Summary: HighTemperature Series Analysis of 2D RandomBond Ising Ferromagnets Confirms
the Shalaev, Shankar and Ludwig Exponents
Alexandra Roder 1 , Joan Adler 2 and Wolfhard Janke 1
1 Institut f¨ur Physik, Johannes GutenbergUniversit¨at Mainz, Staudinger Weg 7, 55099 Mainz, Germany.
2 Department of Physics, Technion, Haifa 32000, Israel.
(February 23, 1998)
We analyse new hightemperature series expansions for the
susceptibility, Ø, of the twodimensional randombond Ising
ferromagnet with a symmetric bimodal distribution of two
positive couplings J1 and J2 . By studying a wide range of
coupling ratios J2=J1 we obtain compelling evidence for a
critical behavior of the form Ø ¸ t \Gamma7=4 j ln tj 7=8 , as predicted
theoretically by Shalaev, Shankar, and Ludwig.
The study of critical phenomena in real materials is
often complicated by the influence of impurities and in
homogeneities. Since this is the typical situation in most
experiments, it is of great importance to develop a theor
etical understanding of the role of these nonideal effects.
One important question is whether the critical properties
of the considered system are robust against such random