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ID 18814
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creator
Hosokoshi, Yuko
Nakazawa, Yasuhiro
Takizawa, Kohichi
Nakano, Hiroki
Takahashi, Minoru
Goto, Tsuneaki
abstract
Stable organic biradical crystals PNNNO, F2PNNNO, and PIMNO of the PNNNO family were synthesized. {PNNNO=2-[4′- (N-tert-butyl-N-oxyamino)phenyl]-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazol-1- oxyl 3-oxide, F2PNNNO= 2-[2′,6′,-difluoro-4′-(N-tert-butyl-7V-oxyamino)phenyl]-4,4,5, 5-tetramethyl-4, 5-dihydro-1H-imidazol-1-oxyl 3-oxide, PIMNO=2-[4′-(N-tert-butyl-N-oxyamino)-phenyl]-4,4,5, 5-tetramethyl-4,5-dihydro-1H-imidazol-1-oxyl.} PNNNO and PIMNO crystallize to form quasi-one-dimensional lattices, but F2PNNNO to form a quasi-two-dimensional lattice. The temperature dependences of the susceptibility and the high-field magnetization process up to 34 T were measured down to 0.5 K. The results are analyzed by comparing with the theoretical calculations based on the crystal structures. PNNNO and PIMNO are considered to be antiferromagnetic Heisenberg spin chains consisting of S=1/2 spin pairs (dimers) in which the two spins are coupled ferromagnetically. At low temperatures, an antiferromagnetic ordering occurs in these crystals, which is confirmed by the thermodynamic discussion through specific heat measurements. On the other hand, F2PNNNO is thought to be a two-dimensional Heisenberg system, in which the spin pairs are connected by two types of antiferromagnetic interactions. The ground state is singlet. The high-field magnetization process shows a two-step saturation with a plateau of the half value of the saturation magnetization.
journal title
Physical Review B - Condensed Matter and Materials Physics
volume
Volume 60
issue
Issue 18
start page
12 924
end page
12 932
date of issued
1999-11-01
publisher
American Physical Society
issn
1098-0121
ncid
publisher doi
language
eng
nii type
Journal Article
HU type
Journal Articles
DCMI type
text
format
application/pdf
text version
publisher
rights
Copyright (c) 1999 The American Physical Society.
relation url
department
Graduate School of Science