Is a Griffiths phase a prerequisite for colossal magnetoresistance?
Detailed measurements of the magnetic and transport behavior of the two La(1-x)Ca(x)MnO(3) single crystals exhibiting colossal magnetoresistance are summarized. The x=0.21 sample exhibits unusual exponents (delta = 20+/-1, gamma = 1.71+/-0.1, beta = 0.09+/-0.01, T(C) = 182+/-1 K) and, more importantly, a Griffiths phase characterized by an exponent lambda = 0.70+/-0.2. By contrast, the x=0.20 specimen displays Heisenberg model behavior with no evidence of such a phase. Thus while a Griffiths phase accounts for the behavior of La(1-x)Ca(x)MnO(3) near optimal doping, it does not appear to be a prerequisite for colossal magnetoresistance in this system.
Jiang
Wanjun
W
Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2 Canada. jiang@physics.umanitoba.ca
Zhou
XueZhi
X
Williams
Gwyn
G
Mukovskii
Y
Y
Glazyrin
K
K