Na. Fortune et Yv. Sushko, ELECTRONIC-STRUCTURE OF INSULATING SALTS OF THE KAPPA-(BEDT-TTF)(2)X FAMILY STUDIED BY LOW-TEMPERATURE SPECIFIC-HEAT MEASUREMENTS - COMMENT, Physical review. B, Condensed matter, 56(2), 1997, pp. 949-950
Recently reported specific-heat measurements by Nakazawa and Kanoda be
tween 20 and 50 K show no evidence for an expected antiferromagnetic o
rdering transition in the quasi-two-dimensional (2D) molecular conduct
or kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl [Y. Nakazawa and K. Kanoda, Phys.
Rev. B 53, R8875 (1996)]. Although the absence of an observable trans
ition was taken as evidence for 2D short-range ordering at elevated te
mperatures, even a small increase in pressure from the application of
the grease used to mount the sample would shift this magnetic transiti
on below 20 K. In their paper, Nakazawa and Kanoda erroneously assume
that pressure-induced effects can be ruled out by the magnetic-field i
ndependence of the low-temperature specific heat below 3 K. In this Co
mment, we explain why this assumption is invalid. We conclude that spe
cific-heat measurements in the intermediate temperature range of 3-20
K are needed before the absence of a discernible magnetic and/or press
ure-induced phase transitions can be asserted.