The Access Network is an organization that supports vibrant interactions among students and faculty who advocate for equity work in the physical sciences. This paper uses McGee and Bentley's framework of "equity ethic" (EE) to understand how Access student leaders adopt and refine a commitment to equity and social justice work within the physical sciences. In McGee and Bentley's study of STEM students of color, they define EE as students' sense of altruism and collectivism within and outside of their communities. Through interviews with student leaders, we model components of students' EEs and how their EEs are influenced by their participation in Access. Student accounts illustrate that they are invested in improving equity within their disciplinary communities and see progress toward these goals as an important measure of success. Our findings highlight how students are already infusing an EE into their professional physics activities. This research suggests that student leaders benefit from having opportunities to articulate and refine critiques of disciplinary culture, and connect their EE to their professional practices. These accounts suggest that this work occurs in conversation with other equity leaders around issues of social justice.