Description |
In this talk, I will show some experimental results concerning the effect
of dilute disorder on the ground state and excitations of quantum spin 1/2
chains. The disorder is induced by doping either magnetic or nonmagnetic
impurity in two representative Heisenberg spin 1/2 chain systems. The
specific results that I will show include: (i) finite-size effects arising
due to spin 0 or spin 1 impurities leading to gapping of the spin
excitations; and (ii) anisotropic spin 1/2 impurities leading to
Heisenberg to Ising crossover.
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