Birchite Cd2Cu2(PO4)2SO4·5 H2 O as a model antiferromagnetic spin-1/2 Heisenberg J1-J2 chain

Masayoshi Fujihala, Harald O. Jeschke, Katsuhiro Morita, Tomohiko Kuwai, Akihiro Koda, Hirotaka Okabe, Akira Matsuo, Koichi Kindo, Setsuo Mitsuda