Universality of boundary magnetizations in one-dimensional magnets

Hitoshi Asakawa, Masuo Suzuki

Michael Bortz, Jesko Sirker

The magnetic susceptibility of the one-dimensional Hubbard model with open boundary conditions at arbitrary filling is obtained from field theory at low temperatures and small magnetic fields, including leading and next-leading orders. Logarithmic contributions to the bulk part are identified as well as algebraic-logarithmic divergences in the boundary contribution. As a manifestation of spin-charge separation, the result for the boundary part at low energies turns out to be independent of filling and interaction strength and identical to the result for the Heisenberg model. For the bulk part at zero temperature, the scale in the logarithms is determined exactly from the Bethe ansatz. At finite temperature, the susceptibility profile as well as the Friedel oscillations in the magnetisation are obtained numerically from the density-matrix renormalisation group applied to transfer matrices. Agreement is found with an exact asymptotic expansion of the relevant correlation function.

Kazuyuki Matsumoto, Yasuhiro Akutsu, 和幸 松元 +1 more

(Received ) This paper investigates the generalized McCoy-Wu type random Ising model. It is found that boundary magnetization behaves as (TciT) fl 0 , fl 0 = 1:0 just below the ’critical temperature’. From numerical analyses it is revealed that this type of critical behavior, fl 0 = 1:0, would be universal for any type of randomness. This universal behavior is explained in terms of the destruction of the devil’s staircase structure. As an observable result of this model, the integrated distribution function of boundary magnetization is suggested.

Hirokazu Fujisaka, Toshijiro Tanaka

Steven P. Strong, Andrew J. Millis

We use mappings onto soluble models and Abelian bosonization to determine the phase diagram and correlation functions of a model of two coupled spin chains. We find quantum disordered singlet phases and magnetic phases and determine the phase boundaries, universality classes of transitions, and correlation functions. We believe our model captures the essential physics of the interplay between the Kondo effect and magnetic ordering, which may be important for the heavy fermion materials.

Nikolaos G. Fytas, Panagiotis E. Theodorakis