Control of Antiferromagnetic Dynamics in Nickelate Heterostructures

In this work we examine the dynamics and energetics of antiferromagnetic (AF) domains. A key enabler to understand and control AF domains involves the ability to image their structure and dynamics. The AF order parameter can be imaged in thin films using resonant soft x-ray diffraction, and information about their dynamics can be accessed by x-ray photon correlation spectroscopy (XPCS) measurements using coherent soft x-rays. Recent studies have revealed that the magnetic and electronic phase transitions in NdNiO₃ (NNO) can be tuned by confining the NNO layers to reduced dimensions in heterostructures. We image the AF ground state in reciprocal space for atomically layered (NdNiO₃)_m-(NdAlO₃)_n heterostructures and show that dimensional confinement enhances the phase fluctuations at AF domain boundaries. The speckle patterns acquired from coherent x-ray scattering contain information on long- and short-range correlations and the nature of AF boundaries in dimensionally confined nickelate layers. As the AF domain boundary approaches the single unit cell limit, the dynamics are enhanced. This study demonstrates an approach to characterize dimensional effects on long-range order and the ability to control AF domain configurations in oxide heterostructures.