May be Jorn Utzon (from Danemark)? If you ask a Foreign (like me) about a building in Australia, most of us will say: Sidney Opera House. You will find many things written about it. He has influenced international architecture (and received many international architecture prizes; Pritzker-2003). But also "Local Australian Architecture": Australian Institute of Architects has "Jorn Utzon Award", "International Utzon Workshop"...You may look in your library for:

Building a masterpiece : the Sydney Opera House. Watson, Anne (2006)

This web may help you to locate other "Australian Migrant Architects", not so "well known" (out of Australia) :

   http://www.australia.gov.au/about-australia/australian-story/austn-architecture

American architect Walter Burley Griffin (Parliament House Canberra)

Charles Reade (British garden city militant, actively promoting garden city idea in Australia)

John Sulman, Australian architect active in Europe-based international town planning societies (including IFHTP)

Edmund Wright

http://www.architectsdatabase.unisa.edu.au/arch_full.asp?Arch_ID=17