Is the string theory model of critical exponents relevant to materials such as Dy2Ti2O7 in relation to magnetic monopoles?

ABSTRACT Castelnovo et al. have proposed that magnetic monopoles emerge in spin ice. Motivated by the early studies of Fisher and Berker (FB), we here examine the possible relevance of a particular string model proposed in the literature for critical exponents in such materials. The value discussed by FB follows quite generally from the proposals in the considered model, independently of the parameter of string theory FB propose as a further critical exponent, and this determines the string theory parameter.