Naslov
Ferromagnetic and merohedral ordering in powder and crystalline tetrakis (dimethylamino) ethylene (TDAE)-C60

Autori
Mihailović, Dragan ; Pokhodnya, Konstantin ; Omerzu, Aleš ; Venturini, P. ; Blinc, Robert ; Cevc, P. ; Pratt, F. ; Chow, K.H.

Izvornik
Synthetic metals (0379-6779) 77 (1996), 1-3; 281-285

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
fullerene ; ferromagnetism ; crystals ; tetrakis(dimethylamino)ethylene

Sažetak
A.c, susceptometry and electron spin resonance (ESR) measurements on crystals and powders show direct evidence of coupling between spin and molecular merohedral degrees of freedom in tetrakis (dimethylamino) ethylene (TDAE)-C-60 (16 < T-c < 26 K). Ordering the spins using an external field in the magnetic phase is shown to imprint a merohedral order. Conversely, merohedrally ordering the C-60 molecules at high temperature influences the low-temperature magnetic transition temperature. The merohedral disorder gives rise to a distribution of pi- electron exchange interactions between spins on neighbouring C-60 molecules, suggesting a microscopic origin for the observed spin- glasslike behaviour in the magnetic state. ESR measurements on single crystals of TDAE-C-60 show a frequency shift which is maximum when the absolute value of applied field \H-ext\ is along the crystallographic a axis. On the basis of the present data we suggest the material to be a ferromagnet, with the magnetic axis along a and with the dipole-dipole interactions being responsible for the large ESR line shifts and line broadening in the magnetic phase. New IR reflectivity data suggest a low- frequency excitation unobserved to date, whose origin could be a Drude peak, indicating a metallic ground state or a possible low-frequency charge density wave (CDW) excitation.

Izvorni jezik
Hrvatski

Znanstvena područja
Fizika, Interdisciplinarne prirodne znanosti

POVEZANOST RADA