A Review of Non-resonant Microwave/RF Absorption in Cuprates and Iron Pnictides Superconductors

Immediately after the discovery of high Tc cuprates by Bednorz and Muller, a new phenomenon, now known as ‘non-resonant microwave/rf absorption’ (NRMA), was discovered by Bhat and co-workers. This phenomenon, NRMA, can probe several aspects of superconductivity in cuprates, namely fluxon dynamics, granularity and Meissner fraction, boundary currents and shielding, the manifestation of hysteretic and non-hysteretic Josephson junctions, ‘normal’ and ‘anomalous’ microwave absorption, etc. NRMA has recently been observed and reported in iron pnictide superconductors. Exciting NRMA features common to cuprates and iron pnictides are identified, reviewed, and discussed in the context of existing models in the literature. Further, a first observation and report of NRMA in the normal state of iron pnictide superconductor is reviewed in the context of possible magnetic contributions that require further experimental verification.