Muons and magnets

Abstract:

The quasi-one-dimensional molecule-based Heisenberg antiferromagnet Cu(NO3)2(pyz)3 has an intrachain coupling J = 13.7(1) K () and exhibits a state of long-range magnetic order below TN = 0.105(1) K. The ratio of interchain to intrachain coupling is estimated to be |J'/J| = 3.3 × 10-3, demonstrating a high degree of isolation for the Cu chains.

Abstract:

The experimental technique of a.c. susceptibility can be used as a probe of magnetic dynamics in a wide variety of systems. Its use is restricted to the low- frequency regime and thus is sensitive to relatively slow processes. Rather than measuring the dynamics of single spins, a.c. susceptibility can be used to probe the dynamics of collective objects, such as domain walls in ferromagnets or vortex matter in superconductors. In some frustrated systems, such as spin glasses, the complex interactions lead to substantial spectral weight of fluctuations in the low-frequency regime, and thus a.c. susceptibility can play a unique role. We review the theory underlying the technique and magnetic dynamics more generally and give applications of a.c. susceptibility to a wide variety of experimental situations.