Summary While transverse and longitudinal spin fluctuation (TSF and LSF) are generally considered independent, their correlation in real materials remains largely unexplored. Here, we studied TSF and LSF in square-lattice, spin-half model system (SrIrO3)2/(Sr1−xCaxTiO3)120 superlattices using magnetic resonant X-ray scattering, magnetic coercivity, and octahedral rotation measurements. These reveal a systematic variation in TSF driven by competition between c axis and a axis magnetic anisotropy, while magnetotransport measurements at the Néel temperatures unveil x-dependent LSF. Interestingly, TSF and LSF are modulated in approximately opposite ways, with close correlation giving rise to a rare negative, parabolic magnetoresistance in this intermediate-correlation regime.
Men et al. (Wed,) studied this question.