Since the European Union introduced its Circular Economy (CE) Action Plan in 2015, CE research has expanded rapidly. However, the structure of this emerging field - both in terms of its constituent disciplines and researcher dynamics - remains poorly understood. To address this gap, we analyze over 25,000 CE-related publications from Scopus by combining conventional bibliometric approaches with advanced machine learning techniques, including text embeddings and clustering. This hybrid method enables both a macro-level mapping of research domains and a micro-level investigation of individual researchers' disciplinary backgrounds and collaborations. We classify CE research into 16 distinct clusters, identifying the original disciplines of researchers and visualizing patterns of interdisciplinary collaboration. Building on this foundation, we ask: Which CE-related research domains receive the most attention in academic and policy contexts? And how are different types of interdisciplinary collaboration associated with research impact? Our findings show that research in business and management attracts substantial academic and policy attention, while engineering research - though less visible - tends to achieve higher funding success. This suggests a positive dynamic in which the former draws attention to CE issues and the latter secures the economic resources necessary to realize them. We further demonstrate that CE papers co-authored by researchers from different disciplines tend to show higher research impact than intradisciplinary work. Qualitative case analyses also highlight this tendency. Centered particularly on collaborations between business-oriented and engineering-oriented disciplines, our findings underscore the importance of interdisciplinary efforts in CE research and offer insights for guiding future cross-disciplinary engagement in the field.