  We report on the detection of quasi-periodic micro-structure in three
millisecond pulsars (MSPs), PSRs J1022+1001, J2145-0750 and J1744-1134, using
high time resolution data acquired with the Large European Array for Pulsars at
a radio frequency of 1.4 GHz. The occurrence rate of quasi-periodic
micro-structure is consistent among pulses with different peak flux densities.
Using an auto-correlation analysis, we measure the periodicity and width of the
micro-structure in these three pulsars. The detected micro-structure from PSRs
J1022+1001 and J1744-1134 is often highly linearly polarised. In PSR
J1022+1001, the linear polarisation position angles of micro-structure pulses
are in general flat with a small degree of variation. Using these results, we
further examine the frequency and rotational period dependency of
micro-structure properties established in previous work, along with the angular
beaming and temporal modulation models that explains the appearance of
micro-structure. We also discuss a possible link of micro-structure to the
properties of some of the recently discovered fast radio bursts which exhibit a
very similar emission morphology.
