Low-temperature behavior of a magnetic impurity in a Heisenberg chain

Using the bosonization technique, we have studied a spin-1/2 magnetic impurity in Heisenberg chain, and shown that the impurity specific heat and spin susceptibility have an anomalous temperature dependence. The temperature dependence of the impurity specific heat is C-im(T) similar to T-mu, mu = 4 - 1/g(1 - g)(2), for g(c) < g < 1. The impurity spin susceptibility has the following temperature dependence: chi(im)(T) similar to T-nu, v = 3 - 1/g(1 - g)(2), for g(c) < g < 1, and nu = -1, for g less than or equal to g(c), where g(c) satisfies 4g(c) = (1 - g(c))(2), and g is a dimensionless coupling strength parameter.