The literature seems to promote the concept as non-positional leadership that empowers all teachers to take up leading roles but most of it appears to lack research data to support it's actual practice.
Teach For America uses the 'teacher leader' model. Try looking at their research/research done on their corps members: https://www.teachforamerica.org/our-organization/research
Muijs, D. and Harris, A. (2007) 'Teacher Leadership in (in)action: three case studies of contrasting
schools', Education Management and Administration Vol 35 pages 111-134Muijs, D. and Harris, A. (2006) Teacher led school improvement: Teacher leadership in the UK
Teachers and Teacher Education Vol 22 Issue 8 pages 961-972
Harris, A (2005) Teacher Leadership: More than a Feel Good Factor? Journal of Leadership and
Policy in Schools Volume 4, Number 3 p 201-209 ISSN 1744-5043