  The two-dimensional organic conductor lambda-(BETS)2FeCl4 has an unusual
phase diagram as a function of temperature and magnetic field that includes a
paramagnetic metal (PM) phase, an antiferromagnetic insulating (AFI) phase, and
a field-induced superconducting phase [S. Uji, H. Kobayashi, L. Balicas, and
James S. Brooks, Adv. Mater. 14, 243 (2002), and cited references]. Here, we
report a preliminary investigation of the PM and AFI phases at 9.0 T over the
temperature range 2.0-180 K that uses proton NMR measurements of the spectrum,
the spin-lattice relaxation rate (1/T1), and the spin echo decay rate (1/T2).
The sample is asmall single crystal whose mass is approximately 3 micrograms
(approximately 2E16 protons). Its small size creates several challenges that
include detecting small signals and excluding parasitic proton signals that are
not from the sample [H. N. Bachman and I. F. Silvera, J. Mag. Res. 162, 417
(2003)]. These strategies and other techniques used to obtain viable signals
are described.
