Antiferromagnetic d-electron exchange via a spin-singlet pi-electron ground state in an organic conductor.
Electron spin resonance reveals the spin behavior of conduction (pi) and localized (d) electrons in beta-(BDA-TTP)2MCl4 (M=Fe, Ga). Both the Ga3+(S=0) and Fe3+(S=5/2) compounds exhibit a metal-insulator transition at 113 K with the simultaneous formation of a spin-singlet ground state in the pi electron system of the donor molecules. The behavior is consistent with charge ordering in beta-(BDA-TTP)2MCl4 at the metal-insulator transition. At 5 K, the Fe3+ compound orders antiferromagnetically, even though the pi electrons, which normally would facilitate magnetic exchange, are localized nonmagnetic singlets.
Tokumoto
T
T
National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
Brooks
J S
JS
Oshima
Y
Y
Choi
E S
ES
Brunel
L C
LC
Akutsu
H
H
Kaihatsu
T
T
Yamada
J
J
van Tol
J
J