropic exchange-fields are still small enough to allow aninvestigation of their magnetization dynamics by using a standardmicrowave-frequency magnetic resonance technique. We could characterize thisanisotropy in detail in the ferromagnetic layers of the excitation at 9 and 34GHz. We derived a resonance condition for the AFM ordered phase to describe theweak in-plane anisotropic behaviour in combination with a mean-field analysis.